Across

1. Burning something in air.
4. Chemical reaction with oxygen.
6. Produce palatable food by application of heat.
8. An atom with an excess positive or negative electric charge.
9. A tiny particle, much lighter than an atom, that carries a negative electric charge.
15. Fossil fuel raw material used to make most plastics.
16. A fraction of crude oil that is used in buses and lorries as a fuel.
17. A positive ion that travels towards the negative cathode.
18. Where new chemical products form from chemical reactants.

Down

1. To react metal with the atmosphere and water.
2. A chemical building block used to form plastics.
3. A technique used to separate liquids with different boiling points.
5. A negative ion that travels towards the positive anode.
7. Fossil fuel used in jet aircraft, also called kerosene.
10. A substance that increases the rate of a chemical reaction but that is not used up itself.
11. Breaking long chain hydrocarbon molecules into more useful short chain molecules.
12. Genereal name for a polymer like polythene, polypropylene, nylon and polystyrene.
13. A portion of crude oil with a particular boiling point.
14. A very long molecule formed from a string of identical chemical building blocks. Often a type of plastic.