57135408 chemistry 5070 complete notes for o level (1)

Muhammad Hassan Nadeem

Experimental Chemistry Chemistry - 5070

Experimental ChemistryIn this topic, you will learn: Hazard warning labels. Appropriate apparatus for measurement of mass, volume, time

and temperature. The measuring units for mass, volume, time and temperature. Methods for collecting gasses. Identification of Gases.

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Hazard Warning LabelsTo help make the use and handling of chemicals safe, all chemicals have warning signs on their labels.You should be familiar with the following.

Hazard Warning LabelsLabel Description Label Description

Wear eye protection.You must wear safetygoggles.

Flammable liquids.Liquids which igniteon contact withignition sources.

Harmful substances.Handle with care andavoid contact with skin.

Flammable gases.Gases which arecompressedliquefied ordissolved underpressure. Catch firevery easily.

Toxic substances.Very poisonous so do notsmell it or touch it withyour fingers.

Oxidizingsubstances.Help fire to burnvery fiercely.

Corrosive substances.Keep off the skin,otherwise it will itch andburn.

Explosivesubstances.Substances whichreact very violentlyand explode.

Flammable solids.Gases which arecombustible or emit aflammable gas when wet.Catch fire very easily.

Radioactivesubstances.Substance whichgive off harm fullradiations: alpha,beta or gamma rays.



Measurement: Mass, Volume, Time andTemperatureMass

Mass of a substance is the amount of matter it contains. Mass is measured in kilograms (kg) and grams (g).

Conversion of Mass 1000 mg = 1g1000 g = 1 kg1000 kg = 1 tone

There are two main devices to measure mass of a substance:Beam balanceElectronic balance

Name Picture DescriptionBeam balance In a beam balance, a weight

is moved along horizontalscale until is balances themass of object on the scalepan.

Electronic balance Electronic balance is easy touse and can measure toaccuracy of 0.001 g veryquickly.

Volume Volume of a substance is the amount of space it occupies. Unit for measuring volume is cubic centimeters (cm3), cubic decimeters (dm3), cubic meters (m3)

and liter.

Conversion of volumes 1000 cm3 = 1 dm3

1 dm3 = 1 liter1000 dm3 = 1 m3



Following apparatus are used for measuring volumesName Picture Description

Beaker Measures approximate volume

Burette Is accurate to the nearest 0.1cm3. The volume of liquidrequired is run off from thebottom through tap.

Volumetric flask Measures fixed volumes of 100cm3, 250 cm3, 1 dm3

Measuring cylinder Is accurate to nearest cm3.Read off the volume with theeye level at the bottom of themeniscus.

Pipette Measures fixed volumes of 25cm3, 50 cm3, 10 cm3 veryaccurately.

Gas syringe Measures volume of gas and ismade of glass.

Plastic Syringe Measures small volumes ofliquid.



Time Time is the interval between two occurrences. Time is measured using stopwatch. Measuring unit for time is second (s). Most stopwatch measure to accuracy of 0.01 s.

Conversion of Time 60 s = 1 min60 min = 1 h24 h = 1 day

Temperature Degree of hotness and coldness is called temperature. The temperature of a liquid or gas can me measured using a thermometer. Measuring unit for temperature is oC.

Collection of Gases The collection of a gas depends on whether the gas is heavier or lighter than air, and also if the

gas is soluble or insoluble in water. Heavy gas can be collected by downward delivery. Light gas can be collected by upward delivery. Insoluble gas can be collected by trapping the gas above water.

Properties of some gases useful to decide the method of collection.Gas Color Density

(compared to air)Solubility(in water)

Ammonia Colorless Lighter Extremely solubleCarbon dioxide Colorless Heavier Slightly solubleChlorine Green/yellow Much heavier SolubleHydrogen Colorless Much lighter InsolubleHydrogen chloride Colorless Slightly heavier Very solubleOxygen Colorless About the same Slightly soluble



Name Picture DescriptionUpward delivery Used for gases which

are less dense than airfor example ammonia,hydrogen.

Downward delivery Used for gases whichare denser than air forexample carbondioxide, chlorine andhydrogen chloride gas.

Identification of GasesTests for gases

Gas Color and smell TestChlorine Pale green, choking smell Bleaches damp litmus paper and turns it redHydrogen Colorless, odorless ‘Pops’ with a glowing splinterOxygen Colorless, odorless Relights a glowing splinterCarbon dioxide Colorless, odorless Turns lime water milkyAmmonia Colorless, pungent smell Turns damp litmus paper blueSulphur dioxide Colorless, choking smell Turns acidified potassium dichromate(VI) from yellow to green




The Particulate Nature of Matter Chemistry - 5070

The Particulate Nature ofMatterIn this topic, you will learn: Different states of matter Movement of particles in solids, liquids and gases Effects of diffusion in terms of particles Kinetic particle theory Interconversion between three states of matter



States of Matter Matter is defined as anything that has mass and takes up space. Every substance exists in three different forms solid, liquid and gas. All three states of matter expands (increase in volume) when temperature is increased. All three states of matter contracts (decrease in volume) when temperature is decreased.

Properties of MatterProperty Solids Liquids Gases

Shape Solids have definiteshape

Liquids take the shape oftheir container

Gases take shape oftheir container

Volume Solids have a fixedvolume

Liquids have fixedvolume

Gases take on thevolume of theircontainer

Compressibility Solids are notcompressible

Liquids are difficult tocompress

Gases are easilycompressible

Density Solids have high density Liquids have a mediumdensity

Gases have a very lowdensity

Ease of flow Solids do not flow Liquids flow Gases flow

Kinetic Theory This is a theory about the way particles move about in solids, liquids and gases.

Property Solid Liquid GasPacking betweenparticles

Very close together Further apart Furthest apart

Arrangement ofparticles

Arranged in regularrows

Not regularly arranged Randomly arranged

Forces ofattraction betweenparticles

Held together verytightly

Not tightly held Free to move

Motion of Particles Vibration about fixedposition

Changing places Moving in all directions



Speed of motion Not moving from theirmean position

Moving about Moving very fast

Diagrammaticrepresentation ofthe particles ineach of thephysical states When a solid is heated the particles gain energy and vibrate more strongly, eventually the

particles have enough energy to break the forces holding the particles together and change intoliquid.

If more heat is supplied, particles in liquid move much more faster, when boiling point isreached the particles have enough energy to break the forces attracting them together and thuschange into a gas.

Changes of State The constant temperature at which a pure solid changes into a liquid is called its melting point. The constant temperature at which a pure liquid changes into a gas is called its boiling point. Melting is the change from solid to liquid. Evaporation is the change from liquid to gas at room temperature. Boiling is the change from liquid to gas at specific temperature. Sublimation is the direct change from solid to gas for example carbon dioxide i.e. dry ice and

iodine are sublimes. Solidification or Freezing is the change from liquid to solid. Condensation is the change from gas to liquid.

The melting and boiling points of some common chemical substancesSubstance State Melting point/oC Boiling point/oCOxygen Gas -219 -183Nitrogen Gas -210 -196Ethanol (alcohol) Liquid -117 78Water Liquid 0 100Sulphate Solid 115 444Common salt Solid 801 1465Copper Solid 1083 2600Carbon dioxide gas -78 -78



Heating Curve The graph shows the changes in state when a particular solid is heated:

At A, particles are closely packed in a purely solid state with only the ability to vibrate aboutfixed position.

At B, the particles have gained sufficient energy to move further apart, and it starts changinginto liquid. Two states, solid and liquid exist here.

At C, the particles are at purely liquid state gaining more heat energy and raising itstemperature.

At D, particles have gained sufficient energy to move randomly and separate very far apart. Theliquid starts changing into gas. Two states liquid and gas exist here.

At E, the particles are in purely gaseous state gaining more heat and rising in temperature.Diffusion Diffusion is natural mixing of

particle. If you drop a drop of ink in a glass

of water, you will notice after sometime the color of the ink will bespread evenly in water. This is dueto diffusion.

It is diffusion through which a smelltravels through kitchen and reachesyour nose in some other room.

Diffusion takes place much morequickly with gases, than with liquidsor solids.



The rate of diffusion depends upon the molecular mass of the particles (slower, if heavier) andtemperature (faster, if warmer).




Methods of Purification Chemistry - 5070

Methods of PurificationIn this topic, you will learn: Difference between pure substances and mixtures Types of mixtures Effects of impurities on melting and boiling points Method of purification Methods of testing purity of substance



Pure substances and mixtures A pure substance contains only one type of substance or atom for example water. A mixture is made of more than one substance or atom for example air is mixture of oxygen,

nitrogen, carbon dioxide and other gases. Impurity lowers the melting point and raises the boiling point of any substance.

Types of mixtures Homogeneous mixture is when substances completely mix to form one phase for example salt

dissolved in water forms one phase and is thus homogeneous. Heterogeneous mixture is when substances do not mix and form more than one phase for

example sand mixed in water forms two phases and is thus heterogeneous.

Important examples of different types of mixtureType ofmixture

Mixture Description Examples

Homogeneousmixtures(solutions)

Solutions of solid in liquid Transparent solution ofsolid dissolved in liquid

Sea water, sugar inwater, salt solution

Solutions of two miscible liquids Single layer oftransparent liquid

Vodka (alcohol andwater)

Solutions of gas in liquid Transparent solution ofgas dissolved in liquid

Mineral and sodawaters, champagne

Mixture of gas in gas Transparent mixture oftwo or more gases

Air

Alloy of two solid metals Solid, evenly spreadmixture of two metals

Brass, Bronze

Heterogeneousmixtures

Suspension of solid in liquid Cloudy mixture of solidparticles suspended in aliquid

River water carryingmud and silt, flour inwater.

Gel Jelly-like mixture ofsolid and liquid, liquidtrapped in solid

Fruit jelly, agar gel

Emulsion of two immiscibleliquids

Cloudy mixture of tinydrops of one liquidsuspended in anotherliquid

Skin cream, milk, saladdressing, mayonnaise

Aerosol of either a liquid or solidin gas

Small droplets of liquid,or particles of solid,dispersed in a gas

Liquid in gas: mist,cloudsSolid in gas: smokedusty air

Foam of gas in liquid Many small bubbles ofgas trapped in liquid

Washing lather, shavingform

Solid foam of gas in solid Many small bubbles ofgas trapped in a solid

Polystyrene foam, foamrubber, bread



Methods of PurificationDissolving, Filtering and Evaporating

It is suitable for separating two solids, given that one solid is soluble and other is insoluble, incertain solvent. For example mixture of salt and sand.

Dissolve the mixture in water. Only salt will be dissolved. Filter the solution, sand will be collected in filter paper as residue. And salt solution will pass the

filter paper and collected as filtrate. Salt solution is heated; water evaporates leaving behind the crystals of salt.

Decanting and Centrifuging Decanting means carefully pouring the

liquid in another container and leavingbehind the undissolved solid. This methodis suitable for separating suspension(undissolved solid) for example sand fromwater.

In centrifuging test tube is revolved withhelp of an electric motor, which causesundissolved solid to settle down. The wateris then poured in container by hand leavingbehind solid in test tube. Decanting Centrifuging



Separating Funnel This technique is suitable for two liquids which do not

mix together i.e. immiscible liquid (for example oil andwater).

The more dense liquid settles at the bottom while theless dense liquid floats over the surface.

The more dense liquid is tapped off wile less denseliquid remains in the funnel

Sublimation This technique can be used to two substances, provided that one

substance sublimes and other does not. The mixture is placed in an evaporating dish with a glass funnel inverted

on it. Evaporating dish is heated. The substance which sublimes will stick with the walls of funnel. And

other substance will remain in the dish.

Simple Distillation Used to separate pure liquids

from a solution. Distillation flask is heated and

when the solution boils steam isgiven off.

Steam travels up the flask and iscondensed in condenser, fromwhere the liquid flows in theconical flask as distillate.

After the process only impuritiesand left behind in the distillationflask. Pure liquid is collectedfrom the conical flask.



Fractional Distillation This method is used to separate liquids

with different boiling points. It is same like simple distillation whereas

in it fractionating column is used toseparate two liquids.

Fractionating column is packed with glassbeads to provide larger surface area forquick condensation.

When boiling point of any liquid isreached, it’s vapor rises, passes throughfractionating column, condensed in Liebigcontainer and collected in conical flask.

If any liquid with high boiling pointevaporates it is condensed by fractionatingcolumn.

Paper Chromatography Chromatography is used to separate

colours, pigments and dyes. It can tell whether a solution has become

contaminated. A drop of concentrated solution is usually

placed on a pencil line near the bottomedge of a strip of chromatography paper.

The paper is then dipped in the solvent. The solvent begins to move up the paper

by capillary action. Solvent moves up the paper taking

different components along at differentrates.

The separation of mixture is complete. The distance moved by a particular spot is measured and related to the position of the solvent

front. =In the following case Rf value would be:



= Locating agents are used to separate substances which are colorless.Purity of a Substance

Effect of Impurity on a Substance Impurities lower the melting point (or freezing) point of a substance. Impurities raise the boiling point of a substance. All impure substance melts or boils at a range of temperatures.

Testing the Purity of a substance A pure substance has a fixed and exact melting (or freezing) point. A pure substance has a fixed and exact boiling (or condensation) point. A pure substance shows only one spot on a chromatogram.



The Structure of the Atom Chemistry - 5070

The Structure of the AtomIn this topic, you will learn: The relative charges of proton, electron and neutron. Structure of an atom consisting of proton, electron and neutron Proton number and Nucleon number. Isotopes. Relative atomic mass of an element. Introduction to Periodic Table.




Particles Present in an Atom All element are made of atoms.. Atoms are made up of sub-atomic particles called protons, neutrons and electrons. Proton number of any atom is always equal to its number of electrons. That’s why the overall

charge of any atom is 0 i.e. neutral.

Particle Symbol Relative Mass Relative chargeProton p 1 +1

Neutron n 1 0Electron e 11840 -1

Proton Number and Nucleon Number The proton number of an element is the number of protons in its atom. The nucleon number of an element is the total number of protons and neutrons in its atom. Nucleon number is considered the relative atomic mass of any atom. Consider Sodium atom in the below picture

We are given Nucleon and Proton number. We can deduce that:Number of Protons = 11Number of Electrons = 11 (same as proton)Number of Neutrons = Nucleon Number – Proton Number = 23 – 11 = 12

Isotopes Isotopes are atoms of the same element with different number of neutrons. Isotopes of different elements have different masses. Different isotopes have same chemical properties but different physical properties.

Different Isotopes of HydrogenIsotope Name Symbol Number of

neutronsNumber ofprotons

Number ofelectrons

Isotopicabundance

Hydrogen 0 1 1 99.985 %Deuterium 1 1 1 0.015 %Tritium 2 1 1 artificial

Proton Number (Z)

Nucleon Number (A)

SYMBOL




The Structure and Arrangement of Particles in an Atom The protons and neutrons are held, tightly packed together, the center of the atom which is

called the nucleus. The size of nucleus is very small compared to the overall size of atom. Electrons move around the nucleus (like planets orbit around sun).

The path of electrons can be referred as shell. The shells are numbered from nucleus outward. The formula to calculate the maximum number of electrons in a shell is 2n2 where n is the

number of shell.The first shell can hold up to two electrons. 2x(4)2 = 2The second shell can hold up to eight electrons. 2x(2)2 =8The third shell can hold up to eighteen electrons. 2x(3)2 =18

Electrons in the outer most shell of any atom is called valence electron. Electronic configuration of any atom is the number of electron present in each cell for example

electronic configuration of Sodium (Na) is 2,8,1.




Introduction to the Periodic Table. In Periodic table elements are arranged in order of their increasing proton number. Vertical columns are called groups. Horizontal rows are called periods. Group number indicates the no of valence electrons. Period number indicates the no of electron shells. On left side of periodic table are metals, which are elements of 1 – 3 valence electrons. On right side of periodic table are non-metals, which are elements of 4 – 7 valence electrons On the extreme right-hand side are inert gases, which have 2 or 8 valence electrons.




Elements, Compounds and Mixtures Chemistry - 5070

Elements, Compounds andMixturesIn this topic, you will learn: Atom and Molecule Difference between elements, compounds and mixtures



Elements and Atoms An element is a substance which can not be split into two or more simpler substances by

chemical means. An atom is the smallest possible particle of an element that can take part in chemical reaction. Elements are made up of atoms. There are 92 naturally occurring elements.

MATTER

PURESUBSTANCES

ELEMENTS COMPOUNDS

MIXTURES

HEMOGENEOUS HETROGENEOUS

46.60%

27.80%

5.00%

3.40% 9.00%

8.10%

Composition of the earth's crust

Oxygen

Silicon

Iron

Calcium

Other

Aluminium



Molecules and Compounds A molecule is the smallest particle of a compound and is made up of group of same atoms. A compound is a pure substance which contains only one type of molecules made up of

different atoms chemically combined together.

Molecules of elements Molecules of compound

Mixtures and Compounds A mixture is not a pure substance as it contains a mixture of atoms and/or molecules which are

not chemically combined.For example Air is mixture of gases; Sea water is mixture of dissolved solids and water; Alloysare mixtures of metals.

A compound is a pure substance which contains only one type of molecules made up of atomschemically combined together.For example if iron (Fe) and Sulphur (S) are heated iron (II) sulphide is formed.+ →

No. Mixture Compound1 Component substances can be separated by

chemical means.Constituent elements cannot be separated bychemical means.

2 Its physical properties (color, density, etc.)are an average of those of the substances init.

Its physical properties are individual and not theresult of its elements.

3 Normally little or no energy is given out ortaken in.

Energy is usually given out or taken in when acompound is formed.

4 A mixture’s composition can vary. A compound’s composition cannot vary.5 Its chemical properties are result of the

substances in the mixture.Its chemical properties are quite different fromthose of its elements.

Cl

Methane gasCH4

H

HH

H

OH H

WaterH2O

N

H

HH

Ammonia gasNH3

Cl Cl

Chlorine gasCl2

N N

Nitrogen gasN2

H H

Hydrogen gasH2

O O

Oxygen gasO2




Bonding and Structure Chemistry - 5070

Bonding and StructureIn this topic, you will learn: Ionic Bonding Covalent Bonding Metallic Bonding Macromolecules Properties of Ionic Bonding Properties of Covalent Bonding Properties of Metallic Bonding



Bonding Bonding is the way in which atoms join together and combine with one another. The arrangement of resulting particle is called structure. It is only the valency electrons in the outermost shell which become involved in bonding. It is aim of every atom to achieve a noble gas structure (i.e. 8 electrons in outermost shell). It

makes it stable. Noble gas do not take part in chemical reactions as they have 8 electrons in their outermost

shells.

Structure of noble Gases

Metallic Bonding This type of bonding is only possible in metals. Metals have free electrons in their outermost shell. When they pack together they loose their electrons into the sea

of electrons. These electrons are free to move. It is because ofthese electrons that metals conduct electricity.

Properties of metals Reasons for these propertiesThey have high densities. Due to close packing of atoms on metals.They have high melting and boiling points. Strong forces of attraction between atoms cause high

melting point of metals.They are malleable and ductile. When force is applied to a metal, the atoms can slip over

one another. This allows the metal to be malleable andductile.

They are good thermal conductors. Vibration of atoms and outermost electrons helpstransfer of heat energy.

They are good electrical conductors. Free outermost electron cause metal to conductelectricity. When a metal is connected into a circuit theelectrons move towards the positive terminal, andelectrons form the negative terminal flow to the metalsto replace them.



Ionic bonding Ionic bonding only occur between a metal and a non-metal. Ionic bonds are formed when metallic atoms give away valence electrons to non-metallic atoms. By giving electrons metal becomes positively charged and on other hand by gaining electron non

metal becomes negatively charged. These oppositely charged attracts each other through strong electrostatic force of attraction,

forming the ionic bond.

Loosing electron Gaining Electron

Diagram for Reaction of Sodium with Chlorine to Form Sodium Chloride

Properties of typical ionic compounds Reasons for these propertiesThey are crystalline solids at room temperature. There is regular arrangement of the ions in a lattice.

Ions with opposite charge are next to each other.They have high melting and boiling points. Ions are attracted by strong electrostatic forces

which are not easy to break.They are often soluble in water. Water is a polar solvent. Charged ions can move

about in it.They conduct electricity when molten ordissolved in water.

In liquid form or solution, the ions are free to move.

They do not conduct electricity when solid. The charged ions are bonded together.



Covalent bonding Covalent bonding occurs between non-metals. Electrons are not transferred but shared in order to attain stability in the atoms that are used in

bonding. If one electron is shared between each atom then single covalent bond is formed. If two electrons are shared between each atom then double covalent bond is formed. If three electrons are shared between each atom then triple covalent bond is formed.

Hydrogen

Chlorine

Oxygen

Water



Ammonia

Methane

Properties of simple covalent compounds Reasons for these propertiesThey are often liquids or gases at roomtemperature.

These substances are made of simple molecules. Theyare joined by covalent bonds.

They have low melting and boiling points. Inter-molecular forces of attraction between are veryweak.

They are soluble in organic solvents such asethanol or methylbenzene.

Covalent molecular substances dissolve in non-polar(covalent) solvents.

They do not conduct electricity at all. There are no ions present to carry the charge.




Chemical Formulae and Equations Chemistry - 5070

Chemical Formulae andEquationsIn this topic, you will learn: Chemical Symbols Chemical Formulae Valency Relative Molecular Mass (Mr) The Percentage composition of Elements in a Molecule Empirical Formula Chemical Equations Ionic Equations



Chemical Reaction Chemical reaction is when two or more elements, compounds or molecules react together to

form something new. Reactants are what start a chemical reaction. Products are what are formed at the end of chemical reaction.

Types of reaction In decomposition reaction a compound breaks down to form two or more substances. In synthesis reaction a substance is formed by the combination of two or more substances. In neutralization reaction acid reacts with a base to form salt and water. In displacement reaction ion of less reactive element is displaced by the ion of more reactive

element (of same type). Precipitation reaction involves the formation of insoluble product. Combustion reaction of a substance involves its reaction with oxygen. Redox reaction involves oxidation and reduction of substances (discussed latter).Chemical Symbols Each element is represented by its own symbol. Symbol may me of one or two letters. The first letter is capital is second letter is a small letter.

Name of some elements Symbol Name of some elements SymbolAluminum Al Copper CuBarium Ba Mercury HgBoron B Silver AgLead Pb Gold AuZinc Zn Helium HeOxygen O Neon NeHydrogen H Potassium KNitrogen N Tin SnIodine I Sodium NaIron Fe Chlorine ClChemical Formulae



Chemical formula is the way of expressing ratio of combining numbers of atoms or ions. Valency is the combining power of an atom or ion. The valency of first element becomes the base of second element and the valency of second

element becomes the base of first element.X Y → X Y The bases are then further simplified if required.X Y → X Y → XY

Some common ionsValency Positively charger ions Negatively charged ions

1 SodiumPotassiumSilverCopper(I)HydrogenAmmonium

ChlorideBromideIodideHydroxideNitrateHydrogen carbonateHydrogen sulphate

2 Lead(II)Copper(II)MagnesiumCalciumZincBariumIron(II)Mercury (II)

BaSulphateSulphtiteCarbonateOxideSulphide

3 Iron(III)Aluminum

PhosphateRelative Molecular Mass Relative molecular mass (Mr) of a substance is the sum of relative atomic mass (Ar) of every

element in that substance.

Example: Relative Molecular Mass of Sulphuric Acid ( )Relative molecular mass of = (2 x 1) + 32 + (4 x 16)



The Percentage Composition of Elementsin a Compound.1. Write down the chemical formula of the substance.2. Find out its relative molecular mass.3. Divide the atomic mass of the element you want to calculate the percentage composition of,

with the relative molecular mass, and multiply the result with 100%.

Example: Percentage Composition of Sulphuric Acid ( )Relative molecular mass of = (2 x 1) + 32 + (4 x 16)

=98Ar of Hydrogen = 2 % of Hydrogen = × 100 = 2.04%Ar of Sulphur = 32 % of Sulphur = × 100 = 32.64%Ar of Oxygen = 64 % of Oxygen = × 100 = 65.31%Mass of an Element in a Compound

If we know the percentage of an element in a compound, then mass of that compound can alsobe found by following equation:= % ×= ×

ExampleCalculate the mass of sodium in 10 g of sodium carbonate crystals( . 10 ).

Ar of atoms of sodium in . 10 = 2 x 32 = 46

Mr of the compound . 10 = 286

Mass of sodium in 10 g of sodium carbonate crystals = × 10 = 1.61Empirical Formulawww.revision-notes.co.cc


The empirical formula of a compound is the simplest formula which shows the relative numbersof the atoms of the different elements present.

Empirical formula can be determined once the percentage or mass of each element in acompound is known.

To the rules for finding empirical formula are:1. Divide the percentage or mass of each element by its relative atomic mass.2. Divide by the smallest number to convert to the simplest ratio.3. The number of atoms of the different elements is the empirical formula.

ExampleGiven that a molecule contains 88.89% oxygen and 11.11% hydrogen , what is its empirical formula?

H O1 Dividing % by Ar 11.111 = 11.11 88.8916 = 5.552 Simplest ratio 11.115.55 = 2 5.555.55 = 13 Empirical formula

Chemical equation A chemical equation is a useful way to summarizes what has happened in a chemical reaction. Reactants are written on the left side of equation while products are written after the reactants

preceded by an arrow with its head facing right.

1. Write down equation in words reactants on the left side, an arrow pointing towards right sidefollowed by the products. + →

2. Then write down the correct chemical formula.+ →3. Balance the equation number of moles before chemical formulas of both products and reactants

where necessary. This involves making sure that the number of atoms of each element beforeand after the reaction is the same. 2 + → 2

4. Finally add the state symbols in the equation for every reactant and product, after its chemicalformula. Solid is (s), liquid (l), gas is (g) and aqueous is (aq). Aqueous means dissolved in water.2 ( ) + ( ) → 2 ( )Ionic Equation



If the reaction is involving reactants in aqueous state then ionic equation is written to showwhich particles are actually taking part in chemical reaction.

The ions which do not take part in chemical reaction are called spectator ions.1. Write the real chemical equation first.( ) + ( ) → ( ) + ( )2. The chemicals which are in aqueous state before and after the reaction are split into their

respective ions. [ ( )] + [ ( )] → [ ( )] + ( )3. The ions which do not take part in chemical reaction (i.e. The ions which are same before and

after chemical reaction) are cut.[ ( )] + [ ( )] → [ ( )] + ( )4. This leaves us with the essential ionic equation.( ) + ( ) → ( )

Naming chemical Compounds If there is a metal it is named first. Compound containing two element have their name ending with ...ide; for example sodium

chloride (NaCl) and calcium bromide (CaBr2). Compound containing oxygen end their names with ...ate; for example calcium carbonate

(CaCO3) and potassium nitrate (KNO3). In the names of some compounds prefixes are used to describe the number of particular atom

in the compound; for example carbon monoxide (CO), carbon dioxide (CO2), sulphur trioxide(SO3) and dinitrogen tetraoxide (N2O4).




The Mole Chemistry - 5070

The MoleIn this topic, you will learn: What is Mole? Moles of Atoms Moles of Molecules Moles of Gases Calculating Percentage Purity and Yield



What is a Mole? Amole is defined as the amount of substance which contains the Avogadro Number of particles. The Avogadro Number (or Avogadro Constant) is defined as the number of atoms in 12 g of the

carbon-12 isotope. The value of Avogadro Number is 6.02 x 1023. The mass of one mole of atoms is its relative atomic mass in grams. For example 23 g of sodium

will be one mole of sodium and thus will contain Avogadro Number of sodium atoms. The mass of one mole of molecules is its relative molecular mass in grams. For example 18 g of

water (H2O) will be one mole and thus will contain Avogadro Number of water molecules. One mole of any gas at room temperature and pressure will occupies a fixed volume of 24000

cm3 (24 dm3). Equal volumes of all gases at the same temperature and pressure contain the same number of

particles.

Example 1 mole of H2 molecules has mass of 1 x 2 = 32 g 1 mole of O2 molecules has a mass of 16 x 2 = 32 g 1 mole of CuSO4.5H2O has mass of 64 + 32 + (16 x 4) + [(1 x 2) + 16] x 5 = 250 g

Volume of one mole of O2 at r.t.p is 24000 cm3. Volume of one mole of Cl2 at r.t.p is 24000 cm3. Volume of one mole of Br2 at r.t.p is 24000 cm3.

24 grams of magnesium would contain 6.02 x 1023 magnesium atoms. 56 grams of iron would contain 6.02 x 1023 iron atoms. 18 grams of water would contain 6.02 x 1023 water molecules.

Calculations with Moles = = × = × = ×




Electrochemistry Chemistry - 5070

ElectrochemistryIn this topic, you will learn: Some electrical devices and circuit symbols Conductors and Non-conductors Electrolytes, Weak-electrolytes and Non-electrolytes Electrolysis Factors effecting electrolysis Industrial applications of electrolysis Dr y cells



Electrical Devices and Circuit Symbols Cell is source of electricity. Battery is a collection of cells. Switch is used to stop the flow of current. Bulb is used to register whether current is flowing. Voltmeter is used to measure current. Ammeter is used to measure current. Resistor ensures that a suitable amount of current is flowing. Variable resistor is resistor those rating can be changed. Electrodes are plates which carry electricity into the liquid. Cathode is the electrode connected to the negative terminal of the battery. Anode is the electrode connected to the positive terminal of the battery. Cation are positively charged ion that travels to the cathode during the electrolysis. Anion are negatively charged ion that travels to the anode during the electrolysis.

Electrical Device Circuit SymbolCell

Battery

Bulb

Switch

Ammeter

Voltmeter

Resistor

Variable resistor (rheostat)



Conductors and Non-Conductors

Conductors A conductor is a substance which conducts electricity but is not chemically changed during the

conduction. Conductors have free moving valence electrons which conducts electricity. All metals and graphite are conductors

Non-conductors A non-conductor is a substance which does not allow the passage of electricity. Non-conductors do not have free valance electrons and thus do not conduct electricity. All non-metals except graphite are non-conductors.

Electrolytes, Weak-electrolyte and Non-electrolyte

Electrolytes Electrolytes are compounds which when molten or dissolved in water conduct electricity. All acids, alkalis and salts are electrolytes. They conduct electricity by the movement of ions between electrodes.

Weak-electrolyte Weak acids and weak alkalis are classified as weak-electrolytes. They contain only few ions.

Non-Electrolyte Non-electrolyte is a liquid which does not allow the passage of electricity. Distilled water, alcohol, turpentine, oil, paraffin and other organic solvents are examples of non-

electrolytes.

Strong electrolytes Weak electrolytes Non-electrolytesAqueous sulphuric acid Limewater EthanolAqueous nitric acid Ammonia solution Tetra chloromethaneAqueous hydrochloric acid Aqueous ethanoic acid Tri chloromethaneAqueous potassium hydroxide Aqueous sulphurous acid Pure waterAqueous sodium hydroxide Aqueous carbonic acid Sugar solutionCopper(II) sulphate solution Molten sulphur

Electrolysis The process of decomposing a compound by passage of an electric current is called electrolysis.



When electricity is passed through electrolyte, anions start moving towards anode and cationstowards cathode.

Anions are usually non-metal ion for example Cl-, Br- and O2-. Cations are usually metal ion for example Ag+, Cu+2 and Pb+2. When anion reach anode they lose their electron to anode, which is ready to gain electron due

to positive charge. When cation reach cathode they gain electron from cathode, which is ready to donate electron

due to negative charge.

Factors Affecting Electrolysis

Position of ion in reactivity series More reactive ion undergoes discharge.

Cations AnionsK+

Na+

Ca2+

Mg2+

Zn2+

Fe2+

Pb2+

H+

Cu2+

Ag+

SO42-

NO3-

Cl-

Br-

I-

OH-

Concentration If the concentration of particular ion is high, then this can alter the preferential discharge. Concentrated ion will be discharged.

Type of electrode Type of electrode used can affect the electrolysis. Carbon electrodes are inert electrodes and do not effect electrolysis.

Difficulty ofdischargedecreases



Electrolysis of concentrated Sodium Chloride solution

Ions present in the solution Anions present in solution are OH- (from water) and

Cl- (from salt). Cations present in solution are H+ (from water) and

Na+ (from salt).

Reaction

Anode Chloride and hydroxide ions migrate towards anode. Chloride ions are discharged as the concentration of

chloride ion is higher. 2 chloride ions lose 2 electrons to form chlorine gas.2 → 2 +

Cathode Sodium and hydrogen ion travel towards cathode. Hydrogen ion is discharged as sodium is too high up

in the reactivity series. 2 hydrogen ions gains 2 electrons to form hydrogen

gas. 2 + 2 →

Electrolysis of dilute sulphuric acid

Ions present in the solution Anions present in solution are OH- (from water) and SO4

-2 (from acid). Cation present in solution is H+ from both water and acid.

Reaction

Anode Hydroxide and sulphate ion migrate towards anode. Hydroxide ion is preferentially discharged as it is at the bottom of the reactivity series. Hydroxide ion loses 1 electron to form oxygengas which bubbles out and water which stays in

the solution. 4 → 2 + + 4Cathode

Hydrogen ion is discharged as it is only cation present.



2 hydrogen ions gains 2 electrons to form hydrogen gas.2 + 2 →Industrial Applications of Electrolysis

Purification of metals Impure copper is made anode. Pure copper is made cathode. Electrolyte is acidified copper (II) sulphate. When electricity flows copper dissolves from impure anode and goes into solution as copper

ions. Impurities do not dissolve, and instead fall off the anode as anode sludge. At cathode, the copper ions are deposited as pure copper metal.

At anode → + 2

At cathode + 2 →

Electroplating Electroplating is a process of forming thin protective coating of a

metal on the surface of another which is likely to corrode. Object to be plated is made cathode. (Spoon) Anode is made of the metal we wish to plate with. (Silver Ag) Electrolyte is the solution of salt of the metal. (Silver Nitrate

AgNO3) Anode: → + 2 (Silver dissolves from anode) Cathode: + 2 → (Silver deposits on the object)

Some commonly Electroplated ObjectsMetal Object

Zinc Dustbins, bucketsChromium Car bumpers, bicycle handle

barsSilver Watches, braceletsCopper SaucepansNickel CutleryGold Jewellery, watches



Electrical Cell A simple cell is a device that converts chemical energy into electrical energy. Each simple cell

consists of:2 electrodes of 2 different metalsAn electrolyte solution containing an acid or an aqueous salt

As more reactive metal tends to undergo oxidation more easily, and naturally becomes thenegative terminal by losing electrons, which then travel via the external circuit to other metalelectrode.

The less reactive metal becomes the positive terminal, as it has a weaker tendency to loseelectrons.

The voltage of the cell depends on the position of the metal in the reactivity series. The far twometals are in the reactivity series more is the voltage.

ReactivityMagnesiumAluminumZincIronTinLeadCopperSilver

Reactivitydecreases



Dry cell In dry cell electrolyte is a paste. Carbon electrode is positive terminal. Zinc electrode is negative terminal. Ammonium chloride is used as electrolyte.




Chemical Reactions Chemistry - 5070

Chemical ReactionsIn this topic, you will learn: Exothermic reactions Endothermic reactions Energy changes involved in bond making Energy changes involved in bond breaking Factors affecting the speed of reactions Catalysts and Enzymes



Exothermic Reactions Exothermic reaction is one where energy (heat) is given out causing a temperature rise in the

surrounding. Making chemical bonds involves release of energy and is thus exothermic. Overall energy change is negative(∆ = − ). Activation energy needed is low. Combustion, Respiration and Neutralization reactions are exothermic reactions.

Endothermic Reaction Endothermic reaction is one where energy (heat) is taken in causing a temperature drop in the

surroundings. Breaking chemical bonds takes in energy from the surroundings and thus is endothermic. Overall energy change is positive(∆ = + ). Activation energy needed is high. Thermal decomposition (breaking of large molecule on heating) and dissolving are endothermic

reactions.



Rate of ReactionsMeasuring the rate of reactions

Direct Method: measuring the rate of change of mass at different intervals.

Indirect Method: measuring the external product given off for example gas evolved.



Factors affecting the rate of reactions The surface area of any solid reactants.

The greater the surface area the faster the rate of reaction. This means that powdered reactantswill react more quickly than reactants in ump form.

The concentration of the reactants.The rate of reaction increases when the concentration of a reactant in solution is increased. Thisis because at higher concentration, there is a greater likelihood that reacting molecules willcollide with one another with sufficient energy to form particles.

The temperature at which the reaction is carried out.The rate of reaction increases when the temperature of the reaction mixture is increased(because increase in temperature increases the kinetic energy of molecules thus increasing thenumber of effective collusions). Rate of reaction doubles with every 10oC increase intemperature.

The use of a catalyst.Catalyst increases the rate of reaction by lowering the activation energy needed. Catalyst doesnot change at the end of the reaction this means that a catalyst can be used over and overagain.

The pressure in case of gaseous reactions.In gaseous reaction speed of reaction increases if pressure is increased, this is because at lowerpressure gasses collide more frequently.

The light in some reactions.Some reaction take place faster when they absorb light for example formation of silver fromsilver salts takes place when a photographic film is exposed to light. In sunlight, green plants areable to carry on the process of photosynthesis.Redox Reactions

Redox reactions are one where oxidation and reduction occur simultaneously.

Oxidation and Reduction

Oxidation Gain in oxygen. Loss of hydrogen. Loss of electrons. Increase in oxidation number.

Reduction Loss of oxygen. Gain in hydrogen.



Gain in electrons. Decrease in oxidation number.

Oxidizing Agents and Reducing Agents Substances which helps oxidation to take place are called oxidizing agents (oxidants). Substances which help reduction to take place are called reducing agents (reductants).

Loss/Gain of Oxygen/HydrogenExample 1:

Consider the following reactions in which chlorine burns in oxygen to form carbon dioxide andsteam. ( ) + 2 ( ) → ( ) + 2 ( )

Carbon atoms in methane gain oxygen to form carbon dioxide and therefore have beenoxidized.

Oxygen from air has gained hydrogen from methane to form water and thus reduced.

Example 2:

Consider the following reaction: ( ) + ( ) → ( ) + ( ) Hydrogen gains oxygen to become water. Hence, hydrogen under goes oxidation. Copper (II) oxide loses oxygen to form copper metal. Hence, copper (II) oxide in reduced.

Changes in Oxidation StateExample 1:

In the following reaction: ( ) + ( ) → ( ) + ( ) Fe2+ is reduced to Fe as the oxidation state decreases from +2 to 0. Zn is oxidized as its oxidation state is increased from 0 to +2.

Example 2:



Reversible reactions Reversible reactions are those reactions which can take place in both directions. Reversible reactions are represented by . A reversible reaction is in equilibrium when the rates of the forward and reverse reactions are

equal. At equilibrium, the concentrations off reactants and products do not change. For a reversible reaction a catalyst does not alter the equilibrium concentrations of reactants

and products. But it does increase the rate at which the equilibrium is reached.

Factors affecting the Reversible Reactions

Temperature If reaction is exothermic, increase in temperature will favor the backward reaction and yield will

decrease. If reaction in endothermic, increase in temperature will favor the forward reaction and yield will

increase.

Pressure If less number of moles are forming in forward reaction, then increase in pressure will favor the

forward reaction and yield will increase. If more number of moles are forming in the forward reaction, then increase in pressure will

favor the backward reaction and yield will decrease.

Concentration Forward reaction will be favored; if the concentration of the yield is decreased (i.e. yield is taken

out of the system).

The Haber Process - making ammonia and its uses

The reaction to produce ammonia from nitrogen (from air) and hydrogen (from cracking oil) isreversible reaction. + 3 2

The reaction is exothermic reaction. Iron is used as a catalyst in this reaction. In this reaction increase in pressure will increase both the yield of ammonia (because in forward

reaction less number of moles are formed) and the rate of reaction (because of more number ofeffective collusions) so pressure is kept high at 200 ATM.

In this reaction, if we raise the temperature of the system, backward reaction will be favored.Lowering the temperature will favor ammonia production. However at low temperature thereaction will be very slow which is not economical. So Temperature is kept optimum at 450oC.



There are two tests for ammonia gas:It turn red litmus paper blue.It produces white fumes with hydrochloride gas.

Uses of ammonia gasManufacture of Fertilizers Ammonia produced is converted into ammonia compounds

containing large quantity of nitrogen, which are used asfertilizers.Ammonium suphate (NH4)2SO4

Ammonium nitrate NH4NO3

Urea NH2CONH2

Manufacture of Nitric acid Nitric acid is made by the catalytic oxidation of ammoniaover heated platinum.

Bond Energies of Some Covalent BondsUsed for determining the nature of reaction, exothermic or endothermic.

Bond energies of some covalent bondsCovalent bond Bond energy/kJmol-1

H—H 436Cl—Cl 242C—C 348C—H 412O—H 463Cl—H 431N—H 338O=O 496C=O 743NΞN 945C=C 838




The Chemistry and uses of Acids, Bases and Salts Chemistry -5070

The Chemistry and uses ofAcids, Bases and SaltsIn this topic, you will learn: The characteristic properties of acid and bases. Uses of acids and bases. Neutralization and its uses. Different types of oxides. Preparation of salts. Properties and uses of ammonia. Sulphuric acid.



2The Chemistry and uses of Acids, Bases and SaltsAcidsProperties of Acids

Acids form a class of chemical substances which contain hydrogen ions in aqueous solution,H+ (aq), as the only positive ion.

Acid needs water to show its acidic properties. Because hydrogen ions are only formed whenin aqueous state.

Acids turn litmus from blue to red in color. (It is a check of acidity) Acids are electrolytes because in solutions, they are ionic and therefore conduct electricity. If concentrated they can be corrosive. Acids taste sour (for example, vinegar). Acids can be classified into:

Strong acid which ionizes fully in water for example hydrochloric HCl.Weak acid which partially ionize in water for example ethanoic acid CH3COOH.

Reaction of Acids Most dilute acids react with metals to from salt and hydrogen gas.( ) + ( ) → ( ) + ( ) Acids react with metal oxides to form a salt and water.( ) + 2 ( ) → ( ) ( ) + ( ) Acids react with metal hydroxides to form, again, a salt and water.( ) + ( ) → ( ) + ( ) Acids react with metal carbonates to form a salt, water and carbon dioxide.( ) + 2 ( ) → ( ) + ( ) + ( ) Dilute hydrochloric acid is in our stomach which helps digest our food.

Some common acidsType Name Formula Strong or weakMineral Sulphuric acid

Nitric acidHydrochloric acidCarbonic acidSulphurous acidPhosphoric acid

H2SO4

HNO3

HClH2CO3

H2SO3

H3PO4

StrongStrongStrongStrongStrongStrong

Organic Ethanoic acidMethanoic acidLactic acidCitric acid

CH3COOHHCOOH------------C6H8O7

WeakWeakWeakWeak



3The Chemistry and uses of Acids, Bases and SaltsBasesProperties of Bases

Bases form a class of chemical substances which include all metals oxides and metalhydroxides.

A soluble base is called an alkali and in aqueous solutions it produces hydroxide ions (OH-). Alkalis are always metal hydroxide oxides dissolved in water. They feel soapy to touch. They taste bitter. Turn litmus paper from red to blue.

Reactions of Bases When an alkali is added to an acid, it cancels out the acidity, water and salts are products.

This reaction is called neutralization reaction.( ) + ( ) → ( ) + ( ) Acidity of a soil can be lowered by adding a base called calcium hydroxide Ca(OH)2.

Some common alkalis and basesType Common Name Chemical Name FormulaAlkalis Caustic soda

Caustic potashAmmonia solutionSlaked lime

Sodium hydroxidePotassium hydroxideAqueous ammoniaCalcium hydroxide

NaOHKOHNH3(aq)Ca(OH)2

Bases Milk of magnesiaVerdigrisRust

Magnesium oxideCopper(II) oxideIron(III) oxide

MgOCuOFe2O3



4The Chemistry and uses of Acids, Bases and SaltsNeutral Substances Litmus paper is not affected by neutral paper. Tend to be harmless. Water, salt solution are neutral substances.Indicators and pH scale. Indicators are dyes or mixture of dyes which change their color when in acid or alkali. pH is a term used to show the strength of an acid or alkali. The scale runs from 1 to 14. Acids have a pH less than 7, the more acidic a solution, the lower the pH. Alkalis have a pH greater than 7, the more the alkaline a solution, the higher the pH. A neutral substance has pH of 7.

Some common indicator color changeIndicator Color in acid Color in alkaliLitmusUniversalMethyl orangeScreened methyl orangePhenolphthalein

RedRedRedRedColorless

BlueVioletYellowGreenPink



5The Chemistry and uses of Acids, Bases and Salts

NeutralizationIt is a reaction in which an acid reacts with alkali to form salt and water.

Uses of neutralization

Soil Treatment - Farming

The majority of plants grow best at pH 7. If the soil is acidic or alkaline the plant may grow badly.Therefore, chemicals can be added to the soil to change its pH.If the soil is too acidic - the most common complaint - it is treated with a base (chemicals opposite toan acid) in order to neutralize it. Common treatments use quicklime (calcium oxide) or chalk (calciumcarbonate).

The pH values of some common solutionsSubstances pHHydrochloric acid - - - - - - - - -Gastric juices - - - - - - - - - - - - -Lemon juice - - - - - - - - - - - - -Vinegar - - - - - - - - - - - - - - - - -Wine - - - - - - - - - - - - - - - - - - -Tomato juice - - - - - - - - - - - - -Black coffee - - - - - - - - - - - - -Acid rain - - - - - - - - - - - - - - - -Urine - - - - - - - - - - - - - - - - - -Rain Water - - - - - - - - - - - - - -Milk - - - - - - - - - - - - - - - - - - -Pure water - - - - - - - - - - - - - -Blood - - - - - - - - - - - - - - - - - -Baking soda solution - - - - - - -Toothpaste - - - - - - - - - - - - - -Borax solution - - - - - - - - - - - -Milk of Magnesia - - - - - - - - -Limewater - - - - - - - - - - - - - -Ammonia - - - - - - - - - - - - - - -Sodium hydroxide - - - - - - - - -

0.01.02.53.03.54.15.05.66.06.56.57.07.48.59.09.210.511.012.014.0




IndigestionWe all have hydrochloric acid in our stomach - it helps breakdown food! However, too much acidleads to indigestion. Therefore, to cure this ailment we need to neutralize the acid with a base suchas, sodium hydrogen carbonate (baking soda), or an indigestion tablet.

Insect StingsA bee sting contains acid. In order to relieve the painful symptoms of the sting we need toneutralize the acid. By rubbing on calamine lotion (zinc carbonate) or baking soda the acid can beneutralized.Wasp stings are alkaline, hence acid is needed to neutralize and remove the painful sting. Vinegar(ethanoic acid) is used.

Different types Oxides Metal oxides are basic oxides which dissolve in water to form alkalis. Some non-metallic oxides are acidic oxides which dissolve in water to form acids. Some metal oxides can behave as bother acids and bases and so called amphoteric oxides. Some non-metallic oxides neither behaves as acids nor bases are called neutral oxides.

Types of oxides with examplesType Description Name FormulaBasic Metal oxides which

show basic propertiesPotassium oxideSodium oxideCalcium oxideAmmonia

K2ONa2OCaONH3

Acidic Non-metal oxides whichdissolve in water toform acids

Carbon dioxideSulphur DioxidePhosphorus(V) oxide

CO2

SO2

P2O5

P4O10

Amphoteric Metal oxides that canbehave as both acidsand bases

Aluminum oxideZinc oxideLead(II) oxide

Al2O3

ZnOPbO

Neutral Non- metal oxideswhich have neither theproperties of acids norbases

Carbon monoxide CO



7The Chemistry and uses of Acids, Bases and SaltsSalts A salt is the substance formed when the hydrogen of an acid is partly or completely replaced

by a metal.

The patterns of solubility for various types of saltsSalts Soluble InsolubleSodium saltsPotassium saltsAmmonium saltsNitratesEthanoates

All are solubleAll are solubleAll are solubleAll are solubleAll are soluble

NoneNoneNoneNoneNone

Chlorides

Sulphates

Most are soluble- - - - - - - - - -- - - - - - - - - -- - - - - - - - - -Most are soluble- - - - - - - - - -- - - - - - - - - -

Silver chlorideLead(II) chlorideMercury(II) chloride- - - - - - - - - -Calcium sulphateBarium sulphateLead(II) sulphate

Carbonates Sodium carbonatePotassium carbonateAmmonium carbonate

Most are insoluble

Preparation of Soluble SaltsType Equation Suitable forMetal and Acid Metal + Acid→ Salt + Hydrogen Reactive metals

Metal Oxide and Acid Metal oxide + Acid→ Salt + Water Metals which do not react with diluteacids require heating

Metal Hydroxide and Acid Metal hydroxide + Acid→ Salt + Water Soluble metal hydroxidesMetal Carbonate and Acid Metal + Acid→ Salt + Water + Carbon

dioxideDoes not require heating

Titration Acid + Alkali→ Salt + Water Aqueous acid and alkali which producessoluble salt after neutralization reaction.

Identification of cations (positive metal ions)Aqueous

cationAddition of dilute NaOH Addition of dilute NH3

Few drops Excess Few drops ExcessAluminiumAl3+ (aq)

White precipitates Precipitate dissolvesColorless solution

White precipitates Precipitate insoluble

Lead (II)Pb2+ (aq)


White precipitates Precipitate insoluble

ZincZn2+ (aq)



CalciumCa2+ (aq)

White precipitates Precipitate insoluble No reaction No reaction

Copper (II)Cu2+ (aq)

Blue precipitates Precipitate insoluble Blue precipitates Precipitate dissolves




Iron (II)Fe2+ (aq)

Green precipitates Precipitate insoluble Green precipitates Precipitate insoluble

Iron (III)Fe3+ (aq)

Brown precipitates Precipitate insoluble Brown precipitates Precipitate insoluble

AmmoniumNH4

+ (aq)Ammonia gas (NH3) is produced on warmingwith dilute sodium hydroxide. The gas apungent smell and turns damp red litmuspaper blue.

No reaction No reaction

Identification of anions (negative ions)Aqueous anion Test ObservationNitrateNO3

- (aq)Add dilute sodium hydroxideand a little aluminium powder

Ammonia gas is produced

CarbonateCO3

2- (aq)Add dilute hydrochloric acid Effervescence occurs

ChlorideCl- (aq)

Add dilute nitric acid* and thensilver nitrate

A white precipitate of silverchloride is formed

IodideI- (aq)

Add dilute nitric acid* and thenlead(II) nitrate solution

A yellow precipitate of lead(II)iodide is formed

SulphateSO4

2- (aq)Add dilute nitric acid* and thenbarium nitrate solution

A white precipitate of bariumsulphate is formed

*= Nitric acid is added to destroy any carbonate presence

Ammonia and its Uses The reaction to produce ammonia from nitrogen (from air) and hydrogen (from cracking oil)

is reversible reaction. + 3 2 The reaction is exothermic reaction. Iron is used as a catalyst in this reaction. In this reaction increase in pressure will increase both the yield of ammonia (because in

forward reaction less number of moles are formed) and the rate of reaction (because ofmore number of effective collusions) so pressure is kept high at 200 ATM.

In this reaction, if we raise the temperature of the system, backward reaction will befavored. Lowering the temperature will favor ammonia production. However at lowtemperature the reaction will be very slow which is not economical. So Temperature is keptoptimum at 450oC.




There are two tests for ammonia gas:It turn red litmus paper blue.It produces white fumes with hydrochloride gas.

Uses of ammonia gasManufacture ofFertilizers

Ammonia produced is converted into ammonia compoundscontaining large quantity of nitrogen, which are used as fertilizers.Ammonium suphate (NH4)2SO4

Ammonium nitrate NH4NO3

Urea NH2CONH2

Manufacture of Nitricacid

Nitric acid is made by the catalytic oxidation of ammonia overheated platinum.

Sulphuric AcidSulphurSulphur exists as a S8 molecule in which 8 atoms of sulphur join together by covalent bonding. Theintermolecular forces between sulphur are very weak Vander wall’s forces. Due to these weak forcessulphur has a low melting and boiling point. There are three major sources of sulphur.

Volcanic regionsNative sulphur is found in volcanic regions.

Oil gasNatural gas and crude oil are contaminated with sulphur

MineralsSome mineral ores contain sulphur.

Oxides of SulphurThere are two possible oxides of sulphur, called sulphur dioxide (SO2) and sulphur trioxide (SO3).

Sulphur DioxideSulphur burns in air with a blue flame, forming sulphur dioxide:( ) + 2( ) ( )It is an acidic gas with a choking smell.

Sulphur dioxide has many uses.

Manufacture of sulphurous acid (H2SO3) Manufacture of sulphuric acid (H2SO4) Used as a preservative ( by killing bacteria) Used to sterilize things Used to bleach wood pulp before making paper.

Sulphur trioxideSulphur trioxide is formed by reaction between sulphur dioxide and oxygen.




2 ( ) + 2( ) ⇄ 2 ( )Manufacture of Sulphuric acid

1. Sulphur dioxide is produced by burning sulphur.S(s) + O2(g) SO2(g)2. The sulphur dioxide is purified.3. Sulphur dioxide is reacted with oxygen over a vanadium(V) oxide catalyst.2 2( ) + 2( ) ⇄ 2 3( )

This reaction is exothermic, which means it favors a low temperature for high yield ofsulphur dioxide. However if temperature is lowered rate of reaction slows down. Accordinglyan average temperature of 450oC is used. Pressure is kept low at 2 ATM.

4. Sulphur trioxide is dissolved in concentrated sulphuric acid to form oleum.( ) + ( ) → ( )5. This oleum is diluted with water to form sulphuric acid.( ) + ( ) → 2 ( )

Uses of Sulphuric Acid Sulphur is used for the production of fertilizers such as ammonia sulphate, potassium

sulphate and calcium sulphate, e.t.c. Used for manufacture of non-soapy-detergents. Used for making of artificial silks like rayon. Used as cleaning metals by removing surface oxide coating. Used as an electrolyte in batteries.




The Periodic Table of Elements Chemistry - 5070

The Periodic Table ofElementsIn this topic, you will learn:



The Periodic Table of Elements In Periodic table elements are arranged in order of their increasing proton number. It was invented in 1869 be a Russian chemist by the name Mendeleev. Vertical columns are called groups. Horizontal rows are called periods. Group number indicates the no of valence electrons. Period number indicates the no of electron shells. On left side of periodic table are metals. On right side of periodic table are non-metals. Between group 2 and 3 are transition metals. On the extreme right-hand side are inert gases, which have 2 or 8 valence electrons.

Metals and Non-Metals: Across a Period In a periodic table metals and non-metals can be identified by staircase line. Left to the line are

metals and right are non-metals. Elements close to staircase line are called Metalloids. They have properties of both metals and

non-metals. Metalloids beneath the staircase line are poor metals.

Differences between metals and non-metalsMetals Non-MetalsGood conductors of heat and electricity Poor conductors of heat and electricityUsually solids at room temperature (except Hg) Often gases (except Br, S, P, I, C, B and Si)High melting and boiling points (except Group I) Low melting and boiling points (except B, C and Si)Often shiny, ductile, malleable and possess greattensile strength Normally dull, soft and cannot be drawn out into

wires or made into flat sheetsMostly compounds are ionic Mostly compounds are covalentOxides are usually basic or amphoteric Oxides are usually neutral or acidic



Often form hydrogen gas with dilute acids Never form hydrogen gas from acidsAlways form positive ions (cations) Always form negative ions (anions)

Group I: Alkali Metals Very reactive metals. Reactivity increases as we go down the group (As we go down the group the size of atom

increases with the increase in number of shells thus the distance of valence electrons from thenucleus increases. This makes easier to lose the valence electron.

Unlike other metals Group I metals are silvery, soft, have low density, melting point and boilingpoint.

Good thermal and electrical conductors. They react very violently with Oxygen or air, burning and catching fire with characteristic flame

color and forming white oxide. For example:4 + → 2That is why Group I metals are stored in oil to prevent reaction with air or oxygen.

These metal oxides are basic oxides (basic oxides dissolve in water to form alkali). They react very vigorously with water forming metal hydroxide and hydrogen gas.4 + 2 → 2 + Their reaction with halogen is very quick forming white solid.+ →

Properties of Group I ElementsElement Melting point/ oC Boiling point/ oC Density/gcm-3Lithium 181 1342 0.53Sodium 98 883 0.97Potassium 63 760 0.86Rubidium 39 686 1.53Caesium 29 669 1.90

Group VII: The Halogens Very reactive non-metals. Their reactivity decreases down the group (this can be explained by atomic size, which increases

down the group. It therefore makes it more difficult for the nucleus to attract an electron toform an ion).

They all are poisonous and have a similar strong smell. All halogen form single negative charges when reacted with metals. These charged ions are

called halides. They exists as diatomic molecules (two atoms combined together covalently) for example Cl2

and Br2.



Halogens form ions with single negative charge (F-, Cl-, Br- and I-). Any halogen above another halogen in the group will displace it from a solution of its salt

(because reactivity of halogens decreases as we go down the Group).Such reactions are calleddisplacement reactions. + 2 → 2 +

Low melting point and boiling point. As we go down the group density increases. Their melting point and boiling point increases as we go down the group. This is because melting

point and boiling point depends on the intermolecular forces of attraction. These forces increasewhen the size of molecules increases.

Uses of Group VII ElementsElement UsesFluorine Prevents tooth decay, put into tap water and

toothpastes.Chlorine Kill germs and harmful micro-organisms, put in tapand pool water.Iodine Very small amount of iodine is required in humanbodies. Deficiency cause swelling in neck.

Physical Properties of Group VII ElementsChlorine Bromine Iodine

Color Yellowish green Reddish-brown Grey/BlackState at roomtemperature

Gas Volatile liquid Solid

Other properties Molecules are spacedfar apart and aremoving at high speeds

Has low boiling point(59oC) and easilychange into vapors

Sublimes at gentleheating. Purple colorwhen liquid.

Uses Water TreatmentBleach

PesticidesPhotographic film

AntisepticsPhotographic film

Group O or VIII: Noble Gases Eighth group is of noble gases. These gases are inert i.e. they do not take part in chemical reaction. This is because their

outermost shell is complete with eight electrons. They exist as monoatomic gases (uncombined atoms) for example He, Ne, Ar, Kr, Xe and Rn) Can be used to provide inert atmosphere for example neon and argon in light bulbs; helium in

balloons; argon in manufacture of steel. They have very low melting and boiling points.



Their boiling point and melting point increases as we go down the group, the reason behind isthat as we go down the group size to atom increases and so does the Vander Wall’s force ofattraction.

Name Symbol B.p. (oC) UsesHelium He -269 In airships, hot gas balloonsNeon Ne -246 In advertising lightsArgon Ar -185 An inert gas for electric bulbs, welding and making steelKrypton Kr -153 Gas-filled electronic devices and lasersXenon Xe -109 Electronic flash gunsRadon Rn -62 Natural radioactive gas

Transition Metals: Typical Metals Metals between group 2 and group 3 are called transition metals. They are typical metals. Transition metals are not so reactive. Transition metals are colored compounds.

Transition metal Color of compoundCopper(II) compounds BlueIron(II) compounds GreenIron(III) compounds BrownLead(II) compounds WhiteZinc(II) compounds White

They have variable valency (or oxidation state). For example Iron(II) and Iron(III). They are strong and hard metals. They have high melting points, boiling points and densities. Tungsten has melting point of

3410oC and is used as a filament in filament bulbs. They are good conductors of heat and electricity. Transition metals have catalytic properties (they can be used to speed up reactions).

Industrial Process Transition metal used as catalystContact Process Vanadium(V) oxide to help the conversion to

sulphur trioxideHaber Process Iron to make ammonia gasMargarine manufacture Nickel in hydrogenation of alkene

Transition Metal Properties and UsesChromium Hard, unreactive and attractive. Used for



Chromium plating and in making stainless steelTitanium Light but as strong as steel. Used in air craft

constructionCopper Unreactive and malleable. Used in electrical wires

and water-piping.Zinc Grey metal with a blue tingle. Used to galvanize

iron to prevent it from rusting.Nickel Strong metal and resists corrosion. Used in stain

less steel.Manganese Hard metal. Used to harden steel.Tungsten Very high melting point of 3410oC. Used in

filament bulb as filament.




Metals Chemistry - 5070

MetalsIn this topic, you will learn: Position of metals in Periodic Table Properties of metals Extremes in metals Alloys and composition of some common alloys



Metals in Periodic Table Metals are found from Group I to Group III of the Periodic Table. Metals between group II and III are typical metals known as transition metals.

Properties of Metals High Density

Due to close packing of atoms on metals. High Melting Point

Strong forces of attraction between atoms cause high melting point of metals. Malleable and Ductile

Malleable means metals can change shape without breaking.Ductile means metals can be made into wires.When force is applied to a metal, the atoms can slip over one another. This allows the metal tobe malleable and ductile.

Thermal ConductivityVibration of atoms and outermost electrons helps transfer of heat energy.

Electrical ConductivityFree outermost electron cause metal to conduct electricity. When a metal is connected into acircuit the electrons move towards the positive terminal, and electrons form the negativeterminal flow to the metals to replace them.

Extremes in MetalsLightest Lithium (Li) has a density of 0.53 g cm-3

Heaviest Osmium (Os) has a density of 22.48 g cm-3

Most brittle Manganese (Mn) and chromium (Cr) are most brittleLowest melting point Mercury (Hg) has melting point of -38.9 °CHighest melting point Tungsten (W) has a melting points of +3410 °CMost expensive Platinum (pt) has the greatest commercial valueRarest Rhodium (Rh) is the rarest natural metal on earthMost abundant Aluminum (Al) makes up over 8%of the earth’s crust



Alloy and it’s Properties Alloys are mixture of different metals. Some times non-metals

may also be added. Alloys are harder than pure metals this is because larger atoms

stop the layers of other metals from sliding over each other. Alloys are less corrosive.

Come common alloysAlloy Approximate composition UsesSteel 99% Fe, 1% C Ships, bridgesCupronickel 75% Cu, 25% Ni Silver coinsBronze 90% Cu, 10% Sn Medals, swords, statuesBrass 70% Cu, 30% Zn Ornaments, electrical wiring and

contactsSolder 70 % Pb, 30% Sn Joining metalsPewter 70% Sn, 30% Pb Drinking mugsConstantan 60% Cu, 40% Ni ThermocouplesMagnalium 70% Al, 30% Mg Aircraft framesDuralumin 95% Al, 5% Cu/Mg ConstructionAmalgams Hg/Sn alloys Filling in teeth

The Reactivity Series of MetalsName Symbol DetailPotassium K Reactivity decreases down as we go down.Sodium NaCalcium CaMagnesium Mg

Stability of Ion decreases as we go down.Aluminum AlZinc ZnIron FeLead PbCopper Cu

Ease of discharge decreases as we godown.

Mercury HgSilver AgPlatinum Pt



As more reactive metals have greater tendencies for oxidation thus they immediately convertinto their respective ions. So it can be concluded that ions formed by more reactive metal aremore stable and are difficult to discharge.

Learning aid for reactivity series. First letter of following statement represent the first letter ofthe name of element.Please Send Cats Monkeys And Zebras In Large Cages Make Sure Pet-locked.

Reaction of metals with waterName of Metal Metal with water or steam ProductsPotassium React with cold water Solution of their hydroxide and

hydrogen gas.SodiumCalciumMagnesium React with steam Oxides of these metals and

hydrogen gas.AluminumzincIronLead No reaction with water or steam No reaction.CopperMercurySilverPlatinum

For example: 2 + 2 → 2 ++ → +Reaction of metals with acidName of Metal Metal with acid ProductsPotassium Violent reaction with dilute acid. Salt and hydrogen gas.SodiumCalciumMagnesium React with dilute acids with

decreasing ease.Salt and hydrogen gas.

AluminumzincIronLeadCopper React only with concentrated

acids.Salt and hydrogen gas.

MercurySilverPlatinum



For example: 2 + 2 → ++ 2 → +Stability of Metal CompoundsThe stability of metal compoundsMetal Oxide Hydroxide Carbonate NitratePotassium Electrolytic

reductionStable to heat Stable to heat Decompose to

nitrate and oxygenSodiumCalcium Decompose to

metal oxide andsteam on heating

Decompose tometal oxide andcarbon dioxide gason heating

Decompose tometal oxide,nitrogen dioxideand oxygen onheating

MagnesiumAluminumZinc Reduced by

heating withcarbon

IronLeadCopperMercury Reduced by

heating aloneUnstable, do notexist

Unstable, do notexist

Decompose tometal, oxygen andnitrogen dioxidegas on heating

SilverPlatinumThe Displacement Power of Metals

Any metal above another in the reactivity series is capable of displacing it for its oxide, or froman aqueous solution of its salt.

Thermit reaction:( ) + → ++ 2 → + 2 This reaction needs a magnesium fuse to start the reaction. The reaction is extremely exothermic so the iron produced is molten. It is used to weld railway line.

Displacement from Solutions




Organic Chemistry Chemistry - 5070

Organic ChemistryIn this topic, you will learn: Under Progress



Organic Chemistry? Work Under Progress




Glossary Chemistry -5070GlossaryA

Acid a substance that produces hydrogen ions in aqueous solution; a proton donor.

Acid - base indicator a substance that marks the end point of an acid - base titration by changing color.

Acid rain rainwater with an acidic pH, a result of air pollution by sulfur dioxide and nitrogen oxides.

Acidic oxide a covalent oxide that dissolves in water to give an acidic solution.

Actinide series a group of fourteen elements following actinium on the periodic table, in which the 5forbitals are being filled.

Activation energy the threshold energy that must be overcome to produce a chemical reaction.

Air pollution contamination of the atmosphere, mainly by the gaseous products of transportation andthe production of electricity.

Alcohol an organic compound in which the hydroxyl group is a substituent on a hydrocarbon.

Aldehyde an organic compound containing the carbonyl group bonded to at least one hydrogen atom.

Alkali metal a Group 1 metal.

Alkaline earth metal a Group 2 metal.

Alkane a saturated hydrocarbon with the general formula CnH2n12.

Alkene an unsaturated hydrocarbon containing a carbon - carbon double bond. The general formula isCnH2n.

Alkyne an unsaturated hydrocarbon containing a carbon - carbon triple bond. The general formula isCnH2n22.

Alloy a substance that contains a mixture of elements and has metallic properties.

Alloy steel a form of steel containing carbon plus metals such as chromium, cobalt, manganese, andmolybdenum.




Glossary Chemistry -5070

Alpha ( ) particle a helium nucleus produced in radioactive decay.

Alpha-particle production a common mode of decay for radioactive nuclides in which the massnumber changes.

Amine an organic base derived from ammonia in which one or more of the hydrogen atoms arereplaced by organic groups.

-Amino acid an organic acid in which an amino group, a hydrogen atom, and an R group areattached to the carbon atom next to the carboxyl group.

Ampere the unit of measurement for electric current; 1 ampere is equal to 1 coulomb of charge persecond.

Amphoteric substance a substance that can behave either as an acid or as a base.

Anion a negative ion.

Anode in a galvanic cell, the electrode at which oxidation occurs.

Aqueous solution a solution in which water is the dissolving medium, or solvent.

Aromatic hydrocarbon one of a special class of cyclic unsaturated hydrocarbons, the simplest ofwhich is benzene.

Arrhenius concept a concept postulating that acids produce hydrogen ions in aqueous solution,whereas bases produce hydroxide ions.

Atmosphere the mixture of gases that surrounds the earth's surface.Atom the fundamental unit of which elements are composed.

Atomic mass (weight) the weighted average mass of the atoms in a naturally occurring element.

Atomic number the number of protons in the nucleus of an atom; each element has a unique atomicnumber.

Atomic radius half the distance between the atomic nuclei in a molecule consisting of identical atoms.

Atomic solid a solid that contains atoms at the lattice points.

Aufbau principle a principle stating that as protons are added one by one to the nucleus to build upthe elements, electrons are similarly added to hydrogen-like orbitals.





Auto-ionization the transfer of a proton from one molecule to another of the same substance.

Avogadro's law equal volumes of gases at the same temperature and pressure contain the samenumber of particles (atoms or molecules).

Avogadro's number the number of atoms in exactly 12 grams of pure 12C, equal to 6.02 x 1023.

B

Ball-and-stick model a molecular model that distorts the sizes of atoms but shows bond relationshipsclearly.

Barometer a device for measuring atmospheric pressure.

Base a substance that produces hydroxide ions in aqueous solution; a proton acceptor.

Basic oxide an ionic oxide that dissolves in water to produce a basic solution.

Battery a group of galvanic cells connected in series.

Beta ( ) particle an electron produced in radioactive decay.

Beta-particle production a decay process for radioactive nuclides in which the mass number remainsconstant and the atomic number increases by one.The net effect is to change a neutron to a proton.

Binary compound a two-element compound.

Binding energy (nuclear) the energy required to decompose a nucleus into its component nucleons.

Biochemistry the study of the chemistry of living systems.

Biomolecule a molecule that functions in maintaining and/or reproducing life.

Bond (chemical bond) the force that holds two atoms together in a compound.

Bond energy the energy required to break a given chemical bond.





Bond length the distance between the nuclei of the two atoms that are connected by a bond.

Bonding pair an electron pair found in the space between two atoms.

Boyle's law the volume of a given sample of gas at constant temperature varies inversely with thepressure.

Breeder reactor a nuclear reactor in which fissionable fuel is produced while the reactor runs.

Brønsted - Lowry model a model proposing that an acid is a proton donor and that a base is a protonacceptor.

Buffer capacity the ability of a buffered solution to absorb protons or hydroxide ions without asignificant change in pH.

Buffered solution a solution that resists a change in its pH when either hydroxide ions or protons areadded.

Buret a device for the accurate measurement of the delivery of a given volume of liquid.

C

Calorie a unit of measurement for energy; one calorie is the quantity of energy required to heat onegram of water by one Celsius degree.

Calorimetry the science of measuring heat flow.

Carbohydrate a polyhydroxyl ketone or polyhydroxyl aldehyde or a polymer composed of these.

Carbon steel an alloy of iron containing up to about 1.5% carbon.

Carboxyl group the COOH group in an organic acid.

Carboxylic acid an organic compound containing the carboxyl group.

Catalyst a substance that speeds up a reaction without being consumed.

Cathode in a galvanic cell, the electrode at which reduction occurs.





Cathode rays the "rays" emanating from the negative electrode (cathode) in a partially evacuatedtube; a stream of electrons.

Cathodic protection the connection of an active metal, such as magnesium, to steel to protect thesteel from corrosion.

Cation a positive ion.

Cell potential (electromotive force) the driving force in a galvanic cell that pushes electrons fromthe reducing agent in one compartment to the oxidizing agent in the other.

Chain reaction (nuclear) a self-sustaining fission process caused by the production of neutrons thatproceed to split other nuclei.

Charles's law the volume of a given sample of gas at constant pressure is directly proportional to thetemperature in kelvins.

Chemical change the change of substances into other substances through a reorganization of theatoms; a chemical reaction.

Chemical equation a representation of a chemical reaction showing the relative numbers of reactantand product molecules.

Chemical equilibrium a dynamic reaction system in which the concentrations of all reactants andproducts remain constant as a function of time.

Chemical formula a representation of a molecule in which the symbols for the elements are used toindicate the types of atoms present and subscripts are used to show the relative numbers of atoms.

Chemical kinetics the area of chemistry that concerns reaction rates.

Chemical property the ability of a substance to change to a different substance.

Chemical stoichiometry the quantities of materials consumed and produced in a chemical reaction.

Colligative property a solution property that depends on the number of solute particles present.

Collision model a model based on the idea that molecules must collide to react; used to account forthe observed characteristics of reaction rates.

Combustion reaction the vigorous and exothermic oxidation - reduction reaction that takes place





between certain substances (particularly organic compounds) and oxygen.

Complete ionic equation an equation that shows as ions all substances that are strong electrolytes.

Compound a substance with constant composition that can be broken down into elements by chemicalprocesses.

Condensation the process by which vapor molecules re-form a liquid.

Condensed states of matter liquids and solids.

Conjugate acid the species formed when a proton is added to a base.

Conjugate acid - base pair two species related to each other by the donating and accepting of a singleproton.

Conjugate base what remains of an acid molecule after a proton is lost.

Continuous spectrum a spectrum that exhibits all the wavelengths of visible light.

Control rods in a nuclear reactor, rods composed of substances that absorb neutrons.These rods regulate the power level of the reactor.

Core electron an inner electron in an atom; one that is not in the outermost (valence) principalquantum level.

Corrosion the process by which metals are oxidized in the atmosphere.

Covalent bonding a type of bonding in which atoms share electrons.

Critical mass the mass of fissionable material required to produce a self-sustaining chain reaction.

Critical reaction (nuclear) a reaction in which exactly one neutron from each fission event causesanother fission event, thus sustaining the chain reaction.

Crystalline solid a solid characterized by the regular arrangement of its components.

D





Dalton's law of partial pressures for a mixture of gases in a container, the total pressure exerted isthe sum of the pressures that each gas would exert if it were alone.

Denaturation the breaking down of the three-dimensional structure of a protein, resulting in the lossof its function.

Density a property of matter representing the mass per unit volume.

Deoxyribonucleic acid (DNA) a huge nucleotide polymer having a double-helical structure withcomplementary bases on the two strands.Its major functions are protein synthesis and the storage and transport of genetic information.

Diatomic molecule a molecule composed of two atoms.

Dilution the process of adding solvent to lower the concentration of solute in a solution.

Dipole - dipole attraction the attractive force resulting when polar molecules line up such that thepositive and negative ends are close to each other.

Dipole moment a property of a molecule whereby the charge distribution can be represented by acenter of positive charge and a center of negative charge.

Disaccharide a sugar formed from two monosaccharides joined by a glycoside linkage.

Distillation a method for separating the components of a liquid mixture that depends on differences inthe ease of vaporization of the components.

Double bond a bond in which two atoms share two pairs of electrons.

Dry cell battery a common battery used in calculators, watches, radios, and tape players.

E

Electrical conductivity the ability to conduct an electric current.

Electrochemistry the study of the interchange of chemical and electrical energy.

Electrolysis a process that involves forcing a current through a cell to cause a nonspontaneouschemical reaction to occur.





Electrolyte a material that dissolves in water to give a solution that conducts an electric current.

Electrolytic cell a cell that uses electrical energy to produce a chemical change that would nototherwise occur.

Electromagnetic radiation radiant energy that exhibits wave-like behavior and travels through spaceat the speed of light in a vacuum.

Electron a negatively charged particle that occupies the space around the nucleus of an atom.

Electronegativity the tendency of an atom in a molecule to attract shared electrons to itself.

Element a substance that cannot be decomposed into simpler substances by chemical or physicalmeans. It consists of atoms all having the same atomic number.

Empirical formula the simplest whole-number ratio of atoms in a compound.

End point the point in a titration at which the indicator changes color.

Endothermic refers to a reaction in which energy (as heat) flows into the system.

Energy the capacity to do work or to cause the flow of heat.

Enthalpy at constant pressure, the change in enthalpy equals the energy flow as heat.

Enzyme a large molecule, usually a protein, that catalyzes biological reactions.

Equilibrium constant the value obtained when equilibrium concentrations of the chemical species aresubstituted into the equilibrium expression.

Equilibrium expression the expression (from the law of mass action) equal to the product of theproduct concentrations divided by the product of the reactant concentrations, each concentrationhaving first been raised to a power represented by the coefficient in the balanced equation.

Equilibrium position a particular set of equilibrium concentrations.

Equivalence point (stoichiometric point) the point in a titration when enough titrant has beenadded to react exactly with the substance in solution that is being titrated.

Essential elements the elements known to be essential to human life.





Ester an organic compound produced by the reaction between a carboxylic acid and an alcohol.

Exothermic refers to a reaction in which energy (as heat) flows out of the system.

Exponential notation expresses a number in the form N 3 10M; a convenient method for representinga very large or very small number and for easily indicating the number of significant figures.

F

Fat (glyceride) an ester composed of glycerol and fatty acids.

Fatty acid a long-chain carboxylic acid.

Filtration a method for separating the components of a mixture containing a solid and a liquid.

First law of thermodynamics a law stating that the energy of the universe is constant.

Fission the process of using a neutron to split a heavy nucleus into two nuclei with smaller massnumbers.

Fossil fuel a fuel that consists of carbon-based molecules derived from decomposition of once-livingorganisms; coal, petroleum, or natural gas.

Frequency the number of waves (cycles) per second that pass a given point in space.

Fuel cell a galvanic cell for which the reactants are continuously supplied.

Functional group an atom or group of atoms in hydrocarbon derivatives that contains elements inaddition to carbon and hydrogen.

Fusion the process of combining two light nuclei to form a heavier, more stable nucleus.

G

Galvanic cell a device in which chemical energy from a spontaneous oxidation - reduction reaction ischanged to electrical energy that can be used to do work.





Galvanizing a process in which steel is coated with zinc to prevent corrosion.

Gamma ( ) ray a high-energy photon produced in radioactive decay.

Gas one of the three states of matter; has neither fixed shape nor fixed volume.Geiger - Müller counter (Geiger counter) an instrument that measures the rate of radioactive decayby registering the ions and electrons produced as a radioactive particle passes through a gas-filledchamber.

Gene a given segment of the DNA molecule that contains the code for a specific protein.

Greenhouse effect a warming effect exerted by certain molecules in the earth's atmosphere(particularly carbon dioxide and water).

Ground state the lowest possible energy state of an atom or molecule.

Group (of the periodic table) a vertical column of elements having the same valence electronconfiguration and similar chemical properties.

H

Haber process the manufacture of ammonia from nitrogen and hydrogen, carried out at high pressureand high temperature with the aid of a catalyst.

Half-life (of a radioactive sample) the time required for the number of nuclides in a radioactivesample to reach half the original number of nuclides.

Half-reactions the two parts of an oxidation - reduction reaction, one representing oxidation, theother reduction.

Halogen a Group 7 element.

Hard water water from natural sources that contains relatively large concentrations of calcium andmagnesium ions.

Heat energy transferred between two objects because of a temperature difference between them.

Heating/cooling curve a plot of temperature versus time for a substance, where energy is added at aconstant rate.





Heisenberg uncertainty principle a principle stating that there is a fundamental limitation to howprecisely we can know both the position and the momentum of a particle at a given time.

Herbicide a pesticide applied to kill weeds.

Heterogeneous equilibrium an equilibrium involving reactants and/or products in more than onestate.

Heterogeneous mixture a mixture that has different properties in different regions of the mixture.

Heterogeneous reaction reaction involving reactants in different phases.

Homogeneous equilibrium an equilibrium system in which all reactants and products are in the samestate.

Homogeneous mixture a mixture that is the same throughout; a solution.

Homogeneous reaction reaction involving reactants in only one phase.

Hydration the interaction between solute particles and water molecules.

Hydrocarbon a compound of carbon and hydrogen.

Hydrocarbon derivative an organic molecule that contains one or more elements in addition tocarbon and hydrogen.

Hydrogen bonding unusually strong dipole - dipole attractions that occur among molecules in whichhydrogen is bonded to a highly electronegative atom.

Hydronium ion the H3O1 ion; a hydrated proton.

Hypothesis one or more assumptions put forth to explain observed phenomena.

I

Ideal gas a hypothetical gas that exactly obeys the ideal gas law.A real gas approaches ideal behavior at high temperature and/or low pressure.





Ideal gas law an equation relating the properties of an ideal gas, expressed as PV 5 nRT, where P 5pressure, V 5 volume, n 5 moles of the gas, R 5 the universal gas constant, and T 5 temperature on theKelvin scale.This equation expresses behavior closely approached by real gases at high temperature and/or lowpressure.

Indicator a chemical that changes color and is used to mark the end point of a titration.

Intermolecular forces relatively weak interactions that occur between molecules.

Internal energy the sum of the kinetic and potential energies of all components of an object.

Intramolecular forces interactions that occur within a given molecule.

Ion an atom or a group of atoms that has a net positive or negative charge.

Ion-product constant (Kw) the equilibrium constant for the auto-ionization of water; Kw 5[H1][OH2]. At 25 C, Kw equals 1.0 3 10214.

Ionic bonding the attraction between oppositely charged ions.

Ionic compound a compound that results when a metal reacts with a nonmetal to form cations andanions.

Ionic solid a solid containing cations and anions that dissolves in water to give a solution containing theseparated ions, which are mobile and thus free to conduct an electric current.

Ionization energy the quantity of energy required to remove an electron from a gaseous atom or ion.

Isomers species that have the same chemical formula but different properties.

Isotopes atoms of the same element (the same number of protons) that have different numbers ofneutrons.They have identical atomic numbers but different mass numbers.

J

Joule a unit of measurement for energy; 1 calorie 5 4.184 joules.





K

Ketone an organic compound containing the carbonyl group bonded to two carbon atoms.

Kinetic energy 112mv22 energy due to the motion of an object; dependent on the mass of the objectand the square of its velocity.

Kinetic molecular theory a model that assumes that an ideal gas is composed of tiny particles(molecules) in constant motion.

L

Lanthanide series a group of fourteen elements following lanthanum on the periodic table, in whichthe 4f orbitals are being filled.

Lattice a three-dimensional system of points designating the positions of the centers of thecomponents of a solid (atoms, ions, or molecules).

Law of chemical equilibrium a general description of the equilibrium condition; it defines theequilibrium expression.

Law of conservation of energy energy can be converted from one form to another but can be neithercreated nor destroyed.

Law of conservation of mass mass is neither created nor destroyed.

Law of constant composition a given compound always contains elements in exactly the sameproportion by mass.

Law of mass action (also called the law of chemical equilibrium) a general description of theequilibrium condition; it defines the equilibrium expression.

Law of multiple proportions a law stating that when two elements form a series of compounds, theratios of the masses of the second element that combine with one gram of the first element can alwaysbe reduced to small whole numbers.

Lead storage battery a battery (used in cars) in which the anode is lead, the cathode is lead coated





with lead dioxide, and the electrolyte is a sulfuric acid solution.Le Châtelier's principle if a change is imposed on a system at equilibrium, the position of theequilibrium will shift in a direction that tends to reduce the effect of that change.

Lewis structure a diagram of a molecule showing how the valence electrons are arranged among theatoms in the molecule.

Limiting reactant (limiting reagent) the reactant that is completely consumed when a reaction isrun to completion.

Line spectrum a spectrum showing only certain discrete wavelengths.

Linear accelerator a type of particle accelerator in which a changing electrical field is used toaccelerate a beam of charged particles along a linear path.

Lipids water-insoluble substances that can be extracted from cells by nonpolar organic solvents.

Liquid one of the three states of matter; has a fixed volume but takes the shape of its container.

London dispersion forces the relatively weak forces, which exist among noble gas atoms andnonpolar molecules, that involve an accidental dipole that induces a momentary dipole in a neighbor.

Lone pair an electron pair that is localized on a given atom; an electron pair not involved in bonding.

M

Main-group (representative) elements elements in the groups labeled 1,2,3,4,5,6,7, and 8 on theperiodic table.The group number gives the sum of the valence s and p electrons.

Mass the quantity of matter in an object.

Mass number the total number of protons and neutrons in the atomic nucleus of an atom.

Mass percent the percent by mass of a component of a mixture or of a given element in a compound.

Matter the material of the universe.

Metal an element that gives up electrons relatively easily and is typically lustrous, malleable, and a good





conductor of heat and electricity.

Metalloid an element that has both metallic and nonmetallic properties.

Metallurgy the process of separating a metal from its ore and preparing it for use.

Millimeters of mercury (mm Hg) a unit of measurement for pressure, also called a torr; 760 mm Hg5 760 torr 5 101,325 Pa 5 1 standard atmosphere.

Mixture a material of variable composition that contains two or more substances.

Model (theory) a set of assumptions put forth to explain the observed behavior of matter.The models of chemistry usually involve assumptions about the behavior of individual atoms ormolecules.

Moderator a substance used in a nuclear reactor to slow down the neutrons.

Molar heat of fusion the energy required to melt 1 mol of a solid.

Molar heat of vaporization the energy required to vaporize 1 mol of a liquid.

Molar mass the mass in grams of one mole of a compound.

Molar volume the volume of one mole of an ideal gas; equal to 22.42 liters at standard temperature and pressure.

Molarity moles of solute per volume of solution in liters.

Mole (mol) the number equal to the number of carbon atoms in exactly 12 grams of pure 12C:Avogadro's number. One mole represents 6.02 x 1023 units.

Mole ratio (stoichiometry) the ratio of moles of one substance to moles of another substance in abalanced chemical equation.

Molecular equation an equation representing a reaction in solution and showing the reactants andproducts in undissociated form, whether they are strong or weak electrolytes.

Molecular formula the exact formula of a molecule, giving the types of atoms and the number of eachtype.

Molecular solid a solid composed of small molecules.





Molecular structure the three-dimensional arrangement of atoms in a molecule.

Molecular weight (molar mass) the mass in grams of one mole of a substance.

Molecule a bonded collection of two or more atoms of the same element or different elements.

Monoprotic acid an acid with one acidic proton.

N

Natural gas consists of mostly methane and is associated with petroleum deposits.

Natural law a statement that expresses generally observed behavior.

Net ionic equation an equation for a reaction in solution, representing strong electrolytes as ions andshowing only those components that are directly involved in the chemical change.

Network solid an atomic solid containing strong directional covalent bonds.

Neutralization reaction an acid - base reaction.

Neutron a particle in the atomic nucleus with a mass approximately equal to that of the proton butwith no charge.

Noble gas a Group 8 element.

Nonelectrolyte a substance that, when dissolved in water, gives a nonconducting solution.

Nonmetal an element that does not exhibit metallic characteristics.Chemically, a typical nonmetal accepts electrons from a metal.

Normal boiling point the temperature at which the vapor pressure of a liquid is exactly oneatmosphere; the boiling temperature under one atmosphere of pressure.

Normal melting/freezing point the melting/freezing point of a solid at a total pressure of oneatmosphere.

Normality the number of equivalents of a substance dissolved in a liter of solution.





Nuclear atom the modern concept of the atom as having a dense center of positive charge (thenucleus) and electrons moving around the outside.

Nuclear transformation the change of one element into another.

Nucleon a particle in an atomic nucleus, either a neutron or a proton.

Nucleus the small, dense center of positive charge in an atom.

Nuclide the general term applied to each unique atom; represented by AZX, where X is the symbol for aparticular element.

O

Octet rule the observation that atoms of nonmetals form the most stable molecules when they aresurrounded by eight electrons (to fill their valence orbitals).

Orbital a representation of the space occupied by an eletron in an atom; the probability distribution forthe electron.

Organic acid an acid with a carbon-atom backbone and a carboxyl group.

Organic chemistry the study of carbon-containing compounds (typically containing chains of carbonatoms) and their properties.

Oxidation an increase in oxidation state (a loss of electrons).

Oxidation - reduction (redox) reaction a reaction in which one or more electrons are transferred.

Oxidation states a concept that provides a way to keep track of electrons in oxidation - reductionreactions according to certain rules.

Oxidizing agent (electron acceptor) a reactant that accepts electrons from another reactant.

Oxyacid an acid in which the acidic proton is attached to an oxygen atom.

Ozone O3, a form of elemental oxygen much less common than O2 in the atmosphere near the earth.





P

Partial pressures the independent pressures exerted by different gases in a mixture.

Particle accelerator a device used to accelerate nuclear particles to very high speeds.

Pascal the SI unit of measurement for pressure; equal to one newton per square meter.

Percent yield the actual yield of a product as a percentage of the theoretical yield.

Periodic table a chart showing all the elements arranged in columns in such a way that all theelements in a given column exhibit similar chemical properties.

Petroleum a thick, dark liquid composed mostly of hydrocarbon compounds.pH scale a log scale based on 10 and equal to 2log[H1]; a convenient way to represent solution acidity.

Phenyl group the benzene molecule minus one hydrogen atom.

Photochemical smog air pollution produced by the action of light on oxygen, nitrogen oxides, andunburned fuel from auto exhaust to form ozone and other pollutants.

Photon a "particle" of electromagnetic radiation.

Physical charge a change in the form of a substance, but not in its chemical nature; chemical bondsare not broken in a physical change.

Physical property a characteristic of a substance that can change without the substance becoming adifferent substance.

Polar covalent bond a covalent bond in which the electrons are not shared equally because one atomattracts them more strongly than the other.

Polar molecule a molecule that has a permanent dipole moment.

Polyatomic ion an ion containing a number of atoms.

Polyelectronic atom an atom with more than one electron.

Polymer a large, usually chain-like molecule built from many small molecules (monomers).





Polymerization a process in which many small molecules (monomers) are joined together to form alarge molecule.

Polyprotic acid an acid with more than one acidic proton.It dissociates in a stepwise manner, one proton at a time.

Positron production a mode of nuclear decay in which a particle is formed that has the same mass asan electron but opposite charge.The net effect is to change a proton to a neutron.

Potential energy energy due to position or composition.

Precipitation reaction a reaction in which an insoluble substance forms and separates from thesolution as a solid.

Precision the degree of agreement among several measurements of the same quantity; thereproducibility of a measurement.

Primary structure (of a protein) the order (sequence) of amino acids in the protein chain.

Probability distribution (orbital) a representation indicating the probabilities of finding an electronat various points in space.

Product a substance resulting from a chemical reaction.It is shown to the right of the arrow in a chemical equation.

Protein a natural polymer formed by condensation reactions between amino acids.

Proton a positively charged particle in an atomic nucleus.

Pure substance a substance with constant composition.

Q

No entries for this letter

R





Radioactive decay (radioactivity) the spontaneous decomposition of a nucleus to form a differentnucleus.

Radiocarbon dating (carbon-14 dating) a method for dating ancient wood or cloth on the basis ofthe radioactive decay of the nuclide 146C.

Radiotracer a radioactive nuclide, introduced into an organism for diagnostic purposes, whosepathway can be traced by monitoring its radioactivity.

Random error an error that has an equal probability of being high or low.

Rate of decay the change per unit time in the number of radioactive nuclides in a sample.

Reactant a starting substance in a chemical reaction.It appears to the left of the arrow in a chemical equation.

Reactor core the part of a nuclear reactor where the fission reaction takes place.

Reducing agent (electron donor) a reactant that donates electrons to another substance, reducingthe oxidation state of one of its atoms.

Reduction a decrease in oxidation state (a gain of electrons).

Rem a unit of radiation dosage that accounts for both the energy of the dose and its effectiveness incausing biological damage (from roentgen equivalent for man).

Resonance a condition occurring when more than one valid Lewis structure can be written for aparticular molecule.The actual electronic structure is represented not by any one of the Lewis structures but by the averageof all of them.

S

Salt an ionic compound.

Salt bridge a U-tube containing an electrolyte that connects the two compartments of a galvanic cell,allow- ing ion flow without extensive mixing of the different solutions.





Saturated solution a solution that contains as much solute as can be dissolved in that solution.

Scientific method a process of studying natural phenomena that involves making observations,forming laws and theories, and testing theories by experimentation.

Scientific notation see Exponential notation.

Scintillation counter an instrument that measures radioactive decay by sensing the flashes of lightthat the radiation produces in a detector.

Secondary structure (of a protein) the three-dimensional structure of the protein chain (forexample, a-helix, random coil, or pleated sheet).

SI units International System of units based on the metric system and on units derived from the metricsystem.

Sigma ( ) bond a covalent bond in which the electron pair is shared in an area centered on a linerunning between the atoms.

Significant figures the certain digits and the first uncertain digit of a measurement.

Silica the fundamental silicon-oxygen compound, which has the empirical formula SiO2 and forms thebasis of quartz and certain types of sand.

Silicates salts that contain metal cations and polyatomic silicon - oxygen anions that are usuallypolymeric.

Single bond a bond in which two atoms share one pair of electrons.

Solid one of the three states of matter; has a fixed shape and volume.

Solubility the amount of a substance that dissolves in a given volume of solvent or solution at a giventemperature.

Solubility product the constant for the equilibrium expression representing the dissolving of an ionicsolid in water.

Solute a substance dissolved in a solvent to form a solution.

Solution a homogeneous mixture.

Solvent the dissolving medium in a solution.





Somatic damage radioactive damage to an organism resulting in its sickness or death.

Specific heat another name for specific heat capacity.

Specific heat capacity the amount of energy required to raise the temperature of one gram of asubstance by one Celsius degree.

Spectator ions ions present in solution that do not participate directly in a reaction.

Standard atmosphere a unit of measurement for pressure equal to 760 mm Hg or 101, 325 Pa.

Standard solution a solution the concentration of which is accurately known.

Standard temperature and pressure (STP) the condition 0 C and 1 atmosphere of pressure.

State function a property that is independent of the pathway.

States of matter the three different forms in which matter can exist: solid, liquid, and gas.

Stoichiometric quantities quantities of reactants mixed in exactly the amounts that result in their allbeing used up at the same time.

Stoichiometry of a reaction the relative quantities of reactants and products involved in the reaction.

Strong acid an acid that completely dissociates (ionizes) to produce H1 ion and the conjugate base.

Strong base a metal hydroxide compound that completely dissociates into its ions in water.

Strong electrolyte a material that, when dissolved in water, dissociates (ionizes) completely and givesa solution that conducts an electric current very efficiently.

Structural formula the representation of a molecule in which the relative positions of the atoms areshown and the bonds are indicated by lines.

Subcritical reaction (nuclear) a reaction in which fewer than one of the neutrons from each fissionevent causes another fission event and the process dies out.

Sublimation the process by which a substance goes directly from the solid state to the gaseous statewithout passing through the liquid state.Substitution reaction (hydrocarbons) a reaction in which an atom, usually a halogen, replaces ahydrogen atom in a hydrocarbon.





Supercooling the process of cooling a liquid to a temperature below its freezing point without itschanging to a solid.

Supercritical reaction (nuclear) a reaction in which more than one of the neutrons from each fissionevent causes another fission event.The process rapidly escalates to a violent explosion.

Superheating the process of heating a liquid to a temperature above its boiling point without itsboiling.

Surroundings everything in the universe surrounding a thermodynamic system.

System (thermodynamic) that part of the universe on which attention is to be focused.

Systematic error an error that always occurs in the same direction.

T

Temperature measure of the random motions (average kinetic energy) of the components of asubstance.

Tertiary structure (of a protein) the overall shape of a protein, long and narrow or globular,maintained by different types of intramolecular interactions.

Theoretical yield the maximum amount of a given product that can be formed when the limitingreactant is completely consumed.

Theory (model) a set of assumptions put forth to explain some aspect of the observed behavior ofmatter.

Thermodynamics a study of energy and its interactions.

Titration a technique in which one solution is used to analyze another.

Torr another name for millimeters of mercury (mm Hg).

Trace elements metals present only in trace amounts in the human body.





Transition metals several series of elements in which inner orbitals (d or f orbitals) are being filled.

Transuranium elements the elements beyond uranium that are made artificially by particlebombardment.

Triple bond a bond in which two atoms share three pairs of electrons.

U

Uncertainty (in measurement) the characteristic reflecting the fact that any measurement involvesestimates and cannot be exactly reproduced.

Unit factor an equivalence statement between units that is used for converting from one set of units toanother.

Universal gas constant the combined proportionality constant in the ideal gas law; 0.08206 L atm/Kmol, or 8.314 J/K mol.

Unsaturated solution a solution in which more solute can be dissolved than is dissolved already.

V

Valence electrons the electrons in the outermost occupied principal quantum level of an atom.

Valence shell electron pair repulsion (VSEPR) model a model the main postulate of which is thatthe structure around a given atom in a molecule is determined principally by the tendency to minimizeelectron-pair repulsions.

Vapor pressure the pressure of the vapor over a liquid at equilibrium in a closed container.

Vaporization (evaporation) the change in state that occurs when a liquid evaporates to form a gas.

Viscosity the resistance of a liquid to flow.

Volt the unit of measurement for electric potential; it is defined as one joule of work per coulomb ofcharge transferred.





W

Wavelength the distance between two consecutive peaks or troughs in a wave.

Weak acid an acid that dissociates only to a slight extent in aqueous solution.

Weak base a base that reacts with water to produce hydroxide ions to only a slight extent in aqueoussolution.

Weak electrolyte a material that, when dissolved in water, gives a solution that conducts only a smallelectric current.

Weight the force exerted on an object by gravity.

Work force acting over a distance.

X

Y

Z



57135408 chemistry 5070 complete notes for o level (1)

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