Write in the answers, the highlighted boxes will spell out a number

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Across
  1. 4. __________ table - contains all the elements ordered by atomic number(8 letters)
  2. 6. a neutral subatomic particle (7 letters)
  3. 7. where the protons and neutrons are located in an atom (7 letters)
Down
  1. 1. a negatively charged particle found around the nucleus (8 letters)
  2. 2. a positively charged subatomic particle (6 letters)
  3. 3. where electrons are found in the atom
  4. 5. type of bond formed between a metal and a non-metal (5 letters)
  5. 8. type of bond formed between 2 non-metals (8 letters)