Write the electronic configuration of any one pair of isotopes and isobars.

 

Answer

  • Isotopes are elements having the same atomic number but different mass numbers.

Example, and

 

                                                                    

Mass number = 35                                                 Mass number = 37

Atomic number = 17                                               Atomic number = 17             

Number of electrons = atomic number = 17          Number of electrons = atomic number = 17

Electronic configuration - 2, 8, 7                             Electronic configuration - 2, 8, 7

K Shell - 2 electrons                                             K Shell - 2 electrons

L Shell - 8 electrons                                              L Shell - 8 electrons                                                          

M Shell - 7 electrons                                              M Shell - 7 electrons 

                          

Since isotopes have the same atomic number, their electronic configuration is the same.




  • Isobars are elements having different atomic numbers but same mass numbers.

 

For example: and 

 

                                                                     

Mass number = 40                                                 Mass number = 40

Atomic number = 20                                              Atomic number = 18            

Number of electrons = atomic number = 20          Number of electrons = atomic number = 18

Electronic configuration - 2, 8, 8, 2                      Electronic configuration - 2, 8, 8

K Shell - 2 electrons                                            K Shell - 2 electrons

L Shell - 8 electrons                                             L Shell - 8 electrons                                                          

M Shell - 8 electrons                                            M Shell - 8 electrons

N Shell - 2 electrons

 

Since isobars have different atomic numbers, their electronic configuration is different.

  1. Class 9
  2. Chapter 4 Class 9 - Structure of Atom (Term 2)

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CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo