Across
- 4. the number of protons in the nucleus of an atom
- 6. a set of chemical elements in the same row of the periodic table
- 7. a table of chemical elements arranged in order of atomic number
- 8. the mass of an atom of a chemical element
- 9. an atom without a charge
Down
- 1. a negatively charged atom
- 2. a set of chemical elements in the same vertical column of the periodic table
- 3. the chemical elements in group 18 of the periodic table
- 5. an abbreviation of the name of each chemical element discovered and expressed in the periodic table
- 6. a positively charged atom