Across
- 2. 2 or more elements chemically combined
- 6. pure substance made of 1 type of atom
- 8. loosely packed molecules
- 9. 2 or more substances physically combined
- 10. far apart molecules
- 11. negative charge
Down
- 1. positive charge
- 2. our unit
- 3. tightly packed molecules
- 4. neutral charge
- 5. building block of life
- 7. made of protons and neutrons