Question

The first ionisation energy of oxygen is less than that of nitrogen. Which of the following is the correct reason for this observation?

Solution

Correct option is

Greater interelectron repulsion between two electrons in the same p-orbital counter balances the increase in effective nuclear charge on moving from nitrogen to oxygen  

 

The electronic configuration of nitrogen is

                     7N = 1s2, 2s2, 2p3

                                                          

Due to the presence of half-filled p-orbitals a large amount of energy is required to remove an electron from nitrogen. Hence, first ionisation energy of nitrogen is greater than that of oxygen.

The electronic configuration of oxygen is  

                     8O = 1s2, 2p2, 2p4

                                                               

The other reason for the greater IP of nitrogen is that in oxygen, there is a greater inter electronic repulsions between the electrons present in the samep-orbital which counter balance the increase in effective nuclear charge from nitrogen to oxygen. 

SIMILAR QUESTIONS

Q1

Which of the following sequence correctly represents the decreasing acidic nature of oxides?

Q2

Which of the following pairs of species have nearly same size?

Q3

The set representing the correct order of ionic radius is

Q4

The pair of elements having approximately equal ionisation potential is

Q5

Which is not the correct order for the stated property?

Q6

The correct order of ionisation energy of C, N, O, F is

Q7

The electron affinity values (in kg mol–1) of three halogens XY and Z are respectively –349, –333 and –325. Then XY and Z respectively, are

Q8

Which of the following has the highest second ionisation energy?

Q9

The electronic configuration of the element with maximum electron affinity is

Q10

The charge/size ratio of a cation determines its polarizing power. Which one of the following sequences represents the increasing order of the polarizing power of the cationic species, K+, Ca2+, Mg2+, Be2+