chemistry terms 1

8/9/2019 Chemistry Terms 1

1/25

CHEMISTRYTERMS

COMPILED

ByDr.M.VENKATAPA

THY


2/25

ATOM: An atom is the smallest particle of matter consisting of a

positively charged nucleus andnegatively charged electrons.DALTONS ATOMIC MODEL:This model suggest that atoms areindivisible.J.J. THOMSONS MODEL: An atom is a solid sphere of positivelycharged particles in which electronsare embedded like seeds in watermelon fruit.RUTHERFORDS MODEL.The protons and neutrons are present in asmall dense positively chargedcore called nucleus and all the electrons revolve around the nucleus incircular paths like planetary model.

BOHRS MODEL.The protons and neutrons are present in the nucleusand all the electrons revolvearound the nucleus in definite orbits.SOMMERFIELD MODEL: According to this, the electron movingaround the nucleus must describe anelliptical orbit in addition to circular orbits as suggested by Bohr.QUANTUM MECHANICAL MODEL OF AN ATOM: According to this,electrons are considered asthree dimensional wave in electric field of the positively chargednucleus.ELECTRON: It is a negatively charged particle which occupies the

space outside the nucleus in an atom.PROTON: It is a positively charged particles present in the nucleus ofan atom.NEUTRON: It is a neutral particle of mass equal to the mass of proton.ORBIT: It is a definite circular path in which the electron is supposedto revolve around the nucleus.ORBITAL: It is the three dimensional region around the nucleus inwhich the probability of finding theelectron is maximum.ELECTRONIC CONFIGURATION: Distribution of electron in differentorbitals of the atom of an

element.s-ORBITAL: s orbital is spherically symmetric around the nucleus.p-OTBITAL: p orbital is dumb-bell shaped and consists of two lobes ofelectron cloud.PRINCIPAL QUANTUM NUMBER (n): It describes the energy of theenergy level in which theelectron revolving around the nucleus. It also describes the distancebetween the nucleus and the electron.


3/25

AZIMUTHAL OR ORBITAL QUANTUM NUMBER (l): It represents thesub energy level which ispresent in main energy level.MAGNETIC QUANTUM NUMBER (m): It gives how many orientationsare possible for a sub energy

level in space, when an electron present in a sub shell.SPIN QUANTUM NUMBER (s): It describes the direction of the spin ofthe electron (either clock wiseor anticlock wise).HUNDS RULE: Among the orbitals of same energy, electrons do notstart pairing, until all these orbitalsare singly occupied. Hunds rule is also called as the principle ofminimum pairing and the principle ofmaximum multiplicity.AUFBAUS PRINCIPLE: Electrons are filled in the increasing order ofenergy level According to this

principle first the electrons occupy the orbitals with lowest energy. Thisis decided by the sum of theprinciple quantum number and azimuthal quantum number. This iscalled (n + l) rule.PAULI PRINCIPLE: In an atom no two electrons can have the same set offour quantum numbers.

OXIDATION: Removal of one or more electron from an atom ormolecule or ion is called oxidationREDUCTION: Addition of one or more electrons to an atom ormolecule or ion is called reduction.REDUCING AGENT: A substance which gives one or more electrons to

the other is called a reducingagent.OXIDISING AGENT: A substance which accepts one or more electronsfrom the other is called anoxidizing agent.Avogadro number (N): It is defined as the number of atoms present inexactly 12 grams of 6C12 isotope. It isdenoted by N. It has a value of 6.023 1023.Atomicity.The number of atoms contained in one molecule of the elementis called its atomicity.Avogadros hypothesis. Equal volumes of all gases at the sametemperature and pressure contain the same

number of molecules.Vapour density. Vapour Density is defined as the ratio of the mass of acertain volume of the gas or vapour tothe mass of the same volume of hydrogen at the same temperature andpressure.Atomic weight.The relative atomic mass of an element is the mass of oneatom of the element compared withthe mass of one atom of hydrogen taken as one unit.


4/25

Gram atomic weight of an atom.The atomic weight of an elementexpressed in grams is known as the gramatomic weight (or gram atom) of the element.For example, Gram atomic weight of carbon = 12 gGram atomic weight of oxygen = 16 g.Molecular mass.The relative molecular mass of an element or a compound

is the mass of one molecule of theelement or compound compared with the mass of one atom of hydrogentaken as one unit.Mole concept.Definition 1:The mole is the amount of substance, which contains as manyparticles (atoms, molecules, ions,etc.) as there are carbon atoms in 12 grams of the 6C12 isotope.Definition 2: A mole is defined as the amount of substance which containsAvogadro number (6.023x1023) ofparticles.Gram molecular weight.The molecular weight of a substance expressed ingrams is known as gram molecular

weight of the substance. The gram molecular weight of oxygen is 32g andthat of sulphuric acid is 98g.Molar volume. Volume occupied by one mole of any gas is called molarvolume or gram molecular volume. Itis 22.4L (or) 2.24 10-2 m3at S.T.P. It contains 6.023 1023 molecules.Equivalent mass of an element. Equivalent mass of an element is definedas the number of parts by mass ofthat element which can displace or combine with 1.008 parts by mass ofhydrogen or 8 parts by mass of oxygenor 35.46 parts by mass of chlorine or one equivalent mass of any otherelement. It is only a relative number andhence it does not have any units. When equivalent mass is expressed ingram, it is called gram equivalent mass.Equivalent mass of an acid. Equivalent mass of an acid is the number ofparts by mass of the acids whichcontains 1.008 parts by mass of replaceable hydrogen.Basicity: Basicity of mineral acid is defined as the number of Replaceablehydrogen atoms present in one moleof the acid. Basicity of organic acid is defined as the number of carboxylicgroups present in the acid.Equivalent weight of base. Equivalent mass of the base is the number ofparts by mass of the base required toneutralize one equivalent mass of an acid.Acidity of a base. Acidity of hydroxide base is defined as the number ofreplaceable hydroxyl ions present inone mole of the base.Equivalent mass of salt. Equivalent mass of a salt is the number of partsby mass of salt which reacts with oneequivalent of mass of any other substance.Equivalent weight of an oxidising agent. Equivalent weight of oxidizingagent is the number of parts by mass


5/25

of it, which contains 8 parts by mass of available oxygen. Available oxygenmeans, oxygen capable of beingutilised for oxidation.Equivalent mass of a reducing agent. Equivalent weight of reducingagent is the number of parts by mass of it,which can be oxidized by 8 parts by mass of oxygen.

Normality of a solution. Normal solution is a solution, which contains onegram equivalent mass of thesubstance dissolved in one litre of the solution.Law of volumetric analysis: When two solutions completely react witheach other, the product of volume andnormality of one solution will be equal to the product of volume and normalityof the other solution.Standard solution. In a titration, concentration of either the solution in theburette or in the conical flask shouldbe exactly known. The solution whose concentration is exactly known iscalled the standard solution. A standardsolution can be prepared by dissolving a known mass of the substance in a

known volume of the solution.

Law of mass action: The total mass of substances taking part in achemical reaction remains the samethroughout the change.Law of multiple proportion: When two elements A and B combine to formtwo or more compounds, thendifferent weights of B which combine with a fixed weight of A bears a simplenumerical ratio to one another.Law of conservation of mass: When two elements combine separatelywith a definite mass of a third element,then the ratio of their masses in which they do so is either the same or somewhole number multiple of the ratioin which they combine with each other.Limitations of Law multiple proportion:The law is valid till an element ispresent in one particular isotopicform in all its compounds. When an element exists in the form of differentisotopes in its compounds, the lawdoes not hold good.Stoichiometry a branch of chemistry in which quantitative relationshipbetween masses of reactants andproducts are established. The study of these laws led to the development of atheory concerning the nature ofmatter.

Instantaneous (or) fast reactions:These reaction occur at once, forexample, ionic reactions such as acid-base

neutralization reaction and precipitation reaction NaOH + HCl NaCl + H2OReactions of this type proceed so quickly and their rates cannot bedetermined by common methods.Rate of reaction: Rate or velocity of a chemical reaction is defined aschange in molar concentration of one of


6/25

the reactants or products in unit time.dxChange in molar concentration

Rate = ---- = -------------------------------------dtTimedxmol / dm3

Unit: Rate = ---- = -------------

dtsecondRate of the reaction is expressed in mol /dm3 /s or mol dm3 s1.Law of mass action: At constant temperature, the rate of a chemicalreaction is directly proportional to theproduct of active masses of the reactants.

No of molesAtomic mass = -------------------------------------

Volume of the containing vesselPhotochemical reaction: A few chemical reactions take place only whenthe reacting substances after mixing isexposed to light.

Chemical equilibrium: When the rate of forward reaction becomes equal tothe rate of backward reaction. Thisstate is called chemical equilibrium.Thermo chemistry is a branch of chemistry which deals with the study ofheat change during various physicaland chemical transformations.Endothermic reaction: A reaction which takes place with the absorption ofheat is called endothermic reaction.

For an endothermic reaction, Hp > HR. Hence H = +ve.Active mass means effective molar concentration and in a dilutesolution, it can be considered to be

equal to molar concentration expressed in mol/dm3 or partial pressureexpressed in (N/m2) in the caseof gases.Exothermic reaction: A reaction which takes place with the evolution ofheat is known as exothermic reaction.

For an exothermic reaction, Hp < HR. Hence, H = ve. eg. (i) C(s) + O2(g) CO2

(g); H = 393.5 kJReasons for difference in rates: A chemical reaction involves the breakingand making of bonds. A strongbond requires more energy to break, than a weak bond. A reaction whichinvolves breaking of strong bonds, will

be slow or impossible to occur at room temperature. On the other hand, areaction which involves breaking ofonly weak bonds will be fast under similar conditions.Irreversible reaction: A reaction in which the products formed do notrecombine to produce the originalreactants is called an irreversible reaction.Reactions involving liberation of a gas or those in which a precipitate isformed are generally irreversible


7/25

reactions. eg.: Zn + H2SO4 ZnSO4 + H2 Conditions for reversible reaction: 1. The reaction should be done in aclosed vessel. 2.None of the productsshould be removed from the vessel. 3. Temperature and pressure should bekept constant.Reversible reaction: A reaction in which the products formed react to give

back the original substances iscalled a reversible reaction. Example: N2 + 3H2 2NH3 .In a reversible reaction,the reaction proceedingfrom left to right is called a forward reaction. The reaction proceeding fromright to left is called a backwardreaction or reverse reaction.Factors influencing the rate of a reaction: 1. Concentration of thereactants 2. Temperature: 3. Presence of aCatalyst 4. Nature of reactants 5. Nature of the solvent 6. Exposure toradiations 7. Surface areaClassification of the reactions:(a) Instantaneous (or) fast reactions:These reaction occur at once, forexample, ionic reactions such as acidbaseneutralization reaction and precipitation reaction NaOH + HCl NaCl + H2OReactions of this type proceed so quickly and their rates cannot bedetermined by common methods.(b) Extremely slow reactions: Some reactions proceed at extremely slowrates. For example, rusting of iron,combination of hydrogen and oxygen at room temperature etc., are few suchreactions, which takes months, oreven years before any observable change occur.(c) Reactions with moderate speeds: In between the two extremesdiscussed above, there are a large number ofreactions, which proceeds at moderate rates. A few examples of this type aregiven below.

(i) Decomposition of hydrogen peroxide 2H2O2 (liq) 2H2O(liq) + O2(g)

Metallic lustre: The property of metals due to which they shine iscalled metallic lustre. Thebright lustre of metals is due to their ability to reflect the incident lightfrom their face and thesurface acquires a shining appearance, which is known as metalliclustre.2. Metals are solids: Most of the metals are generally solids at room

temperature except mercury,which is liquid at room temperature.3. Metals are hard: Due to strong forces of attraction between themetal atoms, they are generallyhard except sodium and potassium which are soft metals .Thehardness varies from metal to metal.The metals like magnesium (Mg), lead (Pb), aluminium (Al), Iron (Fe),copper (Cu), etc. cannot be


8/25

cut with a knife, so these are not soft metals.4. Metals are malleable and ductile: Metals can be beaten intosheets (malleability) and drawn intowires (ductility).5. Thermal conductivity: Metals are good conductors of heat. For

example iron, silver, gold,aluminium , etc. conduct heat.6. Electrical conductivity: Metals are good conductors of electricity.7. Sonorous: Most of the metals produce ringing sound when they arestruck.8. Tensile strength: Metals resist breaking when stretched. This is ameasure of their tensile strength.Metals like tungsten have very high tensile strength.9. Density: Metals generally have high densities, e.g., density of gold,mercury and iron is 19.3,13.6 and 7.6 g/cc. respectively.

Minerals:The various compounds of metals, which occur in natureand are obtained by mining, arecalled minerals.Ores:These are minerals from which metals can be conveniently andeconomically extracted.Matrix or gangue:The unwanted impurities such as mud, stones,sand etc. which are present in theore are called matrix or gangue.Metallurgy:The process of extraction of pure metals from their oresis called metallurgy. The methodof extraction of metal depends on the nature of the metal and the

nature of its ore.Refining of metals:The process of purification of impure metals byremoving metallic andnonmetallic impurities is known as refining of metals.Poling:The impure metal is melted and the molten metal is stirredwith logs of green wood. Theimpurities are removed either as gases or they get oxidised formingscum over the molten metalLiquation:This method is used for refining those metals, which havelow melting point such as tin,lead etc., The impure metal is placed on the sloping hearth of a

furnace and gently heated. The metalmelts and drain away leaving behind the infusible materials on thehearth.Distillation:This process is employed for purification of volatilemetals like mercury, zinc andcadmium. The impure metal is heated in a retort and its vapours areseparately condensed in a receiver.


9/25

While the pure metal distills over, the non-volatile impurities are leftbehind in the retort.Zone refining: Ultra pure metals and non-metals are obtained byzone refining process. It is alsocalled fractional crystallisation method because this refining is based

on the principle that when animpure metal is melted and allowed to solidify, the impurities moveaway from the solid region andprefer to be distributed in the molten region.Electrolytic refining:This method is most widely used for refiningimpure metals. Metals such ascopper, zinc, tin, nickel etc., are refined electrolytically.Oxidation:This method is generally employed in the purification ofmetals, when the impurities getoxidised more readily than the metal itself.

The important minerals of aluminium are: 1.Bauxite (Al2O3. 2H2O )2.Cryolite (Na3AlF6 )3. Corundum (Al2O3 )The extraction of aluminium requires three stages:(a) Purification of bauxite (b) Electrolytic reduction (c) Refining ofaluminiumAluminium is a self-protecting metal because the oxide film onaluminium protects it from furtherattack of air.The minerals of copper are:1. Copper pyrites (CuFeS2 ) 2. Copper glance ( Cu2S.) 3. Cuprite (Cu2O.)

4. Malachite (Cu(OH)2 . CuCO3.) 5. Azurite ( 2CuCO3 . Cu(OH)2.)Concentration of Ore: Copper pyrites being a sulphide ore, isconcentrated (dressed or enriched) bythe froth- floatation process.Roasting:The concentrated copper pyrites ore is roasted in air in ablast furnace.Conversion to Metal: When a good amount of copper sulphide hasbeen converted into copper oxide,then after some time, the supply of air for roasting is stopped. In theabsence of air, Copper oxideformed above reacts with the remaining copper sulphide to form

copper metal:Bessemerization:The Process in which copper oxide reacts withcopper sulphide to form coppermetal is called bessemerization.Electrolytic refining: Impure copper metal is refined by electrolysismethod called electrolyticrefining.


10/25

The minerals of iron are: 1.Haematite( Fe2O3 ) 2.Magnetite (Fe3O4 )3.Siderite(FeCO3 )4.Limonite( 2Fe2O3. 3H2O )Concentration (levigation):The powdered ore is washed with astream of water whereby the lighter

sand particles and other impurities are washed away and the heavierore particles settle down.Calcination:The Concentrated ore is strongly heated in a limitedsupply of air in a reverberatoryfurnace. During roasting (a) moisture is driven out and (b) impuritieslike sulphur, arsenic, phosphorusetc are oxidised off.Smelting:The roasted ore is mixed with limestone and coke andheated in a blast furnace in order toreduce the iron oxide to the metal.Tuyers:These are small pipes (tuyers) through which a blast of hot air

is admitted and a slagholethrough which slag can be withdrawn.Types of zones:The various types of temperature zones are (a)combustion zone (b) fusion zone(c) slag formation zone (d) reduction zoneThree commercial forms of iron: (a) Cast iron (b) Wrought ironand (c) steel.Cast iron: It is the most impure form of iron containing 2-4.5% ofcarbon. It is very hard and brittle.Wrought iron: It is the purest form of iron obtained by the removal ofcarbon almost completely. It

contains less than 0.25% carbon.Steel: Steel is an alloy of iron with 0.25% to 2% carbon. Thepercentage of carbon in steel isintermediate between that in wrought iron and in cast iron.Different types of steel: Based on carbon content, there are threetypes of steel.Mild steel: It has the least carbon content; 0.1 to 0.15%. It is used formaking wires and sheets.Medium steel: It contains 0.2 to 0.5% carbon. It is harder than mildsteel and is used for constructingrails, wheels etc.

Hard steel:This type of steel contains 0.5 to 1.5% carbon. It is veryhard and used for makingmachine parts.Special steels or alloy steels: Steel mixed with small amount ofnickel, cobalt, chromium, tungsten,molybdenum, manganese, etc., acquires special properties. Suchproducts are called special steels oralloy steels. Some important alloy steels are described.


11/25

Corrosion: It may be defined as the slow and steady destruction of ametal or alloy by the environment.In case of iron, corrosion is called rusting. Rust is a hydratedferric oxide represented asFe2O3.H2O.

Methods Of Preventing CorrosionCoating with paints: Metal surfaces coated with paint which keep itout of contact with air, moisture,etc., till the paint layer develops cracks.Coating with oils and greases: By applying film of oil and grease onthe surface of the iron tools andmachinery, the rusting of iron can be prevented since it keeps themetal surface away from moisture,oxygen and carbon dioxide.Alloying: Some metals, when mixed with other metals, becomeresistant to corrosion. Stainless steel

is an alloy of iron, which does not undergo corrosion easily.Galvanisation:This process involves the coating of zinc on ironsheets to prevent rusting. Galvanisediron is used to make buckets, boxes, utensiles etc., and othercommonly used articles.Tinning:This process involves the coating of tin (with molten tin) oncooking vessels made of copperand brass.Anodizing: In this process metals like aluminium, copper, etc. arecoated electrically with a thin andstrong film of their oxides which protects them from rusting. Articles

such as soap cases, handles,doorknobs, etc., are commonly anodized aluminium articles.Electroplating: It is a process of depositing stable metal (gold, silver)over a base metal (copper, iron)Iron can be coated with copper by electro deposition from a solution ofcopper sulphate.

Non-Metals: Non metals are the elements which form negative ionsby gaining electrons. Hydrogen,oxygen, carbon, Sulphur, silicon and phosphorus are some of thecommon non metals.

Inert Gases: Helium, neon, argon, krypton, xenon and radon are theinert gases which are also non metals.Position in the periodic table:The most metallic elements are onthe extreme left side of the periodictable whereas non metallic elements are on the extreme right side inthe periodic table.


12/25

Electronic configuration: Non metals have usually 4 to 8 electronsin the outermost shells of theiratoms.Physical Properties of Non MetalsNature: Non metals are brittle and bas conductor of heat and

electricity (except graphite).Melting and Boiling points: Non metals have low melting andboiling points except graphite anddiamond.Silicon: It is the second most abundant element occurring in theearths crust; the first being oxygen.Silica:The simplest compound of silicon and oxygen is silicon dioxide.Types of silica: Sand, quartz and opal.Ferrosilicon: It is an alloy of silicon. It is used in the manufacture ofapparatus for redistilling nitricacid.

Silico Bronze: It is used in the manufacture of telegraph andtelephone wires.Sodium Silicate: It is used for preserving eggs and for makingchemical garden.Silicones:They are polymeric organo silicon compounds having C Siand Si O Si bonds.Position in the periodic table: Silicon is an element of group IV (14in modern periodic table) andoccurs below the carbon in the periodic table.PhosphorusElectronic configuration:The electronic configuration of phosphorus

is 1s2, 2s2, 2p6, 3s2, 3p3.Position in the periodic table: Phosphorus is placed in group V ofthe periodic table below nitrogen.Allotropic forms of phosphorus: White P, red P, scarlet p, metallicblack P, violet P.Phosphorescence:The property of glowing of white phosphorous inthe dark.Allotropy: Allotropy is a phenomenon in which the same element canexist in more than onecrystalline or structural modification with change in physicalproperties.

SulphurElectronic configuration:The electronic configuration of Sulphur is1s2, 2s2, 2p6, 3s2, 3p4.Position in the periodic table: Sulphur is placed in-group VI (16 inmodern periodic table) belowoxygen.Allotropes of Sulphur: (i) Rhombic Sulphur, (ii) Monoclinic orPrismatic Sulphur, (iii) Plastic or


13/25

Amorphous Sulphur.

Alcohols: Alcohols are organic compounds with general formula R OH where R is an alkyl group.Hydroxy derivatives: Alcohols may be considered as hydroxy

derivatives of hydrocarbons in whichone or more hydrogen atoms are replaced by hydroxyl (-OH) group.Aliphatic alcohols:The open chain alcohols are called aliphaticalcohols where R is an alkyl group.Classification: Alcohols are classified as mono, di, tri and polyhydricalcohols.Nomenclature:There are two methods for naming alcohols. (a)Common Name (b) IUPAC nameFermentation: It is a slow anaerobic decomposition of big organicmolecules into simpler ones underthe catalytic influence of non-living complex substances called

ferments. In many causes enzymes actsas ferments.Molasses: It is the mother liquor left over after the crystallization ofsugar from the sugarcane juice. Itis a dark colored syrupy liquid containing 50 55 % total sugars (suchas sucrose, glucose andfructose).Wash:The filtrate collected in fermentation contains almost 10% ofethyl alcohol, called wash.Azeotropic mixture: It is a mixture, which boils at a constanttemperature and distills over completely

at the same temperature without change in composition.Denatured alcohol: Rectified spirit is made unfit for drinkingpurpose, by adding 5% methyl alcohol(poison), 0.5% pyridine (unpleasant odour) and some colouring matter(methyl violet dye). It is calleddenatured alcohol or methylated spirit.Power alcohol: Rectified spirit does not mix properly with petrol.Hence, it is mixed with ether orbenzene. One part of this mixture is added to four parts of petrol. Thisis called power alcohol orgasohol.

Esterification: The process of the formation of an ester (ethylethanoate) by the combination of ethanolwith ethanoic acid is known as esterification.Detection of Alcohol: Alcohol can be detected by the following tests.Sodium metal test: when a small piece of sodium is added to analcohol, hydrogen gas is evolvedwith effervescence.


14/25

Phosphorous pentachloride test: On treatment with phosphorouspentachloride, alcohols becomewarm and hydrogen chloride gas is evolved.

Ethers:They are organic compounds with the general formula (R-O-R1)

where R and R1

are alkyl or arylgroups. The groups R and R1 may be either the same or different.

Types of Ethers: There are two types of ethers:(i) Simple ethersor symmetrical ethers, (ii) Mixedethers or unsymmetrical ethers. If Rand R1 are the same the ethers arecalled simple ethers. and if Rand R1 are different these are called mixed ethers.Nomenclature: (a) Common name (b) IUPAC name(a) Common system: In the Common system the ethers are namedaccording to the alkyl groupbonded to the oxygen atoms. The two-alkyl groups bonded to the

functional group(-O-) are written alphabetically followed by the word ether Forexample CH3 - O - C2H5i.e. Ethyl methyl ether ( arranged alphabetically)If both the groups are similar prefix like di is attached.For example CH3 - O - CH3 i.e Dimethyl ether

(b) IUPAC System: In IUPAC System, the ethers are named as alkoxyalkanes. The oxygen atom istakes with the smaller alkyl group while the larger alkyl group formsthe parent chain1 2 3

For example CH3 - O - C2H5 CH3 - O - CH2-CH2-CH3i.e.1- Methoxy ethane i.e. Methoxy propaneWilliamsons ether synthesis: When an alkyl halide is heated withsodium or potassium alkoxide, anether is obtained. Both symmetrical and unsymmetrical ethers can beprepared by this method.1. Physical state: Dimethyl ether and ethyl methyl ether are gases atroom temperatures. Other lowermembers are colourless liquids, which are highly volatile.2. Boiling points: Ethers have much lower boiling points compared toisomeric alcohols as they are

not associated with hydrogen bonds. Their boiling points arecomparable to the correspondingalkanes.3.Volatility and flammability: Due to low boiling points, the lowermembers are highly volatile andthus catch fire immediately. So lower ethers are highly inflammable.4.Solubility: Ethers are soluble in hydrocarbons and other non-polarsolvents. Ethers are generally


15/25

insoluble in water, but their solubility in water is not negligible.5. Inertness: Owing to the absence of active groups and multiplebonds, ethers are comparatively inertsubstances. They are not easily attacked by alkalies, dilute acids, PCl5.metallic sodium etc.

They undergo chemical reactions under specific conditions. Some ofthe reactions of ethers aredue to:

Carbonyl Compounds: Organic compounds containing carbonyl ( C =O) group are known ascarbonyl compounds.Nomenclature of AldehydesCommon system: Aldehydes are named after the carboxylic acidsthey form on oxidation. The nameis obtained by replacing the terminal ic acid in the name of the acid

by the suffix aldehyde.IUPAC system:The ending of the name (suffix) of aldehyde is al.The names of aliphatic aldehydesare derived from the name of the corresponding alkane by replacingthe terminal e by the suffix al.Name of aldehyde = Name of corresponding alkane -e + al.Nomenclature of KetonesCommon system:The names of ketones are obtained by naming thetwo alkyl groups attached to theketo group (alphabetically) and adding the suffix ketoneIUPAC system:The characteristic ending for ketones is -one. The

names of individual aliphaticketones are derived by replacing the terminal e in the name of thecorresponding alkane by the suffix-one.Carboxylic acids: Organic compounds which contain the carboxylfunctional group (-COOH) arecalled the carboxylic acids. Their general formula is R - C -OH orR -COOH where R is an alkyl

group. | |OFatty acids:The long chain monocarboxylic acids are commonly

called Fatty acids because many ofthem are obtained by the hydrolysis of animal fats or vegetable oils.Eg. Stearic acid, Palmitic acid.Nomenclature of Monocarboxylic AcidsCommon system:The common names are usually derived from theLatin or Greek word that indicatesthe original source of the acid. For example: Formic acid is present inants (Latin formica = ants) and


16/25

acetic acid is present in vinegar (acetum = vinegar).IUPAC System:The names of the carboxylic acids are derived fromthe names of the parenthydrocarbons by replacing the terminal e by oic acid.Test For Carboxylic acid: 1. When ethanoic acid (acetic acid) is

warmed with ethanol in the presenceof a few drops of concentrated sulphuric acid, a sweet smelling estercalled ethyl ethanoate is formed.2. Acetic acid produces red colour when a neutral solution of ferricchloride is added to it.Glacial acetic acid: Acetic acid, when cooled sufficiently it forms icelike crystals which melts at16.7oC. Hence the pure anhydrous acid is usually called glacial aceticacid.Soda lime: It is a mixture of caustic soda (NaOH) and quick lime(CaO).

Decarboxylation:The removal of carbon dioxide from a carboxylicacid is known as decarboxylation.Vinegar: Dilute aqueous solution (5 8%) of ethanoic acid is calledvinegar, which is used to preservefoodQuick vinegar process: Vinegar is prepared by the fermentation ofethyl alcohol with the bacteriaacetobacter in the presence of air.Pyroligneous acid: It is a mixture containing 10% acetic acid, 4%methyl alcohol and 0.5% acetone.

Pollution: It is defined as an addition or excessive addition ofundesirable materials to the physicalenvironment (air, water, and land), making it less fit or unfit for life.Basic Cause of Pollution: -There are two main causes of pollution(1) Human activities and (2) Natural phenomena.Pollutant: A substance released into the environment due to naturalor human activity and effectadversely the environment is called as pollutant, eg : sulphur dioxide,carbon monoxide, lead, mercuryetc.Receptor:The medium which is effected by the pollutant is called

receptor.Eg: When many vehicles stop at the traffic signal during peak hours,our eyes become red with burningsensation due to the smoke released from the automobiles. The eyeshere are the receptors.Sink:The medium which reacts with pollutants is called sink. Eg:Micro-organisms which eat the dead


17/25

animals or which convert the dried leaves and garbage into fertilizers.Thus, the pollutant is removedby micro -organisms. Similarly, seawater is a big sink for carbondioxide.

Classification

Quantitative pollutantsThese are the substances, which normally occur in nature but are alsoadded in large qualities byman. For instance: carbon dioxide. It is always present in the air, and isalso released by fires,industries and automobiles.Qualitative pollutantsThese are the substances which do not occur in nature but are addedby man. The insecticides andherbicides, for example, are qualitative pollutants.Biodegradable pollutants

These are quickly degraded by natural means. Sewage and heat arepollutants of this category.These pollutants are disposed of by microbial action and radiation.Non degradable pollutantsThese are not degraded or are degraded very slowly in nature. D.D.T.,arsenic salts of heavymetals, glass or tin containers, radioactive materials, and plastic arethe pollutants of this category.These pollutants accumulate and may get biologically magnified asthey pass through the food chains.Primary pollutants

These persist in the form in which they added to the environment.Plastic ware are primarypollutants.Secondary pollutantsThese are formed by interaction among the primary pollutants. Forexample, two primarypollutants, namely, nitrogen oxides and hydrocarbons, from motorvehicles, react in the presence ofsunlight to form two secondary pollutants, viz., peroxyacyl nitrate(PAN) and ozone. These are moretoxic than the primary pollutants. This phenomenon of increased

toxicity by reaction among thepollutants is called synergism.Types of pollution: (i) Air pollution (ii) Water pollution. (iii) Soil orland pollutionAir pollution: It refers to the release into the atmosphere, ofmaterials that are harmful to man, otheranimals, plants and buildings or other objects.


18/25

Causes of air pollution:There are two main causes of air pollution:human activities and naturalphenomena.(a) Human ActivitiesWater Pollution: It is defined as the addition of some foreign

substance (organic, inorganic, biologicalor radiological) to water, or change in its physical property (heat) thatconstitutes a health hazard orotherwise make it less fit or unfit for use.Soil Pollution: Alteration in soil by addition and removal of materialsleading to reduce productivity iscalled soil pollution.Soil Pollutant: Substances which reduce productivity of the soil areregarded soil pollutants.Type of soil pollution: Soil Pollution is of two main types: Positiveand negative.

Green chemistry: It is defined as the design of chemical products andprocesses that reduce oreliminate the use and generation of hazardous substances. Theultimate aim of green chemistry orenvironment friendly chemistry is to prevent pollution at the source.

P,V,T and mass are the measurable properties of gas. They obeyBoyle's and Charle's law. The equation of state for an ideal gas in PV =

nRT.

Different units of R :0.0821 it atm K-1mol-1;8.314 x 107 erg K-1 mol-1;

8.314 joule K-1 mol-1;1.987 cal K-1 mol-1.

Equation of state of gaseous mixture is PV = (nA + nB + nC) RT. By Graham's law, (diffusion rate1/diffusion rate2) = (M2/M1) (or)(effusion rate1/ effusion rate2) = (M2/M1)

Real gases deviate from Videal and Pideal. The equation of state of real gas= Vanderwaal equation

aP + __ (V-b) = RT for n = 1.

V2 Critical temperature, critical pressure, critical volume represent thecritical state of the gas. Andrew's isotherm describes critical

temperature of carbondioxide. Thomson's experiment describescontinuity of state.

Pc, Vc, Tc are related to Vanderwaal's constants a and b as Vc = 3b;a 8a

Pc = ____; Tc = ____27b2 27Rb

Joule Thomson effect predicts adiabatic expansion of a compressed gasthrough an orifice to cause a fall in temperature. Inversion temperature


19/25

= 2a/Rb is the temperature below which Joule Thomson effect isobeyed.

Liquefaction of gases is carried out by Linde's and Claude's processesadopting Joule-Thomson effect. Liquefaction of Helium and zerokelvin are achieved by adopting adiabatic demagnetisation.

Solids form an important part of the world around us, providing

materials with a definite shape and predictable properties.

Crystalline solids are made of ordered arrays of atoms, ions ormolecules.

Amorphous solids have no long-range ordering in their structures.The unit cell is the basic repeating unit of the arrangement of atoms,

ions or molecules in a crystalline solid.

Lattice refers to the three dimensional array of particles in a

crystalline solid. Each particle occupies a lattice point in the array.A simple cubic unit cell has lattice points only at the eight corners of

a cube.A body-centred cubic unit cell has lattice points at the eight corners

of a cube and at the centre of the cube.A face-centred cubic unit cell has the same kind of particles (lattice

paints) at the eight corners of a cube and at the centre of each face.

The geometry of the crystal may be completely defined with the help

of coordinate axes meeting at a point.The miller indices of a face of a crystal are inversely proportional to

the intercepts of that face on the various axes.The study of crystal is known as crystallography.

Groups 13 to 18 of the periodic table are known as p-block elements.

The lower oxidation states of these elements are stabilised by inert pair

effect.Group 13 is known as Boron group. The element boron is extracted

from its ore borax and colemanite. It reacts to give many compounds. Mostimportant of them is borax, which is used to identify the metallic radicals in

the qualitative analysis.

Group 14 is known as carbon group. Carbon exists in different

allotropic forms such as diamond, graphite, fullerenes and other amorphousform. The elements of this group form various hydrides, oxides, halides and

carbides.Group 15 is known as nitrogen group. The element nitrogen is essential

for plant life. It plays a vital role in fixation of nitrogen and the importancecan be studied by the nitrogen cycle.

Nitric acid is the important oxyacid of nitrogen. It is prepared byOstwald process. It oxidises metals, non-metals, compounds, etc.

Group 16 is known as oxygen group. Oxygen is the essential elementfor life. Dioxygen or molecular oxygen plays an important role in

functioning of haemoglobin and myoglobin. The study about ozone and thedepletion of ozone layer in the upper atmosphere is very essential. The

causes of ozone depletion must be considered seriously and steps should be

taken to stop the depletion.


20/25

Hydrogen is the first element in the periodic table. It exists in 3isotopes. Protium, deuterium and tritium. The preparation properties of

deuterium are dealt in detail.

Depending on the spins of the nucleus of hydrogen atom in a molecule,

two types ortho and para hydrogen are known. It can be converted from oneto another form.

One of the important compound of deuterium is heavy water, which isisolated from ordinary water. It reacts with metals, metallic oxides, acid

anhydrides etc. It also undergo exchange reaction.In 1813, L.J. Thenard prepared hydrogen peroxide by the action of

dilute acid on barium peroxide. Traces of it are found in atmosphere. Pure

H2O2 is unstable. It acts as a powerful oxidizing agent.

The use of liquid hydrogen as a fuel is explained in this chapter.Group 1 elements are known as alkalimetals. There is mostly regular

gradation in properties like density, atomic volume, melting and boilingpoint, ionization energy etc. along the group.

The extraction of lithium and sodium and its properties are explained indetail.

The model of the nuclear atom developed by Thomson, Rutherfordand their defects are explained.

Niel's Bohr model and sommerfield's extension were mentioned withdiagrammatic representation.

The location of electron in an atom through four quantum numbersare explained including their significance.

Occupancy of electrons following Hund's rule Aufbau principle,Pauli's exclusion principle are explained with represnetation.

Chemical bonding is defined and Kossel-Lewis approach to understandchemical bonding by using the octet rule is studied. Except helium,

atoms share or transfer valence electrons to attain the stable octet shell

as the electronic configuration.

Ionic bonding results due to complete electron transfer fromelectropositive elements to electronegative elements forming cation andanion. Electrostatic force of attraction between ions describe the ionic

bonding. Mutual sharing of electrons between the two atoms result incovalent bonding. The directional character, partial ionic character by

the pure orbital overlaps are also studied with suitable examples.

The geometry of simple molecules are predicted using the postulates ofVSEPR model BeCl2 : linear; CH4 : Tetrahedral; BCl3 : trigonal; PCl5 :

trigonal bipyramidal; SF6 : Octahedral. The concept of hybridisation of C, N, O are learnt. and bonds arestudied and differentiated. Resonance in benzene, carbonate ion,molecules are understood.

Formation of coordinate covalent (dative) bonding between Lewis acidsand electron donors are studied. Al2 Cl6 is covalent but in water, it is

ionic. Coordinate-covalent bonding in Ni(CO)4 is also understood.


21/25

System

Thermodynamically a system is defined as any portion of matter under

consideration which is separated from the rest of the universe by real orimaginary boundaries.

Surroundings

Everything in the universe that is not the part of system and can interact

with it is called as surroundings.Boundary

Anything (fixed or moving) which separates the system from itssurroundings is called boundary.

For example, if the reaction between A and B substances are studied,

the mixture A and B, forms the system. All the rest, that includes beaker, its

walls, air, room etc. form the surroundings. The boundaries may beconsidered as part of the system or surroundings depending upon

convenience. The surroundings can affect the system by the exchange ofmatter or energy across the boundaries.

Types of systems

In thermodynamics different types of systems are considered, whichdepends on the different kinds of interactions between the system and

surroundings.

Isolated system

A system which can exchange neither energy nor matter with its

surroundings is called an isolated system. For example, a sample in a sealedthermos flask with walls made of insulating materials represents an isolated

Closed system

A system which permits the exchange of energy but not mass, across

the boundary with its surroundings is called a closed system.For example: A liquid in equilibrium with its vapours in a sealed tube

represents a closed system since the sealed container may be heated orcooled to add or remove energy from its contents while no matter (liquid or

vapour) can be added or removed.

Open system

A system is said to be open if it can exchange both energy and matter

with its surroundings.

For eg. a open beaker containing an aqueous salt solution representsopen system. Here, matter and heat can be added or removed

simultaneously or separately from the system to its surroundings.All living things (or systems) are open systems because they

continuously exchange matter and energy with the surroundings.

(a) isolated (thermos flask)(b) closed (closed beaker)

(c) open (open beaker) systems

Homogeneous and Heterogeneous systems

A system is said to be homogeneous if the physical states of all itsmatter are uniform. For eg. mixture of gases, completely miscible mixture

of liquids etc.

A system is said to be heterogeneous, if its contents does not possess


22/25

the same physical state. For eg: immiscible liquids, solid in contact with animmiscible liquid, solid in contact with a gas, etc.

Macroscopic properties of system

The properties which are associated with bulk or macroscopic state of

the system such as pressure, volume, temperature, concentration, density,

viscosity, surface tension, refractive index, colour, etc. are called as

macroscopic properties.Types of macroscopic properties of system

Measurable properties of a system can be divided into two types.

Extensive properties

The properties that depend on the mass orsize of the system are called

as extensive properties. Examples: volume, number of moles, mass, energy,

internal energy etc. The value of the extensive property is equal to the sumof extensive properties of smaller parts into which the system is divided.

Suppose x1 ml, x2 ml,x3 ml of 1,2,3 gases are mixed in a system, the totalvolume of the system equals to (x1 + x2 + x3) ml. Thus volume is an

extensive property.

Intensive propertiesThe properties that are independent of the mass or size of the system are

known as intensive properties. For eg. refractive index, surface tension,

density, temperature, boiling point, freezing point, etc., of the system.These properties do not depend on the number of moles of the substance in

the system.If any extensive property is expressed per mole or per gram or per ml, it

becomes an intensive property. For eg: mass, volume, heat capacity are

extensive properties while density, specific volume, specific heat are

intensive properties._6812.2.1 State functions

State of a system

A system is said to be in a particular physical state when specific values

of the macroscopic properties of the system are known. For eg. The gaseousstate of matter can be described by parameters like Pressure (P), Volume

(V), Temperature (T) etc. The values of these parameters change when thematter is in liquid state. Thus, the state of a system is defined by specific

measurable macroscopic properties of the system.

The initial state of system refers to the starting state of the system

before any kind of interaction with its surroundings.The final state of system refers to the state after the interaction of

system with its surroundings. A system can interact with its surroundings

by means of exchange of matter or heat or energy or all.The variables like P,V,T, composition (no. of moles) `n' that are used to

describe the state of a system are called as state variables or state

functions. When the state of the system changes, the values of the statevariables of the system also change. Thus, state functions depend only on

the initial and final states of system and not on how the changes occur.Also, if the values of state functions of a system are known, all other

properties like mass, viscosity, density etc. of the system become specified.


23/25

For specifying a state of the system, it is not necessary to know all thestate variables, since they are interdependent and only a few of them (state

variables) are sufficient. A system which satisfies the conditions of thermal,mechanical and chemical equilibria and contains the macroscopic

properties which are independent of time is said to be in thermodynamicequilibrium.

Thermodynamic equilibrium sets the condition that there should beno flow of heat from one portion or part of the system to another portion or

part of the same system. ie. temperature of the system remaining constant atevery point of the system.

Mechanical equilibrium implies that there is no work done by one

portion or part of the system over another portion or part of the same

system. ie. Pressure of the system being constant at all its points._69Chemical equilibrium demands that the composition of one or more

phases of chemicals present in the system should remain constant.12.2.2 Thermodyanamic processes

A thermodynamic (physical or chemical) process may be defined as thepathway of series of intermediate changes that occur when a system is

changed from initial to final state. Processes starting with the same initialstate and ending at different final states correspond to different

thermodynamic processes.

Different types of processes are commonly used in the study of

thermodynamics.Isothermal process is defined as one in which the temperature of the

system remains constant during the change from its initial to final states.During the isothermal process, the system exchanges heat with its

surroundings and the temperature of system remains constant.

Adiabatic process is defined as that one which does not exchange heat

with its surroundings during the change from initial to final states of thesystem.

A thermally and completely insulated system with its surroundings canhave changes in temperature during transformation from initial to final

states in an adiabatic process. This is because, the system cannot exchangeheat with its surroundings.

Isobaric process is that process in which the pressure of the system

remains constant during its change from the initial to final state.

Isochoric process shows no change in volume of system during itschange from initial to final state of the process.

Cyclic process: The process which brings back the system to its

original or initial state after a series of changes is called as cyclic process.Spontaneous process are those that occur on their own accord. For

example heat flowing from a hotter end of a metal rod to a colder end. In

these processes, the transformation of the system from initial, to final stateis favourable in a particular direction only. Many of the spontaneous

processes are natural processes and are also, irreversible processes.

Non-spontaneous process are those that does not occur on their own

accord. For example, although carbon burns in air evolving heat to form


24/25

carbon dioxide, on its own carbon does not catch fire and an initial heatsupply is required. Since many of the non-spontaneous processes are slow

processes, they also exist as equilibrium processes.

Reversible process. In a reversible process the series of changes

carried out on the system during its transformation from initial to final state

may be possibly reversed in an exact manner.

This is possible when the changes are carried out very slowly in manysmaller steps on the system during its change from initial to final state. By

doing so, each of its intermediate state will be in equilibrium with itssurroundings. Under such conditions the initial and final states of the

system become reversible completely.

For example, when ice melts a certain amount of heat is absorbed. The

water formed can be converted back to ice if the same amount of heat isremoved from it. This indicates that many reversible processes are nonspontaneous

processes also.

Irreversible Process

An irreversible process is one which cannot be retraced to the initial

state without making a permanent change in the surroundings. Many of thespontaneous processes are irreversible in nature.

For eg. Biological ageing is an irreversible process. Water flowing

down a hill on its own accord is an irreversible process.Some of the characteristics of thermodynamically reversible and

irreversible processes are compared as below:

When the products of a chemical reaction do not react back to give the

reactants, then the reaction is called as irreversible reaction.

In reversible reactions in a closed system, when the rate of forwardreaction equals the backward reaction, equilibrium state is reached. The

equilibrium concentrations do not change with time.

For a general equilibrium reaction,aA + bB cC + dD,

the equilibrium content, Keq is given by [C]c [D]d / [A]a [B]b.

For gaseous reaction Keq can be expressed in partial pressures alsowhich is `Kp' value.

Keq value depend on Temperature, pressure, and equilibriaconcentrations and does not depend on catalyst and initial

concentrations.

Concepts of chemical equilibrium also applies to physical equilibrialike solid to liquid, liquid to vapour and solid to solid physical statetransformations which take place at constant temperature.

When the places of the reactants and products in the equilibriumreaction are different like in solid (or) in liquid state then heterogeneousequilibrium is formed. In the equilibrium constant expression, the

activities of pure solid and pure liquid form of reactants (or) productsare taken as unity.

Basic concepts of chemical kinetics used in writing the rate law of ageneral reaction along with order and rate constant units and various


25/25

expressions are understood.

Identification of rate determining step examples of reactions withmeasurable rates are studied. Decomposition of N2O5 reaction with

various forms of rate expressions are studied.

Order and molecularity are differentiated and various experimental

methods of determination of order of the reaction was understood. Classification of rates based on the order of the reaction are understoodwith suitable examples each of the zero, first, second, pseudo first, third

and fractional order reactions.

Order Unit of k

Zero mol litre-1 time-1I time-1

II litre mol-1 time-1III litre2 mol-2 time-1nth litre(n-1) mol(1-n) s-1

chemistry terms 1

Documents