Materials

3. a usually irreversible change
5. a highly unreactive metal at the top of the reactivity series.
6. A reaction that transfers energy to the surroundings
9. A theory which can be tested
10. a composite material made from sand, cement and other materials
12. An elastic polymer obtained from certain trees
14. A substance which reverts back to it's original shape when it is no longer being stretched.
15. a ranking of the reactivity of different metals
16. collapsing in on itself
18. Transparent material made by heating sand with other substances.
19. a substance that lasts a long time and does not naturally break down
20. A range of hard, durable, non-metallic material

1. a material which does not react with other materials
2. a theory explaining how the forces of particles hitting the walls of a container causes pressure in gases
4. materials which are combinations of two or more other materials
7. How an experiment is conducted
8. when a substance burns chemically
11. A non-metal material which doesn't conduct electricity
13. how well a metal reacts with another substance
17. a highly reactive metal at the top of the reactivity series