system
Given the following post, respond as if you're commenting on Reddit:
human
Why are water molecules curved?

Why don't the charges of the hydrogen repel each other and hold the molecule in a straight line?
gpt
The geometry of a water molecule is determined by the outermost electrons around the oxygen. You have two electrons in each of the bonds between oxygen and water, but you also have two pairs of electrons that oxygen holds onto all on its own. If we just had the two electron groups from the bonds you would be right, the hydrogens would be 180 degrees straight across from each other in order to give the electrons as much space as possible, but since we also have those two extra pairs of electrons from the oxygen, we have to make space for those two. This ends up meaning that there is only 109.5 degrees between each of those electron groups. Hope that helps!