Chemical reactions

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Across
  1. 2. How many electrons in the outer shell of elements in group 3
  2. 4. Atomic mass is the number of Protons AND ______
  3. 8. Protons and Neutrons are in this part of the atom
  4. 10. These are in shells outside the nucleus
  5. 11. A type of reaction where a substance is broken down
  6. 13. Atoms cannot be created or _________
  7. 15. Element, Group 2 period 3
  8. 17. Atomic number is also the number of what part of the nucleus
Down
  1. 1. Left hand side of the arrow
  2. 3. In a chemical reaction we say the atoms are
  3. 5. Group 0 is also known as
  4. 6. Atomic number 13
  5. 7. Group 7 is also known as
  6. 9. Right hand side of the arrow
  7. 12. The British spelling, atomic number 16
  8. 14. A reaction that gives out heat
  9. 16. Group 1 elements are known as