Across
- 2. the last ring of electrons
- 4. that holds the proton and neutron
- 5. neutral in the nucleus
- 7. positive in the nucleus
- 8. building block of the universe
- 9. 17 on the periodic table
Down
- 1. 74 on the periodic table
- 3. negative in the nucleus
- 6. 35 on the periodic table
- 8. mass the mass of an atom