Hydrogen BOnding

Hydrogen is a “bonding element” with a weak positive charge and often combines with other elements that have a negative charge. For example:     -     Water (H20) is composed of 2 hydrogen atoms and 1 oxygen atom, making water 2/3 hydrogen     -     Ammonia (NH3) is composed of 3 hydrogen atoms and 1 nitrogen atom making it 3/4 hydrogen     -     Hydrogen holds 2 strands of DNA together to form the elegant double helix, making replication of the strands possible, as they "unzip" along hydrogen bonds.

According to Dr. Helmenstine, bonding occurs because the electron is not shared evenly between a (positive) hydrogen atom and a negatively charged atom:  the hydrogen in a bond still only has 1 electron, while it takes 2 for a stable electron pair. The result is that the hydrogen atom carries a weak positive charge, so it remains attracted to atoms that still carry a negative charge.