VSEPR calculation for propene, CH₃CH=CH₂

For propene the calculation again predicts no lone pairs on the central carbon. Here the VSEPR treatment is seen for a double bond, and note the VSEPR method works for organic species just as well as it does for inorganic molecules. The π electrons in the double bond cause that vertex to appear a little bigger than a simple σ bond and so to make room, the Me-C=CH₂ bond angle (124.8°) is a little greater than the ideal angle of 120°.

Propene, MeCH=CH₂

Lewis structure:
Central atom:	Carbon (MeCH=CH2)
Valence electrons on central atom:	4
1 Me group contributes 1 electron:	1
1 H atom contributes 1 electron	1
1 =CH2 group contributes 1 electron in a σ bond	1
Subtract one for the electron contributed by C to the π bond	-1
Total	6
Divide by 2 to give electron pairs	3
3 electron pairs:	trigonal geometry for the three shape-determining electron pairs

The geometry of propene, MeCH=CH2. You can use your mouse to manipulate the molecule in the right hand "Jmol" image.