States of Matter and Chemical Reactions
This page covers the characteristics of solids, liquids, and gases in science, as well as chemical and physical reactions.
States of Matter
The guide explains the properties of solids, liquids, and gases:
Solids:
- Have a fixed shape
- Cannot be squashed
- Examples: brick, stone, wood
Liquids:
- Flow but maintain contact
- Examples: water, juice, washing-up liquid
- Melting point: 0 degrees Celsius
- Boiling point: 100 degrees Celsius
Gases:
- Flow easily
- Examples: oxygen, nitrogen, helium
Chemical and Physical Reactions
The page distinguishes between chemical and physical reactions:
Chemical reactions:
- Cannot be reversed
- Signs include temperature change, bubbles/fizzing, color change, and solid formation
Example: A burning candle is a chemical reaction that cannot be reversed.
Physical reactions:
- Can be reversed
- Example: Ice melting and refreezing
Chemical Equations
The guide introduces word equations and provides an example:
Example: Magnesium + hydrochloric acid → magnesium chloride + hydrogen
Forces
The page briefly touches on balanced and unbalanced forces:
- Balanced forces: Equal and opposite forces (e.g., 2N - 2N = 0N)
- Unbalanced forces: Unequal forces resulting in movement (e.g., 2N + 3N = 5N)
