There are two phosphate groups in adenosine diphosphate, or ADP. The formation of adenosine diphosphate occurs through the hydrolysis of adenosine triphosphate, or ATP, in which three phosphate groups are reduced to two. The chemical formula for ADP is C10H15N5O10P2.
ATP is composed of three components: adenine, a sugar molecule called ribose and three phosphate groups. The conversion of ATP to ADP is important because it provides the energy needed by all biological organisms. The conversion occurs when ATP reacts with water to produce ADP, free energy and inorganic phosphate. This chemical reaction is also reversible.
ADP is an organic compound that has a molecular weight of 427 grams per mole.