Complete the crossword, then click on "Check" to check your answer. If you are stuck, you can click on "Hint" to get a free letter. Click on a number in the grid to see the clue or clues for that number.

						1
			2
	3
4
				5
			6
					7					8
9
10						11			12			13
14

 Check 

Across: 2. Rules that can be enforced by authority 4. The amount of chemical in a particular mass 5. Something given out by something else 6. When a chemical reacts with oxygen, releasing energy 7. The chemicals that react together in a chemical reaction 10. A measured result that appears very different from other repeat measurements. 12. A chemical made of more than one type of atom, joined together in molecules. 14. A chemical that cannot be broken down into a simpler one.

Down: 1. This is needed to meet people's present needs without spoiling the environment for the future. 3. A harmful chemical that is added by human activity to he environment 6. This speeds up a chemical reaction without being used up itself. 8. The smallest particle of an element 9. A muber of atoms joined together 11. The difference between the highest and lowest of a set of measurements 13. These are produced as a result of a chemical reaction