Problem: What is the value of the bond angles in SiCl 4?

We’re being asked to identify the bond angle in SiCl₄. Since we don’t know the Lewis structure for SiCl₄, we need to do the following steps:

Step 1: Determine the central atom in this molecule.

Step 2: Calculate the total number of valence electrons present.

Step 3: Draw the Lewis structure for the molecule.

Step 4: Determine the number of electron groups around the indicated atom.

Step 5: Determine the electron geometry and bond angle using this:

Electron Regions          Electronic Geometry          Bond Angles

2                                      linear                                    180˚

3                                      trigonal planar                      120˚

4                                      tetrahedral                            109.5˚

5                                      trigonal bipyramidal              90˚, 120˚, and 180˚

6                                      octahedral                            90˚ and 180˚