Question

The correct values of ionization enthalpies (in KJ ${mol}^{-1}$) of Si, P, S and Cl respectively are:

• A. 786, 1012, 999, 1256
• B. 1012, 786, 999, 1256
• C. 786, 1012, 1256, 999
• D. 786, 999, 1012, 1256

Answer 1

The correct option is A

786, 1012, 999, 1256

The ionisation energy tends to increase as one moves from left to right across a period(with exceptions), because the atomic size decreases due to an increase in the nuclear charge and thus, more energy is required to remove the electron(s).Phosphorous has more ionisation energy than sulphur due to stable half filled electronic configuration.

So, the correct order of ionisation enthalpy is Si < P > S < Cl