VSEPR Geometry


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Manuel Gonzalez_1L
Posts: 17
Joined: Fri Sep 25, 2015 3:00 am

VSEPR Geometry

Postby Manuel Gonzalez_1L » Fri Oct 30, 2015 3:50 pm

For the VSEPR Geometry what is the difference between the EPG and MG?

anne_kleinaitis_3B
Posts: 13
Joined: Fri Sep 25, 2015 3:00 am

Re: VSEPR Geometry

Postby anne_kleinaitis_3B » Fri Oct 30, 2015 4:20 pm

MG: molecular geometry. EPG: electron pair geometry. Molecular geometry deals with the atoms attached to a central atom. Electron pair geometry deals with the atoms and the lone pairs attached to the central atom. Both types are considered zones of electron density, and both types create geometric shapes. For example: methane is CH4, and it is a tetrahedron with C as the central atom and 4 Hs connected to it. This is molecular geometry because there are only atoms attached to the central atom. EPG example: Water is H20. Its molecular geometry is bent, but when you consider the 2 lone electron pairs on O, the 2 electron pairs and the 2 H atoms all repel each other to create a tetrahedron. Thus, the difference is that sometimes just atoms create geometry (MG), whereas other times electrons and atoms create geometry (EPG).

Vanessa A 3F
Posts: 29
Joined: Fri Sep 25, 2015 3:00 am

Re: VSEPR Geometry

Postby Vanessa A 3F » Sat Oct 31, 2015 3:36 pm

There are 6 electron pair geometries to remember, and from them, you can derive the molecular geometry
2 electron dense regions?
EPG is linear
3 electron dense regions?
EPG is trigonal planar
4?
EPG is tetrahedral
5?
EPG is trigonal bipyramid
6?
EPG is octahedral

After you decide what a molecule's EPG is, then you can find its molecular shape based on the shapes that come from each EPG and taking lone pairs into account

Image


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