What does the octet rule state about outer-shell electrons?

• A. Atoms with 2 electrons in their outer shell are most stable
• B. Atoms with 8 electrons in their outer shell are most stable
• C. Atoms with 10 electrons in their outer shell are most stable
• D. Outer shell electron count does not affect stability

Answer: (B)

Atoms tend to be most stable when they have eight electrons in their outermost shell. This eight-electron, noble-gas-like configuration lowers energy and drives bonding, so atoms gain, lose, or share electrons to reach that full valence shell. Hydrogen and helium are the exceptions, achieving stability with just two electrons in their outer shell. So the statement that outer shells prefer eight electrons best reflects the common pattern described by the octet rule.