An electron in an atom is likely to move from one energy level to another when it gains or loses energy.
Explanation:
The change in an electron’s position with respect to energy levels is termed as Atomic electron transition. In spite of having similar charge and mass, the energy level of any electron in an atom, surrounding the nucleus, differs depending on its orbital position from the nucleus.
Electrons positioned nearest to the atomic nucleus carry least energy. To move an electron from its original ground state energy level to a higher level; energize the atom and it will excite the electrons thus making it move from its lower energy stable state to an unstable state with higher energy level. Releasing energy of an atom decreases the energy level of its excited electrons, de-energizing it and thus stabilizing the atom.