University:
Eastern Kentucky University
Course:
CHE 111 | General Chemistry
Academic year:

2021
Views:

378

Pages:

2
Author:

rezancuk2j

Using VSEPR to Predict the Shapes of Molecules Electron Groups on central atom1 2 Electron-Group Shape Linear Bonds2 Lone Pairs AXmEn3 Molecular Shape Bond angles Polarity Hybrid -ization 2 0 AX2 linear 180° nonpolar4 sp 3 0 AX3 trigonal planar 120° nonpolar4 sp2 3 Appearance 180° 120° Trigonal Planar 2 1 AX2E bent <120°5 polar sp2 <120° 4 0 AX4 tetrahedral 109.5° nonpolar4 sp3 109.5° 4 3 1 AX3E trigonal pyramidal <109.5° polar sp3 <109.5° Tetrahedral 2 2 AX2E2 bent <109.5° polar sp3 <109.5° 1 “Electron groups” include bonds, lone pairs, and odd (unpaired) electrons. A multiple bond (double bond or triple bond) counts as one electron group. A multiple bond (double bond or triple bond) counts as one bond in the VSEPR model. A = central atom, X = surrounding atoms, E = lone pairs 4 Molecules with this shape are nonpolar when all of the atoms connected to the central atom are the same. If the atoms connected to the central atom are different from each other, the molecular polarity needs to be considered on a case-by-case basis. 5 Since electrons in lone pairs take up more room than electrons in covalent bonds, when lone pairs are present the bond angles are “squashed” slightly compared to the basic structure without lone pairs. 2 3 Electron Groups on central atom1 Electron-Group Shape Bonds2 Lone Pairs AXmEn3 Molecular Shape Bond angles Polarity Hybrid -ization 5 0 AX5 trigonal bipyramidal 120° eq 90° ax nonpolar4 sp3d Appearance 90° 120° ax eq eq 5 eq <90° 4 1 AX4E seesaw <120° eq <90° ax polar sp3d 3 2 AX3E2 T-shaped <90° polar sp3d 2 3 AX2E3 linear 180° nonpolar4 sp3d 6 0 AX6 octahedral 90° nonpolar4 sp3d2 <120° ax eq = equatorial ax = axial <90° Trigonal Bipyramidal 180° 90° 6 5 Octahedral 4 1 2 AX5E AX4E2 square pyramidal <90° square planar 90° polar sp3d2 <90° nonpolar4 sp3d2 90°