Across
- 2. Element in all living things
- 4. Makes up most of the atmosphere
- 7. First element on periodic table
- 8. Greenish-yellow halogen gas
- 9. Most electronegative element
Down
- 1. Noble gas used in light bulbs
- 3. Essential for respiration
- 5. Noble gas used in signs
- 6. Column in the periodic table
- 7. Noble gas with 2 electrons