Question

Which one of the following is a correct electronic configuration of sodium? ​

• A. 2,8
• B. 8,2,1
• C. 2,1,8
• D. 2,8,1

Answer 1

The correct option is D 2,8,1

The number of electrons that can be accommodated in a shell is given by the Bohr-Bury formula $2n^2$, where n is the shell number. ​

For K shell, $n=1$, L shell, $n=2$, etc..​

According to this formula, K-shell can hold a maximum of 2 electrons, L-shell can hold a maximum of 8 electrons and M-shell can hold a maximum of 18 electrons, etc.​

The atomic number of sodium is 11. It has 11 electrons. The correct electronic configuration of sodium will be 2, 8, 1.​

Hence, option D is correct.​