Chemistry

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Across
  1. 2. last element in the first row
  2. 5. atoms with the same atomic number but have different numbers of neutrons
  3. 6. A negatively charged particle in an atom
  4. 8. usually is reported in grams and kilograms
  5. 9. the sum of the atomic masses
  6. 10. Things that we change in an experiment
Down
  1. 1. Is made up from the atoms of two or more elements, chemically combined
  2. 3. At least two atoms, identical or not, chemically attached to each other
  3. 4. An element with the atomic number 8
  4. 7. the name of this lesson
  5. 9. unit for measuring a large number