Atomic number of K=19 Electronic configuration [Ar]4s1 K→K++1e−;Δ1H1=419‌kJ∕mol Potassium has only one electron in outermost shell which looses easily to attain noble gas configuration. K+→K2++1e−;ΔiH2=3051‌kJ∕mol. Potassium ion has stable noble gas configuration similar to that of argon, from which the removal of electron becomes difficult resulting into increase in IE2. Potassium being a metal is electropositive in nature, which has low electron affinity resulting into low electron gain enthalpy.