Chapter 2 Outline
I.
Composition of Matter
A. Matter
1. Anything that has mass and occupies space
2. Anything with inertia
3. Two kinds of matter
(a) Mixtures – variable composition
(b) Substances – constant composition
B. Composition of Matter
1. Have constant composition
2. Cannot be broken down or separated by physical means
3. Two kinds of substances
(a) Elements
(i)
Substances that are made up of only one type of atom
(ii)
Examples: gold, silver, oxygen, copper, hydrogen, sulfur
(b) Compounds
(i)
Substances that are made up of more than one type of atom
Examples: water, table salt, sodium bicarbonate (baking soda), carbon dioxide,
sugar
C. Mixtures
1. Two or more substances physically combined
2. composition varies from sample to sample
3. Examples: dirt, salt water, jelly
(a) Homogeneous
(i)
Also called a solution
(ii)
Only one phase
(iii) Materials are evenly spread out
(iv)
Examples: salt water, toothpaste, air, bronze, brass
(v)
Particles do not settle and do not scatter light
(vi)
Can be made of gases, liquids, or solids
(b) Heterogeneous
(i)
Individual components can be easily distinguished
(ii)
Examples: pizza, dry soup, salad, concrete, nachos, tacos
(iii) Suspensions contain a liquid in which visible particles settle
Examples: Italian dressing, muddy water
(iv)
Colloids contain particles which do not settle but will scatter light.
Examples: milk, jelly, fog
Solution
Example
Heterogeneous/
Called
homogeneous
Gas-gas
Carbon dioxide and oxygen in nitrogen Heterogeneous
Air
Liquid-gas
Water vapor in air
Heterogeneous
Fog
Gas-liquid
Carbon dioxide in water
Unopened – homogeneous
Soda
Liquid-liquid
Acetic acid in water
Homogeneous
Vinegar
Solid-liquid
Sodium chloride in water
Homogeneous
Salt water
Solid-solid
Copper in silver
Homogeneous
Sterling silver
Chapter 2 Outline
II.
Describing matter
A. Physical Properties
1. Characteristics of matter that can be observed without changing the identity of the substance
(a) Some describe appearance – shape, color, odor, texture, phase
(b) Some can be measured – length, mass, density, volume, temperature, boiling point,
melting point
(c) Some describe the behavior of a substance – attracted to a magnet, buoyancy, viscosity
2. Physical properties can be used to separate a mixture
(a) Sand, salt, pebbles, iron filings, beans
B. Chemical Properties
1. Describe how a substance reacts or fails to react when brought in contact with another
substance.
(a) Examples: burns, flammability, explodes, bubbles, precipitates, changes color, changes
odor
C. Physical Properties
1. Changes which do not change the identity of the substance(s)
(a) Examples: melting, dissolving, tearing, Cutting, freezing, boiling
Self Test 1
 Odor is a chemical property
 Boiling points are physical properties
 Melting is a chemical change
 The ability of wood to float is a physical property
 The fact that paper burns is a chemical property
D. Chemical Changes
1. Changes which alter the identity of the substance
2. Occur during a chemical reaction
3. Evidence of a chemical change:
(a) Production of light, heat, sound
(b) Absorption of heat (container gets cold)
(c) New color or odor
(d) Appearance of a new substance
(i)
Gas –effervescence (bubbling)
(ii)
Solid – precipitate
Self Test 2
 Paper burning is a chemical change
 Salt dissolving in water is a chemical change
 ice melting is a chemical change
 Wood burning is a chemical change
 Fruit rotting is a chemical change
III.
Law of conservation of mass
A. During a chemical change, matter is neither created or destroyed
B. Mass before a reaction must equal mass after a reaction