Summary:
- The octet rule states that atoms tend to form compounds in ways that give them eight valence electrons and thus the electron configuration of a noble gas.
- An exception to an octet of electrons is in the case of the first noble gas, helium, which only has two valence electrons.
- Atoms of metals tend to lose all of their valence electrons, which leaves them with an octet from the next lowest principal energy level.
- Atoms of non