Trigonal Shape

(Polar molecules, Non-polar molecules, etc.)

Moderators: Chem_Mod, Chem_Admin

akroberts
Posts: 24
Joined: Fri Sep 28, 2018 12:16 am

Trigonal Shape

Postby akroberts » Sun Nov 25, 2018 10:57 pm

Apart from bond angles, what is the difference between trigonal planar and trigonal pyramidal?

Stephen Sirmay 1I
Posts: 30
Joined: Fri Sep 28, 2018 12:21 am
Been upvoted: 1 time

Re: Trigonal Shape

Postby Stephen Sirmay 1I » Sun Nov 25, 2018 10:59 pm

trigonal planar has 3 regions of electron density, while trigonal pyramidal has 4. Their hybridizations are sp2 and sp3 respectively. Trigonal pyramidal has alone pair attachment.

mahika_nayak_3L
Posts: 60
Joined: Fri Sep 28, 2018 12:26 am

Re: Trigonal Shape

Postby mahika_nayak_3L » Sun Nov 25, 2018 11:02 pm

Trigonal planar exists in one plane, and you think of this shape as flat with 3 electron density regions. Trigonal pyramidal, on the other hand, is like tetrahedral, where the shape is characterized by 4 electron density regions as far apart from one another as possible in a 3D aspect. Trigonal planar bond angles are 120 and trigonal pyramidal angles are a little less than 109.5 because of electron pair repulsion.

Luc Lorain 1L
Posts: 59
Joined: Fri Sep 28, 2018 12:18 am

Re: Trigonal Shape

Postby Luc Lorain 1L » Sun Nov 25, 2018 11:24 pm

mahika_nayak_3L wrote:Trigonal planar exists in one plane, and you think of this shape as flat with 3 electron density regions. Trigonal pyramidal, on the other hand, is like tetrahedral, where the shape is characterized by 4 electron density regions as far apart from one another as possible in a 3D aspect. Trigonal planar bond angles are 120 and trigonal pyramidal angles are a little less than 109.5 because of electron pair repulsion.

This post truly does an incredible job of explaining the difference between the more 2-dimensional trigonal planar and the more 3-dimensional trigonal pyramidal shapes. Consider that the electron density correlating to the lone pair of electrons in a trigonal pyramidal molecule occupies one of the axial positions, which puts it the largest distance away from the planar (bond) electron densities. In addition, the strength of the lone pair at the axial point pushes the bonds slightly downward to maximize distance.


Return to “Determining Molecular Shape (VSEPR)”

Who is online

Users browsing this forum: No registered users and 1 guest