Question

Compare Second ionisation energy of the following ( With justification) :
1) B&Be
2) F & Ne
3) O & N
4) Be+ & B+

Answer 1

Second Ionization energy refers to energy required to  remove an electron from the gaseous uni positive ion.
Usually second ionization energy will be greater than first ionization energy.

1. B & Be

IE1 of B is less than Be.
E.C of B is 1s²2s²2p¹
Be is 1s²2s²
Be has stable full configuration and penetrating power of 2s1 electrons in Be greater than 2p electron of B.
Therefore IE1 of Be> IE1 of B
After the removal of electron from B it attains stable configuration-1s²2s²
 hence IE2 of B >IE2 of Be

2)F and Ne:

F- electronic configuration -1s² 2s²2p⁵
Ne - electronic configuration-1s²2s²2p⁶
As neon is having stable configuration, hence removing an electron is very difficult.
Hence, IE1 of Ne> IE1 of F
As Neon is most stable and unreactive .
Hence IE2 of Ne> IE2 of F

3) O & N
Oxygen has less stable electronic configuration than nitrogen. NITROGEN has stable half filled electronic configuration.
 Therefore, IE of O<IE1 of N
After the removal of an electron, oxygen acquires stable [He]2s²2p³half filled configuration.
Hence IE2 of O>IE2 of N

4)Be+ and B+
Here the comparison is between Ions
electronic configuration Of Be+= 1s²2s¹
electronic configuration of B+ =1s²2s²
We can see B+ is having more stable electronic configuration.
Hence IE1 of B+ > IE1 of Be+
After removal of electron
Be++ electronic configuration- 1s²
B++ --- electronic configuration- 1s²2s¹
we can see Be++ acquires stable electronic configuration . Hence removing an electron becomes more difficult.
Hence IE2 of Be+ > B+