Sulfur tetrafluoride Lewis structure

The difference between equatorial and axial positions determines the arrangement of bonding pairs and lone pairs around an atom with a steric number of 5. An example is provided by sulfur tetrafluoride, a colorless gas that has industrial uses as a potent fluorinating agent. The Lewis structure of SFq shows four S—F bonds and one lone pair of electrons on the sulfur atom. These five pairs of electrons are distributed in a trigonal bipyramid around the sulfur atom. 

A fluoride of composition SF4 is formed when fluorine diluted with nitrogen is passed over a film of sulfur at — 75°C in the absence of oxygen and moisture. Write the Lewis structure of sulfur tetrafluoride. 

To predict the shape of a sulfur tetrafluoride molecule, SF4, we first write its Lewis structure (29a) (recall Example 2.7). The molecule is an example of an AX4E species, with four atoms on the central S atom and one lone pair. According to Fig. 3.4, the five electron pairs adopt a trigonal bipyramidal arrangement. The lone pair occupies an equatorial location. The energy is lowered further if the atoms move away from the lone pair (29b). This shape (resembling a slightly bent seesaw) is the one found experimentally. 

Use Lewis structures to predict the molecular polarities for sulfur difluoride, sulfur tetrafluoride, and sulfur hexafluoride. 

It is also possible to encounter a molecule that seems to have too many valence electrons. When that happens, we expand the valence shell of the central atom. Consider the Lewis structure for sulfur tetrafluoride SF4, for example, which contains thirty-four valence electrons. 

Practice Exercise Write the Lewis structure of sulfur tetrafluoride (SF4). 

AB4E, Ns = 5, one lone pair sulfur tetrafluoride (SF4). The Lewis structure of SF4 is... 

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