Chemistry

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Across
  1. 2. What type of test is used to identify metal ions?
  2. 3. What must occur between particles in order for a reaction to occur?
  3. 8. What type of energy is needed to start a reaction?
  4. 9. Substances that only contain one thing are considered what?
  5. 10. How reactive are Group 1 metals?
Down
  1. 1. Isotopes have a different number of..?
  2. 4. Ions with opposite charges form what type of bond?
  3. 5. What is formed when halogens react with alkali metals?
  4. 6. Iron reacts with oxygen and what else to form rust?
  5. 7. Biological catalysts.