Variation of PE as two H atoms approach each other

The variation of potential energy (PE) as two hydrogen atoms approach each other is influenced by the interplay between attractive and repulsive forces. As the atoms move closer together, the potential energy undergoes significant changes, which can be understood in terms of the interaction between their electron clouds and the electrostatic forces between the nuclei and electrons.

When two hydrogen atoms are far apart, the electron clouds of each atom experience only weak attractive forces. At this point, the potential energy is relatively low since there is little interaction between the atoms. As the atoms start to approach each other, the electron clouds of the two atoms begin to overlap.

The overlapping electron clouds create an attractive force between the atoms known as the London dispersion force. This force arises due to the temporary fluctuations in electron distribution and induces a slight attraction between the atoms. As the atoms get closer, the potential energy decreases further as the attractive forces become more significant.

However, as the atoms continue to approach each other, the repulsive forces between their positively charged nuclei become more pronounced. These repulsive forces arise due to the electrostatic repulsion between the like charges of the protons in the nuclei. The potential energy starts to increase rapidly as the repulsion outweighs the attraction.

At a certain point, known as the equilibrium bond length, the attractive and repulsive forces balance each other, resulting in the lowest potential energy between the two hydrogen atoms. This equilibrium bond length corresponds to the most stable configuration of the hydrogen molecule, where the potential energy is at its minimum.

If the atoms are brought even closer together than the equilibrium bond length, the repulsive forces dominate, causing the potential energy to increase sharply. This indicates an unfavorable arrangement, and the atoms will experience a strong repulsion.

The variation of potential energy as two hydrogen atoms approach each other can be visualized using a potential energy diagram. The diagram shows the change in potential energy as a function of the distance between the atoms, highlighting the regions of attraction, equilibrium, and repulsion.

In summary, the variation of potential energy as two hydrogen atoms approach each other is determined by the balance between attractive and repulsive forces. Initially, there is a weak attraction due to electron cloud overlap, leading to a decrease in potential energy. However, as the atoms get closer, the repulsive forces between their nuclei become dominant, causing the potential energy to increase. At the equilibrium bond length, the potential energy reaches its minimum, indicating a stable configuration. Beyond this point, further approach results in a rapid increase in potential energy due to strong repulsion. Understanding the variation of potential energy provides insights into the stability and bonding behavior of hydrogen molecules.