Unit 2 – Matter

Classification of Matter

Properties of Matter

A. Matter Flowchart

MATTER

Can it be physically separated?

Homogeneous Mixture

(solution)

Heterogeneous Mixture Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically decomposed?

noyesIs the composition uniform?

noyes

Colloids Suspensions

Pure Substances

1. Element composed of identical atoms EX: copper wire, aluminum foil

Pure Substances

2. Compound

composed of 2 or more elements in a fixed ratio

properties differ from those of individual elements

EX: table salt (NaCl)

Mixtures

Variable combination of 2 or more pure substances.

Heterogeneousuneven distribution

(suspensions & colloids)

Homogeneouseven distribution

( solutions)

Mixtures

1. Solution homogeneous very small particles no Tyndall effect Tyndall Effect

particles don’t settle EX: rubbing alcohol

Mixtures

2. Colloid heterogeneous medium-sized particles Tyndall effect particles don’t settle EX: milk

The Tyndall Effect

Colloids scatter light, making a beam visible. Solutions do not scatter light.

Which glass contains a colloid?

solutioncolloid

Mixtures

3. Suspension heterogeneous large particles – can see Tyndall effect particles settle

(needs to be shaken) EX: fresh-squeezed

lemonade

Mixtures

Examples:

jello

muddy water

Fog

saltwater

Italian salad dressing

colloid

suspension

colloid

solution

suspension

Mixtures vs. Compounds

Components may be in any proportion

Individual components retain their own identities

Components may be separated physically

When mixture is formed there is little to no evidence of a reaction

Components are in fixed proportions

Individual components lose their identities, new set of properties result

Components may be separated only chemically

When compound is formed there is evidence of a reaction

Physical Separation Techniques

Difference in Densities (density column – some objects float in others)

Filtration (separate solids from liquids)

Magnetism Chromatography Distillation (separation by boiling

points)

Separation of a MixtureSeparation of a Mixture

The constituents of the mixture retain The constituents of the mixture retain their identity and may be separated by their identity and may be separated by physical means.physical means.

Separation of a MixtureSeparation of a Mixture

The components of dyes such as ink may be separated by paper chromatography.

Separation of a MixtureSeparation of a Mixture

Distillation

Types of Properties

PhysicalProperties that

describe the substance itself, rather than describing how it can change

Example: boiling point, color, size

ChemicalProperties that

describe the substances ability to undergo changes that transform it into other substances

Example: charcoal has the ability to burn in air

Types of Physical PropertiesTypes of Physical PropertiesExtensive propertiesExtensive properties

Intensive propertiesIntensive properties

Volume

MassEnergy Content (think Calories!)

depend on the amount of matter that is present.

do not depend on the amount of matter present.

Melting point

Boiling point

Density

Changes in Matter

Physical Change

Change in form or state of matter without altering chemical composition

Examples: slicing a banana, boiling water, dissolving sugar

Chemical Change

Changing substance into new substance by reorganizing atoms…chemical bonds are made or broken

Examples: burning, rusting, copper turns green

5 Indicators of a chemical change

Color Change Light emitted (glow sticks, candle

burning) Temperature change (happens on its

own – you don’t supply heat) Precipitate forms (solid from 2 liquids) Gas production (you see bubbles)

Three PhasesThree Phases

Solids

Definite shape/definite volume

Molecules are tightly packed, but can still move slightly

Most Dense state of matter (because particles are the closest)

Liquids

Definite volume/no definite shape (takes the shape of its container)

Fluid – because it “flows”

Particles are not as close as solids, but are more dense than gases

Gases

No definite shape or volume

Least dense of the 3 states of matter because the particles are far apart

Which state of matter are they?

Phase Phase DifferencesDifferences

SolidSolid – definite volume and shape; particles packed in fixed positions.LiquidLiquid – definite volume but indefinite shape; particles close together but not in fixed positionsGasGas – neither definite volume nor definite shape; particles are at great distances from one another

Phase Changes

Freezing (liquid to solid) Melting (solid to liquid) Evaporation (liquid to gas) Condensation (gas to liquid) Sublimation (solid to gas) Deposition (gas to solid)

**** Phase changes are PHYSICAL changes!!!!