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Why does a Cs atom have lower ionization energy than a Li atom?

Answer 1

Because the valence electron of caesium is further removed from the nuclear charge as compared to that of the lithium atom.

The equation that we are examining is:

#M(g) rarrM^+(g) + e^-#

Naturally, you need to add energy. This energy DECREASES down a group and INCREASES across a period (from left to right). You should examine some values of this. The nuclear attraction increases with nuclear charge.

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Answer 2

Noah Aldrich

A Cs (Cesium) atom has lower ionization energy than a Li (Lithium) atom because Cs has a larger atomic radius and more electron shielding compared to Li. This results in weaker attraction between the outermost electron and the nucleus in Cs, making it easier to remove the outermost electron and thus requiring less energy to ionize compared to Li.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.