Across
- 3. - A family of elements with similar chemical properties
- 5. - an atom with negative charge
- 6. - an atom with positive charge
- 7. - A type of metal that reacts with other chemicals
- 9. Table - Elements can be found in it
- 12. - also known as H2O
- 13. - Reaction that releases energy by light or heat
- 15. - how many groups are there in the periodic table
- 17. - a liquid used to dissolve another substance
- 19. - an expression of chemical composition
Down
- 1. - chemical element of atomic number 7, a colorless, odorless gas
- 2. - Water and oxygen make this element
- 4. - The smallest particle of an element
- 8. - Reaction that releases cold
- 10. dioxide - also known as Co2
- 11. - materials which are considered essential to the support of biological life
- 14. - a series of elements
- 16. - simplest structural unit of a substance
- 18. - The purest of all
- 20. - also known as O2