State Changes
The three states of matter and the particle model: how solids, liquids and gases differ, the changes between them such as melting and boiling, and the state symbols used in equations.
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Solid, liquid, gas
Ice, water and steam are all the same substance in three different states. The particle model explains the difference by how the particles are arranged and how much they move. Heating or cooling a substance can change its state. This module covers the three states, the changes between them, and the state symbols chemists write in equations, such as (s) for solid.
States vocabulary
Learn these four terms before you study the changes.
The three states
The particle model describes each state.
Energy changes the state
A top answer explains change through energy. Heating gives the particles more energy so they move more and can break free, turning a solid to a liquid and a liquid to a gas. Cooling takes energy away and the reverse happens. Name the change precisely, and remember the state symbols: s for solid, l for liquid, g for gas, and aq for a substance in a water solution.
Match the change
- melting
- freezing
- boiling
- condensing
- a solid turning into a liquid
- a liquid turning into a solid
- a liquid turning into a gas
- a gas turning into a liquid
Match the state symbol
- s
- l
- g
- aq
- a solid
- a liquid
- a gas
- dissolved in water
Liquid to gas
What is the change from a liquid to a gas called?
- Boiling.
- Melting.
- Freezing.
- Condensing.
About gases
Select the TWO statements that are true of a gas.
- The particles are far apart.
- The particles move quickly.
- The particles are fixed in place.
- It keeps a fixed shape.
Heat the ice
Put these stages in order as ice is heated all the way to steam, earliest first.
- Ice, a solid
- It melts
- Water, a liquid
- It boils
- Steam, a gas
Complete the facts
A solid turning into a liquid is _____. A liquid turning into a gas is _____. A gas turning into a liquid is _____. The state symbol for a gas is _____. The state symbol for something dissolved in water is _____.
The liquid range
Water melts at 0 degrees and boils at 100 degrees. Subtract 0 from 100 to find the range of temperature over which water is a liquid. What is the answer in degrees?
Changes on heating
Tap the TWO changes that happen when a substance is heated.
- melting a solid into a liquid
- boiling a liquid into a gas
- freezing a liquid into a solid
- condensing a gas into a liquid
Name the change
Read each situation and choose the correct answer.
- A puddle of water dries up and disappears into the air. What change is this?
- Water is left in a freezer and turns to ice. What change is this?
- An equation shows salt dissolved in water. Which state symbol is used?
Explain the states
Explain the three states of matter and the changes between them using the particle model.
- Describe how the particles are arranged in a solid, a liquid and a gas
- Explain what happens to the particles when a solid is heated until it melts
- Name the change from a liquid to a gas and from a gas to a liquid