ATP is a nucleoside triphosphate molecule, composed of a ribose sugar, a nitrogenous base (adenine) and three serially bonded phosphate groups. The energy from ATP is stored between the second and third phosphate group. A ribose sugar is at the center of the ATP molecule, and attached to that is the adenine molecule (forming adenosine). The other side of ribose is attached to three phosphate groups, hence the name of the molecule adenosine triphosphate. The building blocks of ATP are carbon, oxygen, nitrogen, hydrogen, and phosphorus. The three phosphate groups are connected together by two high-energy bonds known as phosphoanhydride bonds.