Across
- 4. Elements on the right side of the periodic table's staircase
- 6. Elements on the periodic table's staircase
- 8. The smallest unit of matter
- 9. Pure substance found on the periodic table
Down
- 1. An atom that has gained or lost electrons
- 2. Elements on the left side of the periodic table's staircase
- 3. An atom that has lost electrons
- 5. Different versions of an element with different numbers of neutrons
- 7. An atom that has gained electrons