The following represents the electronic configuration and its associated term symbol for the ground state neutral gaseous atom. The configuration associated with sodium in its compounds is not necessarily the same.
Ground state electron configuration: [Ne].3s1
Shell structure: 2.8.1
The bright yellow transition of Na at 589 nm, labelled "D" in the solar spectrum, is actually a pair of lines, that is, a "doublet". Spectrograph generated using , courtesy of Cavendish Instruments Ltd.
The image below is a schematic representation of the shell structure of sodium - not what the atom of sodium "looks like".