Across
- 3. Essential gas for respiration (6 letters)
- 5. Lightest and most abundant element in the universe (8 letters)
- 6. Element that forms the basis for organic life (6 letters)
Down
- 1. Noble gas used in brightly colored signs (4 letters)
- 2. Metal used to make steel, symbol is Fe (4 letters)
- 4. Precious metal with the symbol Au (4 letters)