Final answer:
Electronic transitions in the Bohr model involve electrons moving between quantized energy levels, absorbing or emitting photons corresponding to the energy difference between these levels.
Step-by-step explanation:
The subject of the question is electronic transitions in atoms, specifically within the framework of the Bohr model of the atom. When an electron absorbs the required amount of energy, typically in the form of a photon, it jumps from a lower electron shell to a higher electron shell, moving farther away from the nucleus. This is referred to as the excitation of the electron. On the other hand, when an electron loses energy, it falls back to a lower electron shell, closer to the nucleus, emitting a photon of light. This photon's energy corresponds to the energy gap between the two energy levels and thus can be observed in the atomic emission spectra.
Bohr's model helps explain these transitions by suggesting that the energy levels are quantized, meaning electrons can only reside in specific shells or orbits. When an electron transitions from an excited state to the ground state, it emits electromagnetic radiation, or photons, in discrete amounts. These phenomena are a direct result of the law of conservation of energy, stating that energy cannot be created or destroyed but can be transferred from one form to another.