Oxygen reacts with fluorine to form only #OF_2#, but sulphur which is in the same Group 16 as oxygen, reacts with fluorine to form #SF_2#, #SF_4# and #SF_6#. Why is this?

1 Answer
Jan 30, 2017

Answer:

Sulfur can use its #"3d"# orbitals to form new hybrid #"sp"^3"d"# and #"sp"^3"d"^2# 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"# electron to an empty #"2p"# orbital and mixing them to form new #"sp"^3# hybrid orbitals.

sp3
(From CHROMacademy)

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

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

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Promoting a #"3s"# and a #"3p"# electron to the #"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"^2# orbitals, each containing one electron.

sp3d2
(From www.alyvea.com)

These six orbitals can then overlap with the half-filled #"2p"# orbital of #"F"# to form #"SF"_6#.