Across

1. Our everyday scale of temperature.
4. Type of acid that is found in the stomach.
9. Change state from liquid to solid.
10. A chemical with pH less than 7 - turns blue litmus paper red.
12. This means containing only one substance.
16. A chemical that contains a metal, carbon and oxygen only.
17. The number of atoms "A" for every atom "B" in a chemical compound is called the ...
18. What distinguishes one substance from another - how we tell substances apart.
19. These contain only one type of atom. They are all found on the periodic table.

Down

2. A reactive alkali metal that is used in yellow street lights.
3. The smallest particle of an element.
5. How something is made up is called its ...
6. Change state from solid to liquid.
7. A measure of the thermal energy in a substance.
8. Another word for substance or stuff.
9. A recipe for a particular chemical compound.
11. Very difficult to take in the other direction.
13. How the chemical combination of substances takes place.
14. Two or more chemicals together but not chemically combined.
15. Change state from liquid to gas.