Across
- 1. number of electrons
- 3. Bohr model of atom
- 5. neutral particles
- 8. discovered the electron
- 10. Chemical reaction is a rearrangement of atoms
- 11. negatively charged protons
- 12. discovered first neutron
Down
- 2. Positively charged particles
- 4. number of electron shells
- 6. gold foil experiment
- 7. Unit of a Chemical Element
- 9. substance consisting of atoms which have the same number of protons