Today in biochemistry, we learned about the hydrophobic effect. This is when nonpolar molucules are exposed to an aqueous environment and they bunch together. The process is driven by entropy. Molecules in nature perfer to be disordered, therefore the nonpolar molecules bunch together to minimize interactions with the polar water molecules. When polar and nonpolar molecules interact, the polar molecules form a ridgid shell around the nonpolar molecules. The polar molecules are in a tight formation and not free to move around. The polar water molecules can form dipole-dipole interactions with other polar water molecules because water has permanent, partical charges. The nonpolar molecules form van der waal interactions between themselves. This process can be seen in salad dressing when the bottle is shaken. The bubbles of oil that are formed disperse but reappear after a few minutes.
Comments
Very clear paragraph
The paragraph explains the concept clear but it lacks some flow. The first few sentences seems too short and simple. I would be easier to read if you connected the first few sentences into a longer one so that the reader does not have to stop for every period. Also, I think you should capitalize van der Waal interaction because it is a name of a person.
Small edit
In the sentence where you talk about polar water molecules forming dipole-dipole interactions you say polar water molecules twice. I think you can omit the second polar and just keep it as water.
we
In scientific writing, if you refer to "we" or "us", it is a reference to the authors of a multi-authored paper. You can't claim allegiance to other groups in scientific writing: you can't use "we" or "us" to refer to students in the class or at the University. Or refer to "us" as human beings or inhabitants of the Earth.
suggestion
In the first sentence, I would avoid using the word "we" because it's unformal in scientific paragraph. Instead I suugest replacing it with "the students".