Oxidation Numbers Page:
Stability in Atoms:
Certain electron arrangements are more stable than others.
Octet Rule - the maximum number of electrons in an atom's outer energy level is 8.
- The most stable atoms - their outer energy level is full.
- Somewhat stable atoms - the sublevels of their outer energy level are half-filled.
- Atoms will form compounds to reach eight electrons in their outer energy level.
- Atoms with less than 4 electrons in their outer level tend to lose electrons to form compounds.
- Atoms with more than 4 electrons in their outer level tend to gain electrons to form compounds.
- A helium atom only has one energy level, which has only one sublevel (s). The 1s level can only hold two electrons. Helium has those two electrons, which makes the atom's outer energy level full. Because of this, helium is said to conform to the octet rule.