[AL chem]Ca o既atomic radius 點解大過Zn??

The electronic configurations:

Ca: 1s2 2s2 2p6 3s2 3p6 4s2

Zn: 1s2 2s2 2p6 3s2 3p6 3d10 4s2

Consider the screening effect. From Ca to Zn, the increase in screening effect is due to filling in 10 more 3d electrons.
It is known that electrons in inner shells (n = 1, 2 and 3) of small n give stronger screening effects than electrons in inner shells of large n. Also, inner electrons give screening effect in order of: s > p > d. Therefore, the 10 3d-electrons have weaker screening effect than all other electrons in the inner shells.

From Ca to Zn, the nuclear charge is increased by 10, but the increase in screening effect due to filling in 10 more d-electrons is small as discussed above. Therefore, the electrons in the outermost 4s shells of Zn are thus more strongly held by the nuclei than those of Ca. This leads to the fact that Zn has a smaller atomic radius than Ca.
=

以我學了一個月 Electronic Configuration 既知識, 3d orbital 的能量較 4s 為高, 所以 3d orbital 是在 4s orbital 外面, 因此進入 3d orbital 入面既 electrons 會在 4s orbital 既 electrons 既外面.

當 electrons 進入 3d orbital, electrons 係入緊同一個 shell, 所以 the outermost electrons are poorly screened. 而 proton 上升, 所以 effective nuclear charge 增加, 吸力大左, 導致 atomic radius 短了.

2008-11-02 21:23:16 補充：
咁Zn 甩電子,會甩3d orbital o既electron 先????

正確 ^^