Dr. ChildsFall, 2005

Science Laboratory

Matter and Changes in Matter

Matter

MatterMatter is everything that we see and

many of the things we don’t see (as air). By definition matter has mass and occupies space.

Matter is classified into two major categories:- Pure substances - Mixtures

Pure silver

Brass(mixture of copper & zinc)

Matter

Matter can be changed. These changes may involve physical changes in which the composition of the matter is not changed or chemical changes in which the composition is changed.

Ice melting

Candle burning

Pure SubstancesPure substances:

- contain the same type of particles throughout.- have a definite composition.- may be either elements or compounds-

sodiumNa

sodium chlorideNaCl

chlorineCl

Types of Matter

Matter

Substance Mixture

Element Compound Homogeneous Heterogeneous

Elements & Compounds

Elements & Compounds

• An element is a pure substance that cannot be broken into anther substance (by ordinary chemical means). Composed of only a single type of atom.

• A compound is a pure substance composed by two or more elements

How about some examples?

• Many things are made of elements. For example, aluminum is used for foil and for building cars and trailers.

Elements

Note: If its on the periodic table its an element!

ElementsGold

Lead

Sulfur

Oxygen

Sodium lamp

Hydrogen fuel

Elementsmagnesium wheels

chromium wheels

silicon sealant

lithium grease

carbon fiber

titanium clubs

Compounds

Compounds are formed when two or more atoms of two or more elements combine chemically (bonding!).

- fixed ratio of elements with a definite formula - separation into elements requires chemical procedures

Water H2O

Note: Compounds are NOT on the periodic table.

Compounds

table saltNaCl

table sugarC6H12O6

Carbon dioxideCO2

Nitrous oxideN2O

rustFe2O3 Epsom salts

MgSO4

Sodium hydroxideNaOH

Mixtures

MixturesMixtures are materials made up of two or more pure substances.

Mixtures can be separated by physical means based on physical properties:

evaporation filtrationfloating magnets

Mixtures may be eitherhomogeneous (solutions)heterogeneous

Mixtures

Mixture

HomogeneousEvenly mixed

HeterogeneousUnevenly mixed

MixturesHomogeneous mixture of metal are “alloys”. Alloys include brass, steel, and white gold.

Homogeneous mixtures in which one substance is dissolved in another is a “solution”. Solutions include coffee, IV fluids, and fog.

Examples:

Sea water water and saltCoffee coffee, sugar, creamBlood red cells, white cells, plasmaAir nitrogen, oxygen, CO2

Brass copper, zincWhite gold gold, silver, platinum

Homogeneous Mixtures

Brass Coffee

Bloodcolored water

Corn flakes

Salt waterjello

Homogeneous Mixtures

Examples:

raisin bran cereal with raisinschocolate chip cookietossed salad lettuce, tomatoes, carrotspizza pizza with meat, cheesegranite feldspar, micaItalian dressing oil, water, spice

Heterogeneous Mixtures

Raisin Bran

Granite

MarbleMuddy water

Tossed salad

Heterogeneous MixturesItalian dressing

Chocolate Chipcookie

Separating Mixtures

evaporation

salt pondsevaporation

filtration

distillation

Separating Mixtureschromatography

electrophoresis

centrifugation

Physical and ChemicalChanges

Physical & Chemical Properties

Be sure to know the difference between:

- Physical properties &chemical properties

- Physical changes &chemical changes

Physical Properties

Physical properties can be observed without a chemical reaction.

Examples:

color: water is clear, table salt is whitedensity: aluminum has a density of 2.7 g/cm3

state: oxygen is a gas at room temperature

magnetism: iron is attracted to magnet

texture: gold is shiny

Physical Properties

What are some physical properties of:

sulfur?

lemonade?

dish soap?

Physical ChangesIn a physical change substances are not altered

chemically, including:

state changes solid liquidliquid gas

mixing or separatingadding sugar to coffee evaporating sea water for salttearing paper

Physical ChangesState Changes

liquid solid “freezing” water to ice

liquid gas “evaporation” water to steamgasoline to vapor

solid gas “sublimation” dry ice to CO2

freezing evaporationsublimation

Physical ChangesState Changes

solid liquid “melting” ice to waterice cream melting

gas liquid “condensation” ice to water

melting

condensation

Physical Changes

Planing wood

Physical changes may involve changing shape but not composition;

Sawing wood

Breaking glass

Chemical Properties

Chemical properties: The properties of an element or compound

in a chemical reaction

Examples:

gasoline is flammable

water can be separated by electrolysis

neon is inert

Chemical changesChemical reactions:

- yield new substances

- usually cannot be easily reversed

- may either require or release energy (light, heat, etc.)

Sugars in wood may be split by burning. Combustion yields new substances: CO2 and water and heat and light energy.

Chemical Changes

Toasting bread

FireworksCandle burning

Digesting food

Combustion

Chemical Changes

photosynthesis

bread rising

food cooking

rustingbatteries

The End