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Classification of Matter

• physicalphysical changechange: the chemical composition (makeup or parts) of the matter stays the same.– Ex: state changes (solid to liquid to gas),

changing shape (ripping, squishing)

• Can be used to separate a mixture into a pure substance, but not a pure substance into its elements.

• chemicalchemical changechange: a compound’s chemical composition (makeup) is changed – it becomes a new substance– ex: burning, rusting, reacting

Chemical or Physical Change?1. burning paper2. folding a piece of paper3. the reaction of KI and

Pb(NO3)2

4. combustion of gasoline5. hammering gold into a ring6. cutting a diamond7. acid rain “melting” a statue8. a pile of old iron rusting9. separating water into H

and O by using electricity

MATTERMATTER

MixtureMixture PurePureSubstanceSubstance

HomogeneousHomogeneousMixtureMixture

HeterogeneousHeterogeneousMixtureMixture

CompoundCompound ElementElement

AtomAtom

Physically separated

Chemically separated Can’t be separated

• mattermatter: has volume (takes up space), and mass– can be solid, liquid or gas

• mixturemixture: several different substances NOT chemically combined, can be physically separated into pure substances– homogeneoushomogeneous: evenly mixed (solution)

• ex: salt water, air

– heterogeneousheterogeneous: not evenly mixed• ex: sand, soup

• pure substancepure substance: constant (same) composition, – ex: water H2O or lead Pb

• compoundcompound: chemically bonded elementsex: CO2

• elementelement: can not be separated physically or chemically, made of a single kind of atom

• atomatom: smallest particles of an element, can not be chemically separated

ELEMENTELEMENT COMPOUNDCOMPOUND MIXTUREMIXTURE

MOLECULESMOLECULES

MonMonatomicatomic DiDiatomicatomic

ex: noble gases: He, NE, Ar, Kr… Ex: halogens: F2, Cl2, Br2, H2

ProportionsProportions PropertiesProperties SeparationSeparation

ElementElement

(copper)

Contains only one type of atom

Depend on the forces between the atoms

Can not be separated into simpler substances by chemical means

CompoundCompound

(water = bonded oxygen and hydrogen)

Always has two H atoms for every O atom

Totally different from its elements

Requires chemical change to separate a compound into simpler substances

MixtureMixture

(air = N, O, Ar, CO2…)

Can vary Similar to it’s parts

Can be separated physically

MATTERMATTER

MixtureMixture PurePureSubstanceSubstance

HomogeneousHomogeneousMixtureMixture

HeterogeneousHeterogeneousMixtureMixture

CompoundCompound ElementElement

AtomAtom

Physically separated

Chemically separated Can’t be separated

a) Matter that can be physically separated and is uniform (evenly mixed).

b) Matter that can not be physically separated.

c) Matter that can not be physically separated and can not be decomposed (broken apart) by chemical means.

d) Matter that can be physically separated. e) Matter that can be physically separated

but does not have a uniform (evenly mixed) composition.

f) Matter that can not be physically separated but can be decomposed (broken down) by chemical means.

g) Can an element be broken down chemically?

h) How is a mixture different from a pure substance?

i) How is an element different from a compound?

Homework

• Classification of Matter 1

• 2: put the word “physically” before the word “separated” in every part (a – f)

Element or compound?a) neon

b) sodium bichlorate

c) silver

d) potassium chloride

e) carbon dioxide

f) helium

a) element

b) compound

c) element

d) compound

e) compound

f) element

An unknown silvery powder has a constant melting point and does not chemically or physically separate into other substances. The unknown substance can be classified as –A. an elementB. a compoundC. a mixtureD. an alloy

Which of the following is an example of a chemical change?

A. Ice cracking

B. Sugar dissolving

C. Milk souring

D. Lead melting

Which of these describes a pollution-producing process that involves only a physical change?

A. Coal with a high sulfur content is burned, producing gases that cause acid rain.

B. Chlorofluorocarbons are released, changing ozone in the upper atmosphere into oxygen.

C. Hot wastewater is discharged into a lake, lowering oxygen levels in the water.

D. Nitrogen oxide emissions combine with water vapor, producing nitric acid.

Which of the following processes is an example of a physical change associated with an oak tree?

A. Decomposition of bark by bracket fungi.

B. Starches and sugars being broken down during energy production.

C. Water and carbon dioxide being converted to glucose.

D. Evaporation of water from the surface of the leaves.

Which of the following represents a physical property?a. Copper tarnishes to green when weathered.b. Oxygen is flammable when ignited.c. Iron rusts when exposed to oxygen.d. Ice melts if left at room temperature.

A student examines a sample of matter and finds that she can’t separate it into its parts physically or chemically. This matter is:

a. an element

b. a homogeneous mixture

c. a heterogeneous mixture

d. a gas

Which of the following represents a chemical change?

a. A piece of paper is ripped in half.

b. A piece of paper is folded in half.

c. A piece of paper is burned.

d. A piece of paper is frozen in the freezer.

One example of a pure substance is:

a. paper

b. cookie dough

c. rocks and sand

d. water

Separating a mixture

Physical or Chemical?Physical or Chemical?

PhysicalPhysical

• solventsolvent: the part of a solution doing the dissolving (the liquid)

• solutesolute: a substance being dissolved in a liquid

• solutionsolution: the mixture of a solvent and a solute

SOLUTESOLUTE

SOLVENTSOLVENTSOLUTIONSOLUTIONSOLUTIONSOLUTION

• solublesoluble: dissolves in a solvent

• insolubleinsoluble: does not dissolve

• filtrationfiltration: mixture is poured into a mesh (filter), though which the liquid passes. The solid is left behind.

• volatilityvolatility: how easily a substance becomes a gas

• distillationdistillation: separation of a mixture of liquids with different volatilities, by evaporating, condensing and collecting each liquid.

Distillation

• evaporationevaporation: a very simple distillation of a mixture when only one compound is volatile– ex: water and sand; water and salt

• chromatographychromatography: separation of a mixture made of substances of different masses that move at different speeds.

Experiment• What color is black ink?

• Is ink a mixture or pure substance?

• How could we find out?

What method would you use…

a) to separate sand from water?

b) to separate two kinds of paint mixed with one another?

c) to separate gasoline from water?

d) to separate salt from water?