Which of the following statement(s) is/are consistent with the Bohr theory of the atom (and no others)? (1) An electron can remain in a particular orbit as long as it continuously absorbs radiation of a definite frequency. (2) The lowest energy orbits are those closest to the nucleus. (3) All electrons can jump from the \(K\) shell to the \(M\) shell by emitting radiation of a definite frequency. (a) \(1,2,3\) (b) 2 only (c) 3 only (d) 1,2

In the Bohr model of the atom, the notion of stationary states is pivotal. Envision an atom as a miniature solar system where electrons orbit the nucleus, akin to how planets revolve around the Sun. Yet, unlike the solar system, electrons can only inhabit certain orbits without releasing or absorbing energy—these are known as stationary states.

These special orbits are fundamentally stable, meaning that as long as an electron is in a stationary state, it won't spiral into the nucleus or radiate energy away. This concept was a radical departure from classical physics, which couldn't explain why electrons didn't simply crash into the nucleus. Bohr's theory brought stability to the picture, showing that an atom's structure is not a frenzy of energy exchange, but rather a collection of specific, well-ordered states.

You can think of quantized energy levels as distinct steps on an energy staircase within an atom. The foundational rule in Bohr's atomic model is that electrons can only possess certain discrete amounts of energy—no more, no fewer. Each step on this theoretical staircase corresponds to a specific orbit or energy level in which electrons can reside.

The term 'quantized' is essential here; it signifies that these energy values are not a continuous spectrum but a set of fixed quantities. Just as you can't stand between the steps of a staircase, electrons can't have energies that lie between these quantized levels. This explanation resolved numerous perplexities about atomic spectra that classical theories failed to address—why, for example, atoms emit or absorb light at only certain frequencies...

An exciting event occurs when electrons jump between these quantized orbits, known as electron transitions. Imagine an electron gaining a precise amount of energy from a photon; this energy influx allows the electron to climb up to a higher energy level or orbit. Conversely, when an electron falls to a lower energy orbit, it releases energy in the form of a photon with a frequency directly proportionate to the energy difference of the transition.

These transitions are like dance steps that electrons perform, but they can only hit certain marks—the quantized orbits we've discussed. The frequency of the emitted or absorbed radiation during these transitions gives us the atomic spectra, a characteristic set of lines like fingerprints for every element, providing a powerful tool for understanding the subatomic world.