Properties of Matter

Matter: anything that has mass and takes up space

Substance: matter that has a uniform and unchanging composition.

An element is a substance that has only one kind of atom.

Gold A compound is a substance that has two or more types of atoms in fixed proportions.

Water (H2O)

Substances are identified by their...

Physical and Chemical properties

Substances are identified by their...

Physical and Chemical properties

Physical properties can be observed and measured WITHOUT permanently changing the material.

Observable physical properties:

Color, shape, hardness, odor, texturestate of matter (solid, liquid or gas)luster (how light reflects off of it)

Measurable physical properties:

Density-mass contained in 1 mL of

material

Melting point-Temperature at which

material begins to melt

Freezing point-Temperature at which

material begins to freeze

Boiling point-Temperature at which

material begins to boil

Chemical properties can only be observed or measured by PERMANENTLY CHANGING the material.

Examples:

Flammability, toxicity (how poisonous it is), acidity, radioactivity, reactivity with oxygen, light sensitivity

Physical Change Chemical Change

•melting •Light or flamegiven off

•boiling •Color/odor change

•evaporatingdissolving•Forming a solid

•freezing •Temperaturechange•grinding

•Gas bubblesformed•cutting

Chemical or physical change?

1. When heated, a substance goes from a liquid to a gas.

2. When heated, the color of a substance changes from blue to white.

3. When heated, a substance burns.

PHYSICAL!

CHEMICAL!

CHEMICAL!

Chemical or physical change?

4. When hit with a hammer, a substance explodes.

5. When hit with a hammer, a substance flattens.

6. When hit with a hammer, a substance breaks apart into smaller pieces.

CHEMICAL!

PHYSICAL!

PHYSICAL!

Chemical or physical change?

7. When water is added to a blue liquid, it changes to a lighter blue.

8. When a clear liquid is added to a blue liquid, a white solid is formed.

9. When water is added to a blue liquid, it forms a blue layer and a clear layer.

PHYSICAL!

CHEMICAL!

PHYSICAL!

Indicators of chemical change

• A color change

• Gas evolution (bubbles)

• Precipitate (solid) formation

• Temperature change

• Energy given off (light or flames)

Mixture: a combination of two or more substances.

The composition of mixtures is variable.

Uh oh!

Heterogeneous mixture: a mixture in which the physical properties are different in different parts of the mixture.

heterogeneous

Homogeneous mixture: a mixture in which the physical properties are the same throughout.

A solution

soluble dye

Types of solutions

Gas/gas

Gas/liquid

Liquid/liquid

Solid/liquid

Solid/solid

Air is 78% N2 and 21% O2

Carbonated sodas are made by dissolving CO2 gas in water

8 carat gold is a solid solution of Cu, Ag and Au

Vinegar is 5% acetic acid, 95% water

Sports drinks are 0.1% NaCl, 5% sugar and 94.9% water.

Colloids: very small particles are suspended in solution

Gold/silver alloy particles in glass

Water droplets in air

Tyndall Effect: Scattering of light off of colloidal particles

No Tyndall effect = not a colloid

Separating Mixtures

Mixtures can be separated by taking advantage of differences in physical properties.

Filtration: a porous barrier is used to separate a solid from a liquid.

The filter can only separate out particles of solid that are LARGER than the pores through the filter.

Distillation: separation of substances by differences in boiling point.

The substance with the lower boiling point will distill off first.

Crystallization: formation of a pure solid substance from a solution containing the dissolved substance.

Sodium acetate in water

p-dichlorobenzene in chloroform