Water is one of the most important molecules for life, but it has one of the simplest structures! Even though it has just 2 hydrogen atoms and one oxygen atom, water makes up everything living thing.
2 hydrogen atoms are covalently bonded to the oxygen atom. Oxygen has what we call a high electronegativity. All this means is that it pulls the electrons closer to it than hydrogen. As a result, the oxygen atom has a slight negative charge and the two hydrogen atoms have slight positive charges. In the picture above, you can see that the darker blue colors represent where the electrons spend the most time.
Because of the electrical differences between the ends of the water, or polarity, water molecules can "stick" together. The partially positively-charged hydrogen atom of one water molecule is attracted to the partially negatively-charged oxygen atom of another water molecule. This fleeting attraction is called a hydrogen bond, and it explains how water can do all of the amazing things that it does. Below, are some of the cool things about water that we can see.