Bonding is essential for life in several key ways: it allows atoms to combine to form the basic building blocks of water, air, and all other substances; it is necessary for creating important foods and for preserving foods, supplying nutrients; chemical bonds must be broken during metabolism to provide energy for the body; DNA relies on hydrogen bonding to form its structure, which determines our physical characteristics; and bonding helps chemists categorize the vast number of compounds into understandable groups.