Why is a noble gas different from other elements?

May 1, 2014

Each of these elements have completed s and p orbitals of the highest eery level, ${s}^{2} {p}^{6}$. These elements all complete the Rule of Octet (Helium - Rule of Duet).

Helium - He $1 {s}^{2}$
Neon - Ne $1 {s}^{2} 2 {s}^{2} 2 {p}^{6}$
Argon - Ar $1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{6}$
Krypton - Kr $\left[A r\right] 3 {d}^{10} 4 {s}^{2} 4 {p}^{6}$
Xenon - Xe $\left[K r\right] 4 {d}^{10} 5 {s}^{2} 5 {p}^{6}$
Radon - Rn $\left[X e\right] 5 {d}^{10} 6 {s}^{2} 6 {p}^{6}$

Since each of these elements have completed outer valence shells they do not seek to lose or gain electrons to become stable. These elements therefore do not readily bond with other elements and therefore are considered inert or unreactive.