ionization enthalpy of zinc

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2009-01-01 1:49 am

Why the first ionization enthalpy of zinc is unexpectedly high?

I know that zinc has a fully filled d sub-shell, but the first ionization should be the removal of electron in 4S obitial. It should be no need to concern about the d obitial.

回答 (1)

Uncle Michael

2009-01-01 2:10 am

✔ 最佳答案

The first ionization enthalpy of zinc (Zn: 1s2 2s2 2p6 3s2 3p6 3d10 4s2) is unexpectedly high. This is because:

(1) The 3d subshell is completely filled with ten 3d electrons. The screening effect of the 3d electrons is weaker than that s or p electrons. Due to the weak screening effect, the two 4s electrons in the outermost shell experience a large nuclear attraction. Therefore, more energy is needed to remove a 4s electron.

(2) The 4s subshell is completely filled, and exhibits extra stability. Therefore, more energy is needed to remove a 4s electron in order to break its completely filled structure of 4s subshell.
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