Question

Which of the following statements are correct?

• A. The first ionization enthalpy of phosphorus is greater than that of aluminium .
• B. The second ionization enthalpy of oxygen element is greater than that of the fluorine element.
• C. The first ionization enthalpy of aluminum is slightly greater than that of gallium.
• D. The first ionization enthalpy of B is less than that of Be.

Answer 1

Answer: (B)

The electronic configuration of

1. Oxygen-$1s^{2}2s^{2}2P^4$

2. Fluorine $1s^{2}2s^{2}2p^6$

3. Phosphorous $\left[Ne\right]3s^{2}3p^3$

4. Aluminium $\left[Ne\right]3s^{2}3p^1$

5. Gallium: $\left[Ar\right]3d^{10}4s^{2}4p^1$

6. Boron $1s^{2}2s^{2}2p^1$

7. Berylium $1s^{2}2s^2$

* Second ionization enthalpy is very high compared to fluorine due to the half-filled configuration of $O^{+}$

* The first ionization enthalpy of phosphorous is very high due to the half-filled configuration of $3p-$ orbitals.

* Electrons easy to remove in galium because they are far from nucleus compared to aluminum.

* The first ionisation enthalpy at berylium is low because it attains stable full-filled configuration of $2s^2$