Question 2 Page 50 - Chapter 4 Class 9 - Structure of Atom

If K and L shells of an atom are full, then what would be the total number of electrons in the atom?  

Answer

Based on the Bohr-Bury scheme, we know that the maximum number of electrons that can be present in a particular energy shell of an atom is given by 2n 2 , where “n” is the number of energy shells.

Maximum Number of electrons in n th shell = 2n 2

For K shell, n =1

Maximum electrons = 2 x 1 2

         = 2 x 1 

         = 2 electrons

For L shell, n =2

Maximum electrons = 2 x 2 2  

         = 2 x 4 

                                 = 8 electrons

Total number of electrons = Number of electrons in K Shell + Number of electrons in L Shell

                                             = 2 + 8 

          = 10 electrons

There would be a total of 10 electrons if K and L shells are full.