Across
- 3. six
- 7. a charged chemical species composed of two or more atoms covalently bonded
- 8. one
- 9. nine
- 12. bond between two nonmetals
- 13. chemical substance composed of multiple elements
- 15. a substance that cannot be broken down into simpler substances
- 16. four
- 17. eight
Down
- 1. seven
- 2. a positively charged ion
- 4. electrons in the outer shell of an atom
- 5. ten
- 6. bond between a metal and a nonmetal
- 7. five
- 10. a negatively charged ion
- 11. the basic unit of a chemical element
- 14. two
- 18. three