Across
- 2. amount of material in matter
- 3. atoms with same atomic number
- 7. average of atomic masses
- 8. what atoms are made of
- 11. atoms of 2 different elements in fixed proportion
- 12. has mass & no electrical charge
- 16. no (very little) mass and negative
- 17. protons + neutrons
- 18. shell outermost energy level of atom
Down
- 1. different # of neutrons than protons
- 4. atoms held by shared electrons
- 5. formed between atoms
- 6. unstable isotopes
- 9. number of protons in an atom
- 10. location of protons and neutrons
- 13. has mass & positive electrical charge
- 14. smallest stable units of matter
- 15. shell location of electrons
- 17. takes up space & has mass