Question

Answer the following questions

A) Which element of the first transition series has highest second ionisation enthalpy?

B) Which element of the first transition series has the highest third ionisation enthalpy?

C) Which element of the first transition series has lowest enthalpy of atomisation?

Answer 1

A)

$\bullet$ Copper $\left(Cu\right)$, after losing one electron forms $C{u}^{+}$ ion, and $C{u}^{+}$ ion has $3d^{10}$ electronic configuration. Due to the fully filled d-subshell, it is highly stable and it requires relatively much higher energy to remove a second electron from the filled d-orbital.

$\bullet$ Hence, copper has the highest second ionization enthalpy among first transition series elements.

B)

$\bullet$ Zinc $\left(Zn\right)$, after losing two electrons, forms $Z{n}^{2+}$ ion and $Z{n}^{2+}$ ion has $3d^{10}$ electronic configuration. Due to the fully filled d-subshell, it is highly stable and it requires high energy to remove the third electron from the filled d-orbital.

$\bullet$ Hence, zinc has the highest third ionisation enthalpy among first transition series elements.

C)

The electronic configuration of zinc is $\left[Ar\right]3d^{10}4s^2$. It has fully filled d-orbital which means there is no unpaired electron for metal-metal bond, due to which it has a weak metallic bond strength and therefore the enthalpy of atomisation is the lowest.