| A | B |
|---|
| nucleus | protons |
| neutrons | nucleus |
| order of elements in periodic table | atomic number |
| atomic number | number of protons |
| family | group |
| family | same # of valence electrons |
| neutral atoms | no electric charge |
| neutral atoms | # protons = # electrons |
| chloride ion | gained 1 electron |
| chloride ion | 8 electrons in the outer energy level |
| non reactive atom | 8 electrons in outer energy level |
| atoms mass # | 3 of protons and neutrons |
| atoms mass | weighted average mass of all isotopes of that element |
| family 8 | noble gases |
| noble gases | exist as single atoms only |
| elements that never combine with anything | noble gases |
| noble gases | inert |
| inert | last energy level full |
| molar mass | mass in grams of 1 mole |
| atom | Greek for unable to divide |
| periodic law | based on atomic number |
