Across
- 2. ______ number, the horizontal rows
- 5. atoms having the same proton but differ in the no. of neutrons
- 6. has a symbol A
- 8. subatomic particle with positive charge
- 11. a type of reaction that gives out heat energy
- 12. not a pure substance
- 13. a pure substance formed by a chemical reaction
- 14. belong to group 7
Down
- 1. ________ molecules ;ex. H2, N2, Cl2
- 3. the lightest subatomic particles
- 4. has a symbol of Na
- 5. charged particles
- 7. mass __________ is a device used to identify the isotopes and their natural abundance
- 9. found inside the nucleus that have neutral charge
- 10. ______ number , a vertical column of the Periodic table