Trigonal Bipyramidal

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

Moderators: Chem_Mod, Chem_Admin

205192823
Posts: 100
Joined: Wed Sep 18, 2019 12:19 am

Trigonal Bipyramidal

Postby 205192823 » Mon Nov 18, 2019 8:50 pm

In the text book it said that if the shape was trigonal bipyramidal it should have 5 bonding pairs and no lone pairs but for example 2E.3 toolbox question in the text book mentions that SF4 is trigonal bipyramidal even though it had a lone pair because it has 5 regions of electron density. So does it only consider areas of e- density when determining arrangement and considers the actual bonds when determining shape?

Brian Tangsombatvisit 1C
Posts: 119
Joined: Sat Aug 17, 2019 12:15 am

Re: Trigonal Bipyramidal

Postby Brian Tangsombatvisit 1C » Mon Nov 18, 2019 8:53 pm

Yep, electron arrangement is only determined using the # of regions of electron density, while the molecule's shape is determined using the actual number of lone pairs and bond pairs. This means that molecules with different shapes (and different formulas, ex: AX4E for SF4) can have the same electron arrangements if they have the same number of regions of electron density.

Amir Bayat
Posts: 115
Joined: Sat Sep 07, 2019 12:16 am

Re: Trigonal Bipyramidal

Postby Amir Bayat » Mon Nov 18, 2019 9:35 pm

Brian Tangsombatvisit 1L wrote:Yep, electron arrangement is only determined using the # of regions of electron density, while the molecule's shape is determined using the actual number of lone pairs and bond pairs. This means that molecules with different shapes (and different formulas, ex: AX4E for SF4) can have the same electron arrangements if they have the same number of regions of electron density.


The regions of electron density effect the shape, pushing atoms away from it due to the lone pair repulsion being greater than all the other repulsions.

Pablo 1K
Posts: 118
Joined: Sat Feb 02, 2019 12:15 am

Re: Trigonal Bipyramidal

Postby Pablo 1K » Mon Nov 18, 2019 9:37 pm

E- density influences shape of molecule but is not counted in the molecular shape naming of the molecule. Only bound atoms are.

205192823
Posts: 100
Joined: Wed Sep 18, 2019 12:19 am

Re: Trigonal Bipyramidal

Postby 205192823 » Mon Nov 18, 2019 10:04 pm

Thanks that helped cleared things up, also is the electron arrangement the same thing as electron geometry?

Abby Soriano 1J
Posts: 103
Joined: Sat Aug 24, 2019 12:16 am

Re: Trigonal Bipyramidal

Postby Abby Soriano 1J » Mon Nov 18, 2019 10:21 pm

Yes, electron arrangement can be thought of as electron geometry. Electron geometry depends on the number of regions of electron density and is supposed to help you figure out molecular geometry. Molecular geometry is where looking only at bound atoms to name molecular shape comes into play.


Return to “Determining Molecular Shape (VSEPR)”

Who is online

Users browsing this forum: No registered users and 3 guests