Summarize the essential features of the Lewis octet rule. The octet rule applies mainly to the second period elements. Explain.

The Lewis octet rule is a rule in chemistry stating that atoms tend to bond so they each have eight electrons in their valence shell, thus achieving electron-configuration stability like a noble gas. Its main features are its applicability mostly to nonmetals, its goal for atoms to achieve noble gas-like stability, the exceptions where the rule doesn't apply, and its use to predict chemical bonding patterns. The second period elements, from lithium to neon, have only 2s and 2p orbitals available in their valence shells and these can maximally accommodate only eight electrons. Hence, these elements tend to gain, lose, or share electrons to comply with the octet rule, illustrating why it mainly applies to them.