Across

2. Compounds containing only a metal, carbon and oxygen.
4. A hard form of limestone used to make statues.
5. This has two oxygen atoms per molecule.
10. Chemical reaction between a substance and oxygen in the air.
11. This is called natural gas, and is used in our Bunsen burners.
12. Results shown clearly, often on squared paper.
15. A chemical compound containing oxygen and one other element.
16. Medium sized lumps of a substance.
18. Element in milk needed for strong, healthy bones.
19. A finishing substancein a chemical reaction.
20. Without this gas we would suffocate.
21. This means to appraise your completed experiment.

Down

1. A way of writing down a chemical reaction (4,8).
3. The element present in all organic compounds.
6. Chemical reaction between an acid and an alkali.
7. Very difficult to take in the other direction.
8. A word that means burning.
9. Acid rain results from the burning of this yellow element.
13. Oil, gas and coal (6,4).
14. Used to galvanize steel in order to reduce corrosion.
17. A starting substance in a chemical reaction.