Chemistry puzzle

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Across
  1. 3. a chemical reaction in which two or more simple substances combine to form a new, more complex substance
  2. 5. a chemical substance that is present at the start of a chemical reaction
  3. 6. a pure substance that cannot be broken down into simpler substances by physical or chemical means
  4. 8. a multiplier or factor that measures some property
  5. 9. a substance made up of atoms of two or more different elements joined by chemical bonds
  6. 11. when substances interact and change into new substances
Down
  1. 1. A number in a chemical formula that tells the number of atoms in a molecule or the ratio of elements in a compound
  2. 2. a process during which chemical bonds between atoms are broken and new ones are formed. Producing one or more different substances
  3. 4. in any physical change or chemical reaction, mass is conversed; mass can be neither created nor destroyed
  4. 7. a group of atoms bonded together
  5. 10. a chemical substance formed as a result of a chemical reaction