Final answer:
ATP is too unstable to store for more than an instant due to the repulsion between its phosphate groups. This high-energy molecule quickly dissociates into ADP + P₁, releasing energy that is used for cellular work.
Step-by-step explanation:
ATP is too unstable to store for more than an instant because it has a high-energy bond between its phosphate groups. The repulsion between these negatively charged phosphate groups makes the ATP molecule inherently unstable.
As a result, ATP quickly dissociates into ADP + P₁, releasing energy in the process. This energy is used immediately to perform work in the cell.