SME
Grade 7 Science · Physical Science
States of matter and phase changes
See how particles move in solids, liquids and gases, and what happens to them in each phase change.
Explore
Particles packed in rows, each wiggling in place.
Ice keeps its shape.
Assumptions
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The same particles are in every box. Only how close they are and how fast they move changes.
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Adding thermal energy makes particles move faster; taking it away slows them.
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The arrows over the boxes take in heat; the arrows under them give heat out.
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Choose a state or a change.
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.
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More problem types
Heating curve of water
Use this for “What is the temperature 30 minutes into heating the ice, and what state is it in?”
Name the change
Use this for “Which is an example of water condensing?”
Heat in or heat out?
Use this for “Which change needs thermal energy to be added?”
Solid, liquid or gas at room temperature?
Use this for “At 20 °C, is the substance a solid, a liquid or a gas?”
Water left in an open cup
Use this to record how much water is left in an open cup each day.