Across
- 1. A horizontal row in the periodic table.
- 4. A count of the number of protons in the nucleus.
- 8. The mass of an element's atoms.
- 9. A small, negatively charged subatomic particle found outside the nucleus.
- 10. A positive charged subatomic particle in the nucleus.
Down
- 2. Any material that is made up of only one type of atom.
- 3. A chart in which all known elements are listed in order by atomic number.
- 5. The dense, positively charged center of an atom.
- 6. A neutral subatomic particle in the atomic
- 7. A vertical column in the periodic table.