EQ#6 What are the properties of matter?

What is a (Pure) Substance?

• A substance is matter that is uniform & has an unchanging composition.

• A formula can be written for a substance –Ex. H20 or 02

• A substance can be either an element or a compound.

Elements and Compounds• Element:

– Contains only 1 type of atom– Found on the Periodic Table

• Ex. O2, Fe, Na, He

• Compound:– 2 or more elements chemically

combined– Ex. H2O, C6H12O6, CO2

Physical Properties

• These are characteristics that can be observed without changing the sample’s composition.

• They are observed directly with the senses.

• Examples include: – Shape, color, density, odor, boiling

point, etc.

What are some physical properties of water?

Chemical Properties• This is the ability of a substance to

combine with other substances or change into 1 or more substances.

• It is the result of contact with another substance, or due to the application of thermal or electrical energy.

Examples of Chemical Properties:

• Iron rusts when combined with oxygen

• Water decomposes into hydrogen & oxygen

• Magnesium burns

Quiz: Physical or Chemical Property?

• Water boils at 100°C.• Silver tarnishes.• Propane burns.• Density of Al is 2.7 g/mL.• Carbon is black & brittle.• Zinc reacts in acid.

Extensive vs. Intensive Properties

• Extensive properties:– Depends on the amount of a substance

present.– Ex. Mass, volume, length

• Intensive properties:– Independent of the amount of substance

present.– Ex. Density, boiling point, reactivity

Phases of MatterPhase Definite

Shape?DefiniteVolume

DistanceBetweenParticles

Ex.

Solid Yes Yes TightlyPacked

Ice, wood

Liquid No Yes Less Close

Water,mercury

Gas No No Far apart Air, H2O vapor

• Vapor is a gaseous state of substance that is normally a solid or liquid at room temperature.

Phases (States) of Matter

Physical Changes: • Physical changes are changes that occur

without changing the composition of the substances.

• Bending, grinding, crushing, dissolving, cutting, phase changes etc.

Physical Change Examples:• Ice melting:

H2O (s) H2O (l)

• Potassium permanganate dissolving in water:

Chemical Changes:• Chemical changes are changes that

occur when substances change into new substances.

• Also called a chemical reaction.

• Exploding, rusting, oxidizing, burning, etc.

• New substances formed have a different composition & different properties.

Indicators of a Chemical Reaction:

1. Gas formation2. Solid formation

(precipitate)3. Change in color4. Change in odor5. Change in

temperature

Precipitate:

Physical or Chemical Change?

• Alcohol evaporating.• Iron rusting.• Dynamite exploding.• Sugar dissolving in water.• Water boiling.• Baking soda & vinegar

reacting.• Dry ice subliming.