The principle that atoms tend to gain, lose or share valence electrons to achieve the same electron configurations as that of one of the noble gases.

• A. Rule of Nine
• B. Duet Rule
• C. Variations
• D. Octet Rule

Answer: (D)

All about achieving a full valence shell for stability. Most atoms become more stable when their outermost energy level is filled, and the most stable way for this to happen is to have eight electrons in that outer shell, mirroring a noble gas. That push to reach an octet drives atoms to gain, lose, or share electrons in reactions.

For example, sodium tends to lose one electron so its remaining shell has the same arrangement as neon (2 and 8). Chlorine tends to gain one to complete an outer shell of 2, 8. In covalent bonds like O2, the atoms share electrons so each atom ends up with eight in its valence shell. It’s worth noting that hydrogen and helium are a special case, because they only need two electrons to fill their first shell. Some elements can have more than eight in larger shells (expanded octets), but the general trend described here is to achieve eight electrons in the outer shell.

That’s why the principle described is the Octet Rule.