Why does potassium has lower ionization enthalpy than Ar?

Ionization enthalpy is defined as the energy required to remove electrons from the outermost orbit or valence shell of one mole of gaseous atoms. There are two different approaches you can take to understand ionization enthalpy: 1. read more

Ionization enthalpy is defined as amount of energy required to remove the outermost electron from a gaseous isolated atom. So atomic number of potassium is 19 and it has configuration of [Ar] 4s1. read more

This is why potassium has higher ionization enthalpy than argon. I have assumed knowledge of electronic configurations of argon and potassium. Feel free to point out any mistakes that i might have made. read more

ANSWER: The shielding effect describes the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell. Li has 2 orbits and Na has 3 orbits, therefore the attraction in outermost electron of Na is less than that of Li, hence Na has higher shielding effect. 3. read more

Hence heat of ionization of Potassium is very low. On the other hand Ar already has a completely filled 3rd orbit making exceptionally stable. Hence it refrains from losing or gaining electrons. Thus, Ionization Enthalpy of Potassium is lower than that of Ar. read more

Potassium(K) has one more electron than Argon, which is in the next shell. Hence, Potassium can lose this electron comparatively easily to attain the configuration of Argon which is a stable electronic configuration. This is why potassium has higher ionization enthalpy than argon. read more

ANSWER: Sodium has three orbits and potassium has four orbits. Lesser the distance of orbits from nucleus, higher the energy is required to remove the outermost electron, and vice versa. Therefore, more energy is required to remove electron from sodium than from potassium. Hence, the ionization energy of sodium is higher. 2. read more