A chemical group consisting of a nitrogen atom bonded to two hydrogen atoms; can act as a base in solution, accepting a hydrogen ion and acquiring a charge of 1+.
A small, very toxic molecule (NH<sub>3</sub>) produced by nitrogen fixation or as a metabolic waste product of protein and nucleic acid metabolism.
A chemical group present in aldehydes and ketones and consisting of a carbon atom double-bonded to an oxygen atom.
A chemical group present in organic acids and consisting of a single carbon atom double-bonded to an oxygen atom and also bonded to a hydroxyl group.
A specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and usually involved in chemical reactions.
One of several compounds that have the same molecular formula and covalent arrangements but differ in the spatial arrangements of their atoms owing to the inflexibility of double bonds.
A chemical group consisting of an oxygen atom joined to a hydrogen atom. Molecules possessing this group are soluble in water and are called alcohols.
One of several compounds with the same molecular formula but different structures and therefore different properties. The three types of isomers are structural isomers, geometric isomers, and enantiomers.
A chemical group consisting of a carbon bonded to three hydrogen atoms. The methyl group may be attached to a carbon or to a different atom.
A chemical group consisting of a phosphorus atom bonded to four oxygen atoms; important in energy transfer.