Example:

Sodium with 11 electrons 1s²2s²2p⁶3s¹ loses one electron to form a Na⁺ cation

with the electron configuration 1s²2s²2p⁶ which is [Ne] is neon core.

Example:

The combination of F and Cl gives FCl where both atoms have a complete octet.

Example:

Calcium with 20 electronshas an electron configuration [Ar]4s^2. It loses two electrons to form a Ca²⁺ cation

with the electron configuration for 18 electrons 1s²2s²2p⁶3s²3p⁶ which is an [Ar] core.

Example:

Oxygen 1s²2s²2p⁴ gains two electrons to form an oxide O^2- anion

with the electron configuration 1s²2s²2p⁶ which is a [Ne] core.

Example:

Chlorine 1s²2s²2p⁶3s²3p⁵ gains one electron to form chloride Cl^1- anion

with the electron configuration 1s²2s²2p⁶3s²3p⁶ an [Ar] core

Octet rule exceptions:

The octet rule really applies to a limited number of elements in row 2 of the periodic table; C, N, O and F.  

Exceptions to the octet rule occur regularly for row 3 and greater. These elements with open d subshells like phosphorus and sulfur do not always follow the rule. Examples of octet rule "violations" are SF₆ and PCl₅.Use the octet rule to predict the number of covalent bonds normally formed by phosphorus, P. Click for answer