Final answer:
Electrons in an atom can only exist at discrete energy levels and not in between them due to the quantization of energy. They must absorb or emit energy to move from one energy level to another. These transitions can cause the release or absorption of energy, often observed as light.
Step-by-step explanation:
Within an atom, electrons exist in zones known as energy levels, which can be visualized as the steps of a ladder in the Bohr model. The quantization of energy in an atom means that electrons may occupy specific energy levels, corresponding to certain principal quantum numbers denoted by 'n', with each level having a distinct and quantifiable energy value. However, electrons cannot exist between these levels; they must either absorb or release energy to jump from one level to another. This process is often depicted as a staircase where, in a similar fashion, one cannot stand between the steps.
The principal quantum number 'n' indicates the energy level of an electron, with higher values of 'n' corresponding to higher energy levels. When an electron transitions between levels, it either absorbs or emits energy in quantized amounts. These transitions are responsible for various phenomena, such as the emission of light in fireworks when electrons jump to higher levels and then fall back down, releasing energy.
The second and third energy levels of an atom can accommodate up to eight electrons. Here, the arrangement of electrons within orbitals follows a specific order, ensuring that each orbital is singly occupied before any pairing occurs. This principle helps determine the distribution of electrons in these levels and plays a crucial role in chemical reactions and bonding.