Apentix/AP Chemistry/Unit 2: Molecular and Ionic Compound Structure and Properties/Question
AP Chemistryeasymcq1 pt

As two gaseous hydrogen atoms approach from far apart and form an H₂ bond, what happens energetically?

A.Potential energy rises steadily because approaching atoms always repel
B.Energy is absorbed, since bond breaking releases energy
C.Potential energy falls as attractions dominate, releasing energy to the surroundings
D.Nothing changes energetically until the bond suddenly snaps into place

Explanation

Core Concept

At long range the atoms barely interact. As they approach, each nucleus attracts the other's electron cloud, lowering potential energy. The decline continues until repulsions balance attractions at the bond length, where the curve reaches its minimum. Because the bonded state sits lower in energy, the difference must leave the system, usually warming the surroundings.

Correct Answer

CPotential energy falls as attractions dominate, releasing energy to the surroundings

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