What rule describes the tendency of atoms to prefer having 8 electrons in their valence shell?

The octet rule describes the tendency of atoms to prefer having eight electrons in their valence shell to achieve a more stable electron configuration. This stability mimics that of the noble gases, which have full outer electron shells. Atoms will often undergo bonding—either by sharing, losing, or gaining electrons—to reach this octet configuration. This is particularly important in the formation of covalent and ionic bonds.

Atoms that do not have eight electrons in their valence shell will seek to react with other atoms to fill their outer shell, often leading to the formation of stable compounds. This rule is a cornerstone of understanding chemical bonding and molecular structure in human biology and chemistry overall.