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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: propene.gif
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.

A VSEPR tutorial on the WWW

VSEPR tutorial on the WWW, URL:
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Document served: Monday 23rd October, 2017