The Basic Bond of a Water Molecule
A hydrogen atom is made up of one positively charged proton that is orbited by one negatively charged electron. An oxygen atom has eight protons (positive subatomic particle) and eight neutrons (neutral subatomic particles) in its nucleus and is surrounded by eight electrons (negative subatomic particles). Because of the structure of oxygen, it has two spots open in its electron cloud, which are quickly filled when a hydrogen atom is exposed to oxygen. When hydrogen bonds with oxygen, the electrons that have bonded are formed into five pairs of ten electrons - one pair forms the oxygen atom's inner electron cloud, two pairs form the oxygen atom's outer electron cloud, and the two remaining pairs form the O-H bonds, which create the polar molecule H2O.
The Importance of Hydrogen in Water
Water must be a polar molecule in order to maintain surface tension, a specific boiling point, and the ability to buoy floating objects, etc. Of course, none of this would be possible without the hydrogen bonds found in water molecules. Because of hydrogen bonds, water has the ability to buoy objects above its surface, and some bugs even have the ability to walk on water (e.g. the water glider). Water is also known as a universal solvent, which would not be possible without the use of hydrogen bonding.