Week 7: Use The Force, Larkin

Let's talk prefixes. What's the difference between an intermolecular force and an intramolecular force? Inter means between or among. Intra means inside or within. So an intramolecular force is one within a molecule, and an intermolecular force is between two molecules. Latin for the win!

Intermolecular forces can determine many properties of substances, such as boiling point and dissolubility. The three types of intermolecular forces are as follows: London dispersion forces, dipole-dipole forces, and hydrogen bonds. Let's take a more in-depth gander at these.

A London dispersion force occurs because there is a temporary concentration of electrons on one side of an atom which causes an artificial dipole in the molecule. This can occur in all molecules. It is also known as the induced dipole-induced dipole force. 

A similar force is the dipole-dipole force. The partial charges on the molecules create an attraction that is roughly the same strength as the London dispersion force. This does not occur in all molecules, only ones that naturally have dipoles.

But the strongest intermolecular force is... Hydrogen bonding!

Here's a nice little visual.

A hydrogen bond is an attraction that occurs between a hydrogen atom and either a fluorine, oxygen, or nitrogen atom. We tackled these in the IMF worksheets we did this week.

The other thing we did this week was learn how things dissolve (in water) by way of POGIL. Take the common example of dissolving table salt, or sodium chloride, in water. The ionic bond between sodium and chlorine is weaker than the hydrogen bonds that occur between water and the sodium and chlorine, so the ionic bond breaks apart. This successfully dissolves the salt into the water (see diagram below).

In summary, we needed to have a knowledge base about IMFs in order to move on to other subjects relating to it, like dissolving things and boiling points and such. This is important so we know what we're doing for future subjects. 

I have no jokes for this week. It was humorous in no ways. Forgive me.