What configuration elements of sodium

The electron configuration of Sodium (Na) : 1s²2s²2p⁶3s¹

Sodium is an element with the symbol Na and has the atomic number 11. It is located in Group 1 (alkaline) and period 3

atomic number=number of electron=11

In an atom there are levels of energy in the shell and sub shell  

This energy level is expressed in the form of electron configurations.  

Charging electrons in the sub shell uses the following sequence:  

1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁶, 5s², 4d¹⁰, 5p⁶, 6s², etc.  

So the electron configuration for Natrium ( with 11 electrons) :

1s²2s²2p⁶3s¹ or we can write [Ne] 3s¹