Across
- 1. Average mass of an element.
- 2. An atom that carries an electrical charge
- 4. any of the possible energies an electron may have in an atom.
- 6. an electron in the outermost energy level of an atom.
- 7. number of protons in a neutral atom.
- 9. Particle with a positive charge.
Down
- 1. equal to the number of protons plus neutrons.
- 3. Particle with a negative charge.
- 5. Particle without a electrical charge.
- 8. Two atoms with different numbers of neutrons