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.

NCERT Class IX
Sciences - Exemplar Problems

Chapter 4. Structure of the Atom

Answer 1

Hi there !

Sodium:-
Atomic no = 11
No: of protons = 11
No: of electrons = 11
Mass no: = 23

K SHELL MUST HAVE 2 ELECTRONS
L SHELL MUST HAVE  8 ELECTRONS MAXIMUM
etc ...

Electronic configuration = 2 , 8 , 1

Answer 2

Heya,

Atomic number of sodium = 11

Number of protons = Number of electrons = 11

According to the rule of doublet the first shell has 2 electrons and according to rule of octet the second shell has 8 eight electrons and the other electron in last shell.

Therefore it's electronic configuration will be 2, 8,1

Thus, option D is correct.

Hope it helps u........