Why is the first ionization energy of potassium greater than that of cesium?
Saturday, August 29th, 2009 at
9:55 PM
I know the basics of the trends but I don’t understand why they change. I need to know what periodicity principles ( like effective nuclear charge, shielding, and valence electrons) cause the first ionization energy to change.
Filed under: Potassium Questions
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Ionization energy is the enery it takes to lose an electron. In K, the electrons are relatively near the positive nucleus. Cs is much bigger. This disperse electron cloud means that the highest energy electron in Cs feels the positive attraction of the nucleus less than the highest energy electron in K (which is less shielded).