Energy Levels of an Ideal Gas Molecule

For the ideal gas, we know that attractions and repulsions between molecules 

When energy is added to the ideal gas as heat or work, the energy is added to the molecules of the gas as internal energy, and a change dU in internal energy results such that 

This energy increase can take different forms. It can be added as translational kinetic energy to speed up the movement to and fro of the molecules it can be added to the rotations of the molecules to get them to spin faster it can be added to increase the amplitude of the vibrational oscillations of the molecules and it can be added to excite electrons to higher energy states in the atoms or molecules. Other forms of internal energy are also possible, but the above are the most common. 

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