Final answer:
To break the phosphate bond in ATP, a hydrolysis reaction is needed in which a water molecule is added, resulting in the formation of ADP, a free phosphate group, and the release of free energy. This reaction is exergonic due to the relief of repulsion between the negatively charged phosphate groups.
Step-by-step explanation:
To break the phosphate bond in ATP, a water molecule is needed to be added in a process known as hydrolysis. The bond that links the beta and gamma phosphate groups is called a phosphoanhydride bond, and its breaking releases a significant amount of energy. Therefore, this reaction involves adding water to ATP which results in the formation of ADP (adenosine diphosphate), a free phosphate group (Pi), and the release of energy.
The hydrolysis reaction can be represented as: ATP + H₂O → ADP + Pi + free energy. This reaction is exergonic because it releases more energy than it consumes, which is primarily due to the relief of repulsion between the negatively charged phosphate groups in ATP.