# What's the most stable electron configuration?

The most stable electron configuration is that of a noble gas, due to the fact that its valence shell is filled. For helium, that means two valence electrons (a duet) in the $\text{1s}$ sublevel, and for the rest it means eight valence electrons (an octet) in the outermost $\text{s}$ and $\text{p}$ sublevels.