Across

4. A gas at the same temperature as its liquid state
5. A measure of how hot or cold a substance is.
8. When a gas changes state to a liquid.
10. The movement of one substance through another substance.
11. A group of atoms chemically joined.
12. When a liquid cools to become a solid.

Down

1. A form of energy due molecular motion.
2. The smallest particle of an element.
3. A volume empty of free molecules.
6. Force in newtons divided by the area.
7. Change from a liquid to a gas - only at the lliquid surface.
9. When liquid changes state to a gas.