Across
- 3. its used in batteries
- 4. most abundant element in the universe
- 7. it is made of only one type of element
- 9. you eat it when you eat eggs
- 10. helps to clean swimming pools
- 12. it has mass and volume
- 13. we need this for breathing
- 14. living things are made of it
Down
- 1. found in toothpaste
- 2. it is made of one part oxygen and two parts hydrogen
- 5. its lighter than air (and used in balloons!)
- 6. its a type of matter
- 8. there are one hundred and ________ of these in the universe (or maybe more!)
- 11. its in protein and in your muscles!