Across
- 6. what color is the sky?
- 9. Hg as its symbol
- 10. when something remains unchanged
- 11. 2 protons and a atomic mass of 4
Down
- 1. 71 electrons
- 2. Ca as its symbol
- 3. 28 electrons
- 4. atomic mass of 223
- 5. 53 protons and a atomic mass of 127
- 7. symbol is H
- 8. make up everything
- 9. the 4th planet from the sun