10.2: VSEPR
- Page ID
- 96591
Introduction:
This part of the review goes over the use of Valence Shell Electron Repulsion Theory (VSEPR) to determine molecular geometries. You should review your general chemistry 1 notes. If they are not available, go to
section 8.6: Molecular Geometries
Worksheets
Handout \(\PageIndex{1}\) : Overview of Structures:
http://chemwiki.ucdavis.edu/@api/deki/files/60818/VESPR_Geometry_Handout.pdf T
The above 3 page handout gives the basic VESPR geometries of table 2.1 (below), along with the hybrid orbitals (review section
Handout \(\PageIndex{2}\) : VSEPR Worksheet
http://chemwiki.ucdavis.edu/@api/deki/files/61155/vsepr2_Worksheet.pdf
The above handout is a continuation of the exercise in section 10.1 Lewis Dot Structures. You should fill out that handout first, and then use it while filling out this handout.
Molecular Geometries
Table 1 shows some examples of geometries with a central atom \(A\) is bonded to two or more \(X\) atoms. As indicated in several of the geometries below, non-bonding electrons can strongly influence the molecular geometry of the molecule. Note: "E" represent lone pairs of electrons
6 | 5 | 4 | 3 | 2 |
---|---|---|---|---|
AX6 octahedral |
AX5 trigonal bipyramidal |
AX4 tetrahedral |
AX3 trigonal planar |
AX2 linear |
1 lone pair of electrons | ||||
AX5E square pyramidal |
AX4E distorted tetrahedron |
AX3E pyramidal |
AX2E nonlinear |
AXE linear |
2 lone pairs of electrons | ||||
AX4E2 square planar |
AX3E2 T-shaped |
AX2E2 bent |
These structures can generally be predicted, when A is a nonmetal, using the "valence-shell electron-pair repulsion model (VSEPR) discussed in the next section. This image table was borrowed from Paul Groves LibreText, and the rotating molecules were created by Robyn Rindge.
Exercise \(\PageIndex{1}\)
What is the molecular geometry of triiodide (I3-), which has two bonding and 3 lone pairs? (It is not in the above table)
- Answer
-
Linear