periodic table

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Across
  1. 2. is a group of elements
  2. 3. mass is an SI unit
  3. 4. The smallest particle of an element
  4. 5. positively charged subatomic particle in the nucleus of an atom
Down
  1. 1. A subatomic particle that has no electric charge.
  2. 4. An anion is a negatively charged particle.