Across
- 4. An atom that carries an electrical charge.
- 5. Two atoms with differnet numbers of neutrons.
- 7. Tiny, very light particles that move around the outside of the nucles.
- 8. An electron in the outermost energy level of an atom.
- 9. Large and heavy have no electrical charge.
- 10. Large and heavy located in the nucleus of the atom.
Down
- 1. number of protons.
- 2. equal to the number of protons plus neutrons.
- 3. Any of the possible energies an electron may have in an atom.
- 6. Average mass of the naturally occurring isotopes of an element.