Question

explain Be has higher ∆iH1 than B​

Answer 1

Answer:

Since 2s-electrons are more strongly attracted by the nucleus than 2p-electrons, therefore, lesser amount of energy is required to knock out a 2p-electron than a 2s-electron. Consequently, ∆iH of Be is higher than that ∆iH of B.

Answer 2

(i) The electronic configuration of Be is 1s

2

2s

2

.

The electronic configuration of B is 1s

2

2s

2

2p

1

.

Be has higher Δ

i

H than B due to following reasons.

(a) The electronic configuration of Be has higher stability than the electronic configuration of B due to completely filled 2s orbital.

(b) During ionization of Be, s electron is removed.

During ionization of B, p electron is removed.

2s electron penetrates to the nucleus to greater extent than 2p electron. Thus, 2p electron is more shielded than 2s electron. The attraction of nucleus for 2s electron is higher than the attraction of nucleus for 2p electron. Thus, removal of 2s electron requires higher energy than the removal of 2p electron. Therefore, the ionization enthalpy of Be is higher than the ionization enthalpy of B.