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TSR Wiki > Study Help > Subjects and Revision > Revision Notes > Chemistry > Ionization Energy and Electron Affinity 2

Why is the second ionization energy of potassium so much greater than the first?

In the 2nd IE, the electron is being removed from a 1+ ion whereas in the 1st IE it is removed from a neutral atom therefore there is a stronger attraction from the nucleus on the electron being removed from the 1+ ion. The 2nd electron is also closer to the nucleus and there is more shielding from the nucleus on the 1st electron than the 2nd.

Why do successive ionization energies increase?

Each time an electron is removed, the next has to be removed from an ion with a stronger + charge.

Explain the relative magnitude of the 1st and 2nd electron affinities of oxygen

Energy is released when the 1st electron is added to a neutral atom therefore 1st electron affinity is exothermic. But the 2nd electron affinity is endothermic because energy needs to be put in to overcome the repulsion between the electron and the negative atom.

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