When Does a Molecule Have a Bent Shape?
Bent Molecular Shape
Bent Molecular Shape
A molecular has a bent shape when it meets two guidelines. So the first guideline is it must have the formula AX2 where A represents the central atom and X represents the other atom. So there’s going to be one central atom and two of the other atom.
The second guideline is the number of lone pairs must be one or two. Now, if you’re unfamiliar with what a lone pair is, it is a pair of valence electrons that is not being bonded to or being shared with another atom. In other words, it’s just being used by one atom. So, if an atom meets both of these guidelines, then it has a bent molecular shape.
So, we’re going to go ahead and take a look at a couple of molecules to see if they have a bent molecular shape.
So, the first is water, which looks like this H2O. Now, right off the bat you may be thinking this does not have the same form as AX2, but you still have one central atom and you still have two of the other atoms so it has the right shape. So if we were to draw this, we would have the central atom up here, oxygen, then we would have the two hydrogen atoms out like this. And here oxygen has two lone pairs, so since H2O meets both of these guidelines, then it does have a bent molecular shape. And the bond angle is always going to be less than 109.5 degrees.
So the second molecule we’re going to take a look at is tin chloride. And so right off the bat you see here that this does meet this formula. And so tin right here is the central atom and then you have the two other atoms here. So then if we’re going to draw this, we’re going to put tin up here and then we’ll draw it like this. And tin here has one lone pair, so it meets both of the guidelines, so it has a bent molecular shape, so the bond angle is going to be less than 109.5 degrees.
So just remember that in order for a molecule to have a bent molecular shape, the molecule must have the formula AX2, with A being the central atom and X being the other atom, and the number of lone pairs must be one or two.
Provided by: Mometrix Test Preparation
Last updated: 05/28/2018