Across
- 3. a particle smaller than an atom
- 5. have a charge of +1
- 7. discovery of atoms
- 8. symbol e^-
- 9. a particle with no electric charge
Down
- 1. the basic unit of a chemical element
- 2. number every oxygen atom has 8 protons
- 4. a proton and a neutron have a mass equal to about one amu.
- 6. containing protons and neutrons
- 7. region of moving electrons