Final answer:
When two atoms form a covalent bond, they share electrons, leading to a decrease in potential energy and release of energy, usually as heat. This indicates a more stable state for the molecule.
Step-by-step explanation:
When two atoms form a covalent bond, they share electrons. The process of bond formation involves both atoms approaching each other, which decreases their potential energy as their valence orbitals begin to overlap. The decrease in potential energy is due to new electrostatic attractions being established between the shared electrons and the nuclei of the bonding atoms.
The correct answer to the question is C. Energy is released when two atoms form a covalent bond. This release of energy usually occurs as heat and indicates a stable, lower-energy state for the newly formed molecule compared to the separate, individual atoms. The bond dissociation energy is the energy required to break a covalent bond and is equal to the energy released when the bond was formed.
In summary, the bond formation leads to a more stable, lower-energy configuration for the molecule. If the atoms were to continue approaching each other beyond the optimal bond length, repulsive forces would increase, causing an increase in potential energy. This optimal distance where energy is minimized is the bond length.