| Answer | Crossword Clue |
|---|---|
| TWO | Atomic number of helium |
| TEN | Atomic number of neon |
| ONE | Atomic number of hydrogen |
| SEVEN | Atomic number of nitrogen |
| ATE | Homophone for the atomic number of oxygen |
| TIN | Its atomic number is half of fermium's |
| ISOTOPES | Forms of elements having same atomic number. |
| ISOTOPE | One of several elements, having the same atomic number. |
