Question

IE2 for alkali metals shows a jump whereas IE3 for alkaline earth metals shows a jump.Explain.

Answer 1

It requires high energy to remove the electrons from a fully filled orbital.

In case of alkali metals..

Electronic configuration is ns² (n+1)s¹

So, it requires less amount of energy to remove the 1st electron from half filled (n+1)s¹ orbital .

After the removal of 1st electron the electronic configuration becomes ns² (n+1)s^0.

Now the 2nd electron is to be removed from fully filled ns² orbital which require larger amount of energy.

In case of alkali earth metals..

Electronic configuration is ns² (n+1)s²

So, it requires less amount of energy to remove the 1st electron from fully filled (n+1)s² orbital .

After the removal of 1st electron the electronic configuration becomes ns² (n+1)s^1.

Now the 2nd electron is to be removed from half filled (n+1)s¹ orbital.

After the removal of 2nd electron the electronic configuration becomes ns² (n+1)s^1.

Now the 3rd electron is to be removed from fully filled ns² orbital which require larger amount of energy.

Hence,

IE₂ for alkali metals shows a jump in values whereas IE₃ for alkaline earth metals shows a jump.