Structure of Matter

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Across
  1. 2. length or portion of time.
  2. 6. a table of the chemical elements
  3. 9. a thing composed of two or more separate elements
  4. 10. a column in the periodic table
Down
  1. 1. same mass as a proton but without an electric charge
  2. 3. a particle with a charge of negative electricity
  3. 4. the number of protons in the nucleus of an atom
  4. 5. a part or aspect of something abstract
  5. 6. a stable subatomic particle
  6. 7. smallest unit of matter
  7. 8. a group of atoms bonded together