Across
- 2. Large and heavy like protons, but have no electrical charge located in the nucleus.
- 6. The number of protons in an element.
- 8. An electron in the outermost energy level of an atom.
- 10. Tiny, very light particles that move outside the nucleus with a negative charge.
Down
- 1. The average mass of the naturally occurring isotopes of an element.
- 3. Equal to the number of protons plus neutrons.
- 4. An atom that carries an electrical charge.
- 5. Larger than electrons located in the nucleus with a positive charge.
- 7. Any of the possible energies an electron may have in an atom.
- 9. Two atoms with different numbers of neutrons.