Why does Zn2+ have 18 electrons in its outer shell? Does it have to follow the octet rule?

2 Answers
Oscar L.
Dec 18, 2017

It doesn't.

Explanation:

Generally, the octet rule spies to elements in groups 13 through 18, which react with jyst s and p electrons. And it does not apply, at least not in straightforward fashion, for the heavier elements even in these groups.

Meave60 ยท Truong-Son N.
Dec 18, 2017

The valence shell of main-group elements is typically composed of the outermost (highest energy) s and p sublevels, which hold a total of 8 valence electrons. An octet refers to having 8 electrons in the valence shell, but transition metals are another story.

Explanation:

The valence shell of a main-group element is typically made up of the outermost (highest energy) s and p sublevels.

The ground state electron configuration of a neutral Zn atom is:

1s22s22p63s23p64s23d10

The electron configuration of a Zn2+ cation is:

1s22s22p63s23p63d10

The removal of the 4s2 electrons leaves 18 electrons in the 3rd energy level, which should not be surprising. The 3d orbitals allow for violation of the octet "rule", as in PF5, SF6, etc.

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