Question

What is a noble gas electron configuration?

Answer 1

Well, helium has a closed shell, `1s^(2)` electronic configuration....

Explanation:

In order to save some time when writing the configuration of the next element, `Li, Z=3`, I could write `[He]2s^(1)`; all the reactivity is going to occur in the valence shell.

And likewise for say sulfur, `Z=16`, which builds on a neon core, we could write, `[Ne]3s^(2)3p^4`, instead of the long `1s^(2)2s^(2)2p^(6)3s^(2)3s^4`.

The square brackets represents the closed shell, inner core, inert gas electronic configuration.