Molecular shape electron-group arrangements

Valence-Shell Electron-Pair Repulsion (VSEPR) Theory and Molecular Shape Electron-Group Arrangements and Molecular Shapes... 

In the following ExpressLab, you will make models of the five electron-group arrangements, and measure their bond angles. Afterwards, you will consider some of the variations in molecular shapes that can occur... 

Table 4.2 Common Molecular Shapes and Their Electron Group Arrangements... 

Follow the four-step procedure that helps to predict molecular shape. Use Table 4.2 for names of the electron-group arrangements and molecular shapes. 

In what cases is the name of the molecular shape the same as the name of the electron group arrangement ... 

Figure 10.3 Electron-group repulsions and the five basic molecular shapes. A, As an analogy for electron-group arrangements, two to six attached balloons form five geometric orientations such that each balloon occupies as much space as possible. B, Mutually repelling...

Figure 10.4 The single molecular shape of the linear electron-group arrangement. The key (bottom) for A, X, and E also refers to Figures 10.5, 10.6, 10.8, and 10.9.

Describe the five electron-group arrangements and associated molecular shapes, predict molecular shapes from Lewis structures, and explain deviations from ideal bond angles ( 10.2) (SPs 10.6-10.8) (EPs 10.25-10.49)... 

Name all the molecular shapes that have a tetrahedral electron-group arrangement. 

Determine the electron-group arrangement, molecular shape, and ideal bond angle(s) for each of the following ... 

We postulate the presence of a certain type of hybrid orbital after we observe the molecular shape. As we discuss the five common types of hybridization, notice that the spatial orientation of each type of hybrid orbital corresponds with one of the five common electron-group arrangements predicted by VSEPR theory. 

To account for other molecular shapes within a given electron-group arrangement, we postulate that one or more of the hybrid orbitals contains lone pairs. In ozone (O3), for example, the central O is sp hybridized and a lone pair fills one of its three sp orbitals, so ozone has a bent molecular shape. 

Figure 11.5 shows the bonding in other molecular shapes with the tetrahedral electron-group arrangement. The trigonal pyramidal shape of NH3 arises when a lone pair fills one of the four sp orbitals of N, and the bent shape of H2O arises when lone pairs fill two of the sp orbitals of O. 

VB theory explains that a covalent bond forms when two atomic orbitals overlap and two electrons with paired (opposite) spins occupy the overlapped region. Orbital hybridization allows us to explain how atomic orbitals mix and change their characteristics during bonding. Based on the observed molecular shape (and the related electron-group arrangement), we postulate the type of hybrid orbital needed. 

Electron-Group Arrangements arxl Molecular Shapes... 

Figure 10.5 The two molecular shapes of the trigonal planar electron-group arrangement.

Figure 10.6 The three molecular shapes of the tetrahedral electron-group arrangement.

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