Question

Just what is stationary in a stationary state? The particle? Something else?

Short answer

As the electrons are represented by waves in quantum mechanics, the stationary states are those states of an electron in which the wave representing the electron forms a stationary wave. This results in no energy loss of electrons during the revolution.

Step-by-step solution

Concept of stationary states.

Stationary states of an electron are those states in which the electron does not experience any energy loss while revolving around the nucleus. In this state, the angular momentum of the electron remains conserved.

Stationary wave

In quantum mechanics, the electron is not considered a particle but is represented by a wave function. The stationary state of an electron is that state in which the electron, revolving in an orbit, forms a standing wave or a stationary wave. In this state, there is no loss of energy experienced by the electrons.

Conclusion

The stationary states are those states in which the wave representing an electron remains stationary. Thus, no energy loss is experienced by the electron.