A student uses the particulate model shown below to represent the individual steps of bond cleavage and bond formation during the gas-phase synthesis of ammonia.

\[ \text{N}_2(g) + 3\text{ H}_2(g) \rightarrow 2\text{ NH}_3(g) \]

Stage 1 represents the initial reactant mixture, Stage 2 represents the transition to isolated gaseous atoms, and Stage 3 represents the product mixture. Which of the following best describes the energy changes associated with the transitions from Stage 1 to Stage 2 and from Stage 2 to Stage 3?