Question

What is the electron configuration for the element sodium?

Answer 1

The electronic configuration of Sodium (atomic number is 11) is-

`1s^2 2s^2 2p^6 3s^1`

Note:-
For writing the electronic configuration of elements, the Aufbau Principle is used. In Aufbau Principle, the electrons are filled according to the increasing energy level of orbitals.

According to the Aufbau Principle, first the atomic number of element is determined (like here oxygen has atomic number 8) and then the electrons are filled in this order-
1s 2s 2p 3s 3p 4s 3d and so on...

In 's' orbital, maximum number of filling the electrons is 2.
In 'p' orbital, maximum number of filling the electrons is 6.
In 'd' orbital, maximum number of filling the electrons is 10.
In 'f' orbital, maximum number of filling the electrons is 14.

For example-
i) The electronic configuration of Chlorine (atomic number is 17) is-

`1s^2 2s^2 2p^6 3s^2 3p^5`

ii) The electronic configuration of Titanium (atomic number is 22) is-

`1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^2`