Essentially, water is a molecule comprised of two hydrogen atoms and one oxygen atom. Water is a “polar molecule” because the opposing charges of the atoms attract one another and form very strong bonds through hydrogen bonding. Hydrogen bonding is especially strong and is the cause of water’s unusual properties; expansion upon freezing, vaporization upon boiling, it’s ability to take shape of whatever vessel into which it is poured, and it’s ability to loosen and dissolve other molecular bonds.

The ancient Greeks identified four elements and the great thinker Aristotle gave them their names: Earth, Fire, Air, and Water. Thales of Miletus argued that water was the most important because everything was made of water.