The correct order of decreasing second ionisation enthalpy of Ti (22), V (23), Cr (24) and Mn (25) is-

Question

Aicharya · Accepted Answer

Electronic configuration of the given elements are

Mn \to 1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{5} 4 s^{2}

Cr \to 1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{5} 4 s^{1}

Ti \to 1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{2} 4 s^{2}

V \to 1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6} 3 d^{3} 4 s^{2}

In general, ionization potential ( both 1^st and 2^nd ) increases form left to right across the period due to increase in effective nuclear charge. On this basis, the second IP values should exhibit the trend :

Mn > Cr > V > Ti

But the actual observed order is :

Cr > Mn > V > Ti

Practically, only chromium is exceptional and rest others show the normal trend. This exceptional behaviour of chromium is due to the stable configuration ( 3d⁵ ) that it achieves after the loss of first electron. ,

The correct order of decreasing second ionisation enthalpy of Ti (22), V (23), Cr (24) and Mn (25) is-

Solution