Oxygen reacts with fluorine to form only OF_2OF2, but sulphur which is in the same Group 16 as oxygen, reacts with fluorine to form SF_2SF2, SF_4SF4 and SF_6SF6. Why is this?

1 Answer
Jan 30, 2017

Sulfur can use its "3d"3d orbitals to form new hybrid "sp"^3"d"sp3d and "sp"^3"d"^2sp3d2 orbitals.

Explanation:

The diagram below shows the order of orbital energy levels in an atom.

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Recall that carbon can form four equivalent orbitals by promoting a "2s"2s electron to an empty "2p"2p orbital and mixing them to form new "sp"^3sp3 hybrid orbitals.

sp3
(From CHROMacademy)

In the same way, sulfur can promote its "3s"3s and "3p"3p electrons to empty "3d"3d orbitals and mixing them to form new hybrid orbitals.

The ground state electron configuration of "S"S is "[Ne] 3s"^2 "3p"^4[Ne] 3s23p4.

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Promoting a "3s"3s and a "3p"3p electron to the "3d"3d level gives the excited state shown below.

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These orbitals can be mixed to form six new hybrid "sp"^3"d"^2sp3d2 orbitals, each containing one electron.

sp3d2
(From www.alyvea.com)

These six orbitals can then overlap with the half-filled "2p"2p orbital of "F"F to form "SF"_6SF6.