Review

Week 9 BenchmarkOctober 22, 2013

Pure Substances

• A sample of matter that has definite chemical and physical properties.

Elements• pure substance that cannot be separated into

simpler substance by physical or chemical means.

Compounds

Pure substance composed of two or more different elements joined by chemical bonds.

– Made of elements in a specific ratio that is always the same– Has a chemical formula– Can only be separated by chemical means, not physically

1.

Which of the following is a pure compound?

A B

C D

2.

Which process best demonstrates a chemical change in distilled water?

a. Freezing the water b. Calculating the water's density c. Dissolving sugar in the water d. Separating the water into its elements

3.

Octane, a component of gasoline, can be represented by the chemical formula C8H18. What type of substance is octane?

a. compoundc. heterogeneous mixtureb. elementd. homogeneous mixture

Mixtures• A combination of two or more pure

substances that are not chemically combined.

• substances held together by physical forces, not chemical

• No chemical change takes place • Each item retains its properties

in the mixture • They can be separated physically

Chem4kids.com

Mixtures vs. Compounds

http://www.bbc.co.uk/schools/ks3bitesize/science/chemistry/elements_com_mix_6.shtml

Mixtures• Some mixtures are more pure than others.

– Heterogeneous mixture – Uneven distribution of substances. (Very impure)

- You can see the different parts.

Examples: SandGraniteWood

Mixtures

• Homogeneous Mixture – Components are evenly mixed. (More pure than heterogeneous)

Salt water contains salt and water, but are mixed all the way to the atomic level

- Cannot see the parts.

level, but it can still be separated by physical means. Seawater distillation plant

Properties of Matter• Identify each of the following items as a mixture or a pure substance.• - If a mixture, identify as homogeneous or heterogeneous.• - If a pure substance, identify as a compound or an element.

Sample Type of Sample Type of Mixture or Pure Substance

Gold

Water

Italian Dressing

Milk

Cobalt

Coffee

Calcium Carbonate

Cake Batter

4.

A mixture made up of different substances that can be easily seen is a:

a. normal mixture b. homogeneous mixture c. heterogeneous mixture d. compounded mixture

Chemical or Physical Change

Did it change size, shape, color or state?• Crushing aspirin• Cutting paper• Paint a wall• A bottle of water froze

Did a new substance form?• Metal rusted• 2 clear and colorless solutions formed a yellow

precipitate

Properties of Matter

• Identify the following properties as physical or chemical.Property Physical Property Chemical Property

Temperature

Bond Strength

Calorie Content

Mass

Density

Reactivity

Length

Melting Point

5.

When two clear solutions are mixed in a chemistry lab, a yellow precipitate forms and settles to the bottom of the beaker. The total mass of material inside the beaker does not change when the solid precipitates. Which statement is a reasonable conclusion about the formation of the precipitate?

a. It is a physical change because precipitates are a change of state.

b. It is a physical change because the total mass does not change.c. It is a chemical change because a new material was formed in

the beaker.d. It is a chemical change because physical changes do not

produce solid products.

6.Which one of the following statements is true of chemical or physical

changes?

a. Candles burning is a physical change. b. The release of a great deal of heat when magnesium is dropped in

hydrochloric acids indicates that a chemical change has occurred. c. The solidification of wax is a chemical change. d. Dissolving salt in water is a chemical change.

7.Rust (Fe2O3) forms on an iron (Fe) pipe after prolonged exposure to humid

air. What type o of change does this illustrate?

a. Mechanical b. Physical c. Chemical d . Nuclear

How can you identify extensive and intensive properties?

• An extensive property is a property that depends on the amount of matter in a sample. Mass and volume are examples of extensive properties.

• An intensive property is a property that depends on the type of matter in a sample, not the amount of matter.

• Every sample of a pure substance has identical intensive properties because every sample has the same composition. Hardness, color, conductivity, and malleability are examples of intensive properties.

1. Identify A student measures out a sample of sucrose (table sugar) for an experiment. What are some extensive properties of the sample? What are some intensive properties of the sample?

1. Identify A student measures out a sample of sucrose (table sugar) for an experiment. What are some extensive properties of the sample? What are some intensive properties of the sample?

Properties of Matter

• Identify the following properties as extensive or intensive.

Property Extensive Property Intensive Property

Temperature

Bond Strength

Calorie Content

Mass

Density

Reactivity

Length

Melting Point

8.

Which of the following is an extensive property of coffee in a mug? a. percent sugar b. total mg of caffeine c. temperature d. cream added per mL of coffee

9.

Which of these is an extensive property of a wax candle?

a. The temperature at which it burnsb. The color of the flame that it producesc. The amount of heat produced by burning the

entire candled. The color of the wax that the candle is made

of

10.

Which of the following is an intensive property of a sugar solution?

a. volumeb. sweetnessc. densityd. mass

Name the Group

• Elements from which group will form salts and will combine in a 1:1 ratio with elements from group 1A?

• What is the name of the group that contains elements that are the least reactive?

• What is the name of the group that contains metals that are the most reactive?

• Iron and copper are in the group called the ____________ metals.

Diatomic Molecules

• Name the 7 diatomic molecules: (Hint: Heavenly Seven or BrINClHOF)

Group A elements are called REPRESENTATIVE ELEMENTS divided into 3 broad classes:

METALS - have high electrical conductivity - high luster when clean - ductile (can be drawn into wires) - malleable (can be beaten into thin sheets)

NONMETALS - occupy the upper-right corner of the periodic table - they are non-lustrous and poor conductors of electricity and are brittle

METALLOIDS - elements that are intermediate between metals and non-metals (Ex. Silicon and Germanium)

11.

Based on its position in the periodic table, what predictions can you make about the properties of the element labeled A (purple on the previous slides)?

a. The element is a poor conductor and has a shiny appearance.b. The element is a good conductor and has a shiny appearance.c. The element is a poor conductor and has a dull-looking

appearance.d. The element is a good conductor and has a dull-looking

appearance.

12.A research group needs to fill a chamber with an element that has low or

no reactivity. From which of the labeled areas in the periodic table above should they be choosing?

a. Q (far left) b. R (center) c. S (along stairstep line) d. T (far right)

13.

A violent reaction occurs when sodium is placed in water. Which would produce a similar reaction with the water?

a. Mg B .S c. K d. Cr

14.

The elements from which of the following groups are most likely to react with potassium (K)?

a. Group 2 b. Group 7 c. Group 13 d. Group 17

15.

The alkali metals are located in which group of the periodic table?

a. 1 b. 2 c. 3 d. 4

IONIC BOND

• IONIC BOND-forms between a metal and a nonmetal. Involves a transfer of electrons.

OXIDATION NUMBERS

• OXIDATION NUMBER-the number of electrons lost or gained during bonding. We can predict this from our periodic table.

IONIC BONDS-WRITING FORMULAS• Total number of electrons gained by nonmetal must equal number of

electrons lost by the metal, resulting in an overall charge of zero.

• Ex. Na+1 Cl-1 (+1) + (-1) = 0 NaCl

• Ex. Mg+2 Cl-1 we will need 2 chlorines to cancel out one magnesium…..

(+2) + (-1)+(-1) =0 MgCl2

16.

The ability of salt to preserve food was a foundation of civilization because it eliminated man’s dependence on the seasonal availability of food and allowed travel over long distances. Given the chemical formula for salt is NaCl, what is the correct chemical name for salt?

a. Sodium chloriteb. Sodium chloratec. Sodium chlorided. Sodium chlorine

17.

The chemical formula for calcium chloride is

a. Ca2Cl

b. CaCl2

c. CaCld. Ca2Cl3

COMMON POLYATOMICS

NO2-1 nitrite

NO3-1 nitrate

CO3-2 carbonate

SO3-2 sulfite

SO4-2 sulfate

PO4-3 phosphate

OH-1 hydroxideNH4

+1 ammonium

POLYATOMICS-WRITING FORMULAS

Na+1 NO3-1 Formula????

NaNO3

Mg+2 NO3-1 Formula????

Mg(NO3)2

If more than one polyatomic ion is needed, place parentheses around and write subscript outside. Never change subscripts of the atoms within the ion!!!!!

18.

According to this information, what is the chemical formula for aluminum sulfate?

a. AlSO4

b. Al3(SO4)2

c. Al2(SO4)3

d. Al6SO4

19.

If the formula for chlorate and the chlorite ions are ClO3

- and ClO2-, respectively, then the

formulas for iodate and iodite, respectively, are _____.

a. I-, IO3-

b. IO3-, IO2

-

c. IO4-, I-

d. IO4-, IO3

-

(c) McGraw Hill Ryerson 2007

• Covalent compounds with 2 non-metal 2 non-metal atomsatoms use a system of prefixesprefixes.

See pages 194 - 195

Prefixes are often used before the atom name to indicate the number of atoms in the molecule.

Example: CO = carbon monoxide CO2 = carbon dioxide

CCl4 = carbon tetrachloride

(c) McGraw Hill Ryerson 2007 See pages 194 - 195

STEP 1: Write the most metallic atom (farthest left) first

STEP 2: Use prefixes to symbolize the # of each atom.

STEP 3: Add -ide to the end of the second atom’s name

(c) McGraw Hill Ryerson 2007 See pages 194 - 195

What is the chemical formula for the molecule trinitrogen tetrachloride?

What is the name of the molecule Si3P6?

N3Cl4

Trisilicon hexaphosphide

20.

Which of the following is the name of the molecule PCl3?

a. Phosphorus trichlorideb. Potassium trichloridec. Phosphorus chlorided. Potassium chloride

Objective: Compare…

Describe the KE of molecules…

21.

A certain substance has a definite shape and volume and its particles do not move fast enough to overcome the attraction between them. What do these properties indicate about the state of the substance?

a. It is a solid.b. It is a liquid.c. It is a gas.d. It is a plasma.

Where is the smell coming from and how does it spread out?

Diffusion occurs in liquids and gases but hardly at all in solids.

What is diffusion?Diffusion is the movement of particles that allows them to spread out and mix with other particles.

For example, the smell of aftershave or perfume diffuses and is detected by people on the other side of the room.

Use the particle model to explain these facts about diffusion:

Diffusion happens more quickly for gases than for liquids.

Diffusion happens more quickly at warm temperatures than at cooler temperatures.

22.

Diffusion is a term for the movement of molecules from ______.

a. an area of low concentration to an area of high concentrations.

b. an adjacent area to a gradient area.c. an area of high concentration to an area of

low concentration.d. a nucleus to a mitochondria.

Conservation of energy

• The law of conservation of energy states that in any chemical or physical process, energy is neither created nor destroyed.– During any chemical or physical process, the energy of

the universe remains unchanged.– If the energy of the system increases during a process,

the energy of the surroundings must decrease by the same amount.

– If the energy of the system decreases during a process, the energy of the surroundings must increase by the same amount

Endothermic process

• Heat is absorbed from the surroundings in an endothermic process.– In an endothermic process, the system gains heat

as the surroundings lose heat.– Heat flowing into a system from its surroundings is

defined as positive; q has a positive value here.

Exothermic process

• An exothermic process is one that releases heat to its surroundings.– In an exothermic process, the system loses heat as

the surroundings gain heat.– Heat flowing out of a system into its surroundings

is defined as negative; here, q has a negative value.

23.

A solid object at 30°C is placed inside a container of liquid at 60°C. What most likely will be observed?

a. The temperature of the liquid will remain the same.b. The temperature of the solid object will decrease.c. The temperature of the liquid will increase.d. The temperature of the solid object will increase.

• Use your experience and the words below to write a definition for conductionconduction.

Transfer Heat EnergyContact Touching

Substances

Between

• Use your experience and the words below to write a definition for radiationradiation.

TransferHeat Energy

EmissionRadiation

Substances

BetweenAll directions

• Use your experience and the words below to write a definition for convectionconvection.

TransferHeat Energy

Hot

Movement

Particles

Rises Air or LiquidCold

Sink

24.

Molten rock rises in Earth’s mantle and then sinks back toward the core in a circular pattern, as shown in the diagram. This method of heat transfer is known as —

a. conductionb. radiationc. vibrationd. convection

25.

The moon’s surface becomes hot during the long lunar day because the sun transfers heat to the moon. This heat transfer is accomplished almost entirely through the process of —

a. convectionb. conductionc. refractiond. radiation