Water is a very versatile molecule. As you probably know, it essential to life on Earth. Its molecular formula is H2O, which means it consists of two hydrogen atoms and one oxygen atom. Water is classified as a polar molecule because it is unequally charged. This imbalance of charge allows water molecules to link via Hydrogen bonds. Below is an example of how water molecules interact with one another.
These hydrogen bonds contribute to some of water’s awesome properties. For instance, H-bonds directly influence water’s ability to float when frozen. When water reaches zero degrees Celsius, it undergoes a phase change from liquid to solid. In their solid state, water molecules form a crystal lattice. (For reference, see the photo below.) This crystal lattice takes up more space than liquid water, but weighs the same. So, because of its crystal lattice, solid water is less dense than liquid water, which means it floats. In lakes, rivers, and other bodies of fresh water, ice insulates marine life from the cold. If ice didn’t float, large amounts of marine life would die every winter.
Another one of water’s interesting qualities is its ability to dissolve many compounds. Because water is a polar molecule, it dissolves other polar molecules. As a rule of thumb, “like dissolves like.” This means that polar solvents dissolve polar solutes and non-polar solvents dissolve non-polar solutes. Water dissolves other polar substances in a very interesting way. The positively charged regions of water surround the negatively charged regions of the solute while the negatively charged regions of water surround the positively charged regions of the solute. This creates what is called a hydration shell around the solute. Water’s unique capabilities as a solvent make many chemical reactions possible. These chemical reactions are very important and ultimately allow for us to survive.