RSS, Nov 2, 2011

VSEPR Practice Molecules and Ions

Here are forty-six molecules and ions that exhibit almost all the possibilities of molecular geometry, except for seven-coordinate structures. They are listed in order of numbers of electron domains - "regions of high electron density" - around the central atom(s). For the purposes of VSEPR a multiple bond is counted as a single "domain", a single bond is a "domain", and a lone pair (LP) is a "domain". There are several molecules of each basic geometry. In some molecules the preferred central atom is underlined if there might be an ambiguity in writing the Lewis structure. In this list only one molecule, C2H2, has two central atoms.

The five basic geometries of electron domains [ linear - trigonal planar - tetrahedral - trigonal bipyramidal - octahedral ] are shown in Table 9.1, p. 335, Brown&LeMay, 12th Edit. The thirteen possible molecular geometries are shown in Tables 9.2, p. 337, and 9.3, p. 340.

2 domains - domain geometry is linear, 180° bond angle (sp hybridization)

CO2, HCN, BeCl2, C2H2

3 domains - domain geometry is trigonal planar, 120° bond angles (sp2 hybridization)

NO3-, SO3, BF3, CO32-

SO2, O3, NO2-, PbCl2

4 domains - domain geometry is tetrahedral, 109.5° bond angles (sp3 hybridization)

CH4, XeO4, CCl4, SiH4, ClO4-, NH4+

NH3, PF3, H3O+, XeO3, ClO3-
H2O, OF2, H2S, SF2

5 domains - domain geometry is trigonal bipyramidal, 90°/120° bond angles (sp3d hybridization)

PCl5, SOF4, AsF5

SF4, IF4+, IO2F2-, XeO2F2

ClF3, BrF3

XeF2, I3-, IF2-

6 domains - domain geometry is octahedral, 90° bond angles (sp3d2 hybridization)


IF5, TeF5-, XeOF4

XeF4, ICl4-

Here are the same forty-six molecules and ions in random order. Write the Lewis structure and determine the domain geometry for each. Then predict the molecular geometry and find it in the above table to check.

NO3-, TeF5-, SF4, CO32-, H2S, PCl5, BF3, NH4+, AsF5, HCN, XeO2F2, ClO4-, XeF4, I3-, H3O+, ClF3, SO2, O3, NO2-, XeOF4, PF3, SF6, CH4, XeF2, XeO4, SO3, CCl4, SiH4, PbCl2, NH3, XeO3, ClO3-, H2O, OF2, SF2, CO2, SOF4, IF4+, IO2F2-, BeCl2, BrF3, IF2-, IOF5, IF5, C2H2, ICl4-

2011 by R. S. Strange