Which is the correct electron configuration for sodium (na) ?

The electron configuration of a neutral sodium atom is 1 s2 2 s2 2 p6 3 s1.

In the case of sodium the one lone electron in the 3s valence shell would easily be released in order for sodium to have a filled valence shell at 2 s2 2 p6.

Therefore, the electron configuration of the sodium ion is

1 s2 2 s2 2 p6.