Bent shape, VSEPR theory

Notice that the central tin atom has two shared pairs and one unshared pair of electrons. In VSEPR theory, unshared pairs occupy space around a central atom, just as shared pairs do. The two shared pairs and one unshared pair of the tin atom cause the shape of the SnCl2 molecule to be bent, as shown in Figure 17. 

Molecular shapes predicted by VSEPR theory include linear, bent, trigonal planar, tetrahedral, and trigonal pyramidal. 

In Section 4.3, we learned that the shape of a molecule is an important factor in determining the properties of the substances that it composes. For example, we learned that water would boil away at room temperature if it had a straight shape instead of a bent one. We now develop a simple model called valence shell electron pair repulsion (VSEPR) theory that allows us to predict the shapes of molecules from their Lewis structures. 

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