Across

1. How much space something takes up

4. How much matter is in something

5. A material dissolved in a liquid

8. Something light cannot pass through

9. A particle that cannot be divided with everyday tools

11. A new material formed when something combines with oxygen

13. What iron does when it reacts with oxygen

16. Something that has mass and takes up space

17. The state of matter that has a fixed shape and a fixed volume

18. Some light passes through it and some does not

Down

2. Something that has mass and takes up space

3. What water is doing at 212ºC

4. What a solid does when you add heat

6. A material that is not in the gas state and not in the solid state

7. The change from gas to liquid

10. Two pure materials scrambled together

12. Either an atom or a molecule

14. Oxygen is one of these

15. It keeps you from floating off into space