An Overview of Bent Molecular Geometry
Hi, welcome to this video tutorial on bent molecules. The term bent molecule refers to the physical arrangement of atoms within a molecule. For example, H2O is a bent molecule, but what makes a molecule appear this way?
Well, let’s take a look. First, it’s important to understand why certain molecules are what we call linear. Let’s look at carbon dioxide as an example. Here we see that carbon is the central atom and has 2 oxygen. The carbon has no lone pairs of electrons.
A lone pair is where the electrons are not shared with any other atom. That’s important for understanding bent molecule structure because a molecule always has a central atom, with 2 bonded atoms, and 1 to 2 lone pairs of electrons.
Let’s look at H2O as an example of a bent molecule now. You may be wondering, “Why in the world would H2O be bent if CO2 is not?” They both have a central atom, both have two other atoms bonded to them, so why not a linear shape?
Well, let’s take a look at the molecular structure here. At the center, we have 1 oxygen atom that is bonded to 2 hydrogen atoms, but what we don’t see here are 2 pairs of electrons that are lone–they’re not bonded to anything–and because of that they don’t get represented in the photo.
There are actually 2 pairs of unbonded electrons up here, and we know that electrons have a negative charge and repel other electrons. They then settle into whatever shape has the least resistance, kind of like how water always flows to the lowest point.
In the case of bent molecules, that shape is always between 109.5 and 104 degrees. Bent molecules occur most frequently in group 16 elements because they have 6 electrons in their outer shell, allowing for 2 bonds and 2 lone pairs. Okay, so let’s review.
First, the term bent molecule refers to the geometric shape that bonded atoms have taken. Second, each bent molecule must have a central atom with 2 bonded atoms. Third, every bent molecule must have 1 or 2 lone pairs of electrons. I hope that helps. Thanks for watching this video tutorial.