Across
- 2. two atoms with different numbers of neutrons.
- 5. an atom that carries an electrical charge.
- 6. much larger and heavier than an electron and has a positive charge.
- 7. equal to the number of protons plus neutrons.
- 10. very tiny light particles and has a negative charge.
Down
- 1. average mass of the naturally occurring isotopes of an element.
- 3. sometimes called the wave model.
- 4. an electron in the outermost energy level of an atom.
- 8. number of protons.
- 9. large and heavy like protons and has no electrical charge.