Across
- 4. a pure substance made of one type of atom
- 7. a substance formed from two or more elements chemically combined
- 8. process where substances change into new substances
- 9. substance formed in a chemical reaction
- 13. a negatively charged particle surrounding the nucleus
- 14. the dense center of an atom
Down
- 1. substances physically combined but not chemically bonded
- 2. starting substance in a chemical reaction
- 3. the smallest unit of an element
- 5. positively charged particle in the nucleus
- 6. chart that organizes all known elements
- 10. two or more atoms bonded together
- 11. a neutral particle in the nucleus
- 12. force that holds atoms together