How is the electronic structure of sodium different from the electronic structure of chlorine?

Sodiums structure is 2, 8, 1

Chlorines is 2, 8, 7

Explanation:

They have different amounts of electrons, so they have different stuctures.

Electronic structures are written by writing the amount of electrons in each shell/energy level starting with the first one, and there are limits as well to the amount that can be in the first one, and so on.

In the first shell you can have 2

Second you can have 8

Third you can have 8

and fourth you can have 8

which is why they are written in that way.