Across
- 2. a group of atoms bonded togethe
- 4. protons in the nucleus of an atom,
- 8. surrounding the nucleus of an atom.
- 9. mass of an atom
- 10. charge of negative electricity
Down
- 1. essential or characteristic.
- 3. positive electric charge
- 5. wo or more forms of the same element
- 6. same mass as a proton
- 7. the basic unit of a chemical element.