Question

Although B (Boron) is smaller in size as compared to Be (Berellium) but the first ionisation
enthalpy of Be (Berellium) is higher than B (Boron).

Answer 1

Question:

Although B (Boron) is smaller in size as compared to Be (Berellium) but the first ionization enthalpy of Be (Berellium) is higher than B (Boron).

Answer:

Electronic configuration of Be is $1s^22s^2$. The orbitals are filled completely and stable. Electronic configuration of B is $1s^22s^22p^1$. It's valence electron is unpaired and shielded from nucleus by s electrons, so less energy is required to remove it from the atom.

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