Properties and Changes of Matter
Properties of Matter
Properties can be either physical or chemical
1. Physical – any properties that can be observed or measured without
forming a new substance. E.g. Colour, texture, density
2. Chemical – any properties that describe how substances react with
one another when forming a new substance.
E.g. Combustibility – the ability of a substance to burn
Light sensitivity – hydrogen peroxide breaks down into water
and oxygen gas when exposed to light.
Changes in Matter
There are two types of changes in matter:
1. Physical
- no new substance is formed
- Properties may change but the particles are not
changed
- most of the time can be reversed
- Examples: melting ice (changes of state), cutting up
carrots
2. Chemical
- at least one new substance with new properties
is formed.
- very difficult to reverse
- Recharging batteries is reversible
- Examples: burnt toast, burning paper
Clues that a CHEMICAL change has occurred:
1. Bubbles are produced (formation of gas)
2. Color change
3. Starting material is used up, therefore hard to reverse
4. Heat or light is produced or absorbed (temperature change)
5. A solid appears in a liquid solution (precipitate)
Homework: Read pp. 175-177; p. 178#2-11