Important People in Chemistry History

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Across
  1. 3. Russian scientist who organized the first periodic table (by atomic mass)
  2. 4. organized the elements by atomic number(number of protons)
  3. 7. number of elements on the table
  4. 8. also known as families (18 of them)
  5. 9. number of periods on the table
Down
  1. 1. (partially)indicated by group number
  2. 2. studied chemical bonding
  3. 5. found the orbital
  4. 6. elements in the same group have __ properties