Lone Pairs

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

Moderators: Chem_Mod, Chem_Admin

timothy_ho_4B
Posts: 61
Joined: Fri Sep 28, 2018 12:29 am

Lone Pairs

Postby timothy_ho_4B » Sun Nov 11, 2018 3:22 pm

Do the lone pairs of the atoms not at the center of the molecule affect the shape at all? Don't the lone pairs also contribute to electron
repulsion and thus shape as well?

Michelle Fu 1H
Posts: 35
Joined: Fri Sep 28, 2018 12:19 am

Re: Lone Pairs

Postby Michelle Fu 1H » Sun Nov 11, 2018 3:55 pm

After some quick googling (as I don't think we have covered this subject in class yet) it seems that unpaired electrons do have a effect on the VSEPR models in that they alter the angle. For example, if there are two bonding groups and zero unpaired, the geometry is linear, but if there is 1 lone pair then the shape is transformed into bent.

For more reference, this is where I got my information:
http://intro.chem.okstate.edu/1314F00/L ... VSEPR.html

305113590
Posts: 66
Joined: Fri Sep 28, 2018 12:28 am

Re: Lone Pairs

Postby 305113590 » Sun Nov 11, 2018 3:58 pm

Yes it does because lone pairs want to be closer to the nucleus in comparison to a bonding pair. When this happens, the lone pairs take up more space due to the repulsion between each other.
Hence, the geometric shape is important because it shows the shape that minimizes the repulsion between electrons of that atom

Bianca Barcelo 4I
Posts: 74
Joined: Fri Sep 28, 2018 12:17 am
Been upvoted: 1 time

Re: Lone Pairs

Postby Bianca Barcelo 4I » Sun Nov 11, 2018 4:00 pm

When creating the VSPER model, do the bonds or lone pairs take take precedence over the other?

Michael_Navarro_1H
Posts: 29
Joined: Fri Sep 28, 2018 12:17 am

Re: Lone Pairs

Postby Michael_Navarro_1H » Sun Nov 11, 2018 5:08 pm

The lone electron pairs have a greater effect on the molecule shape. Looking at H2O for example, we see that the lone pairs on the Oxygen atom changes the shape of water from a theoretical linear geometry to the bent configuration.

Alma Carrera 3C
Posts: 33
Joined: Fri Apr 06, 2018 11:02 am

Re: Lone Pairs

Postby Alma Carrera 3C » Sun Nov 11, 2018 6:06 pm

So would H2O have a trigonal planar shape or a tetrahedral shape?

RoopshaChatterjee 1G
Posts: 30
Joined: Fri Sep 28, 2018 12:17 am

Re: Lone Pairs

Postby RoopshaChatterjee 1G » Sun Nov 11, 2018 6:17 pm

I believe H2O would be tetrahedral shape because there are 2 bonding pairs and 2 lone pairs resulting in a bent angle of 104.5 degrees.

Shivangi_2J
Posts: 65
Joined: Fri Sep 28, 2018 12:15 am

Re: Lone Pairs

Postby Shivangi_2J » Sun Nov 11, 2018 6:19 pm

only the lone pairs around the central atom affect the shape of the molecule (For example the lone pairs of chlorine on CCL4 would not affect the molecules shape)


Return to “Determining Molecular Shape (VSEPR)”

Who is online

Users browsing this forum: No registered users and 1 guest