Question

Which of the following represents the correct order of increasing first ionization enthalpy for Ca, Ba, Si, P and Ar? 1)Ba < Ca < Si < P < Ar 2)Ba < Ca < P < Si < Ar 3)Ca < Ba < Si < P < Ar 4)Ar < P < Si < Ba < Ca

Answer 1

Explanation:

Order of first ionisation energy is Sc> Na > K > Rb. Due to poor shielding effect, removal of one electron from 4s orbital is difficult as compared to 3s-orbital. Order of first ionisation energy is Sc> Na > K > Rb.