Before reviewing the structure of the major groups of compounds of living organisms, we need to look at the element, carbon , what a hydrocarbon is, and also study the molecules called functional groups, which bond to hydrocarbons, altering the chemical nature of the resulting compound. As you know, the chemical characteristics and bonds formed by an atom are determined by the atom's electrons. Carbon is one of the elements that forms covalent bonds to become stable. Carbon has a valence of 4 so each carbon atom makes 4 bonds . Carbon may make bonds with other carbon atoms forming chains, branching chains or rings of linked carbon atoms.
Ring compounds are common in living organisms.
Double and triple bonds alter the bonding angles and shape of the resulting molecule. The bonding of carbons to carbons is called the carbon skeleton. When carbon is not bonding to other carbon atoms, it covalently bonds to a number of other atoms, notably hydrogen, oxygen and nitrogen. In fact, the basic carbon compound is a hydrocarbon , formed from carbon and hydrogen. Hydrocarbon variations that differ only in the arrangement of atoms are called isomers.