Linear Shape

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

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Sohee Park 3E
Posts: 11
Joined: Fri Sep 25, 2015 3:00 am

Linear Shape

Postby Sohee Park 3E » Mon Oct 26, 2015 5:40 pm

Hello,

Problem 1 says: Below are ball-and-stick models of two molecules. In each case, indicate whether there must be, may be, or cannot be one or more lone pairs of electrons on the central atom. Part b: 180 degrees. The answer key says "May have lone pairs." Why is this? I thought that lone pairs affect the shape of every molecule, including the linear ones (ex. bent)

Ronald Yang 2F
Posts: 86
Joined: Fri Sep 25, 2015 3:00 am

Re: Linear Shape

Postby Ronald Yang 2F » Mon Oct 26, 2015 7:12 pm

Sohee Park 3E wrote:I thought that lone pairs affect the shape of every molecule, including the linear ones (ex. bent)
You are correct; lone pairs do affect the shape of a molecule. So, for a molecule to be 180 degrees, it can have no lone pairs, such as BeCl2. But, a molecule can also have lone pairs and still be 180 degrees. A good example is XeF2. The electron geometry of this molecule is trigonal bipyramidal, since xenon has two atoms attached to it and three lone pairs. In this case, the three lone pairs do affect the shape in that they cancel out, as they are equilaterally oriented. Thus, the three lone pairs actually help make the molecule linear, which is why the answer key says "May have lone pairs."

Camille 4I
Posts: 57
Joined: Sat Aug 24, 2019 12:18 am

Re: Linear Shape

Postby Camille 4I » Sun Nov 10, 2019 10:15 pm

If an atom has three lone pairs, wouldn't two of the lone pairs have stronger repulsion than the single lone pair on the other side?


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