A Level Physics Practice Exam

What does it mean for an electron to exist at discrete energy levels?

1. It can attain any energy level

2. It can only occupy certain specific energy levels

3. It fluctuates between energy levels

4. It absorbs and releases energy continuously

The correct answer is: It can only occupy certain specific energy levels

When we say that an electron exists at discrete energy levels, it means that the electron can only occupy specific energy levels within an atom, and cannot exist in between these levels. This quantization of energy levels arises from the principles of quantum mechanics, which dictate how electrons behave in atomic structures. In an atom, electrons occupy distinct orbitals, and each of these orbitals corresponds to a particular energy level. These energy levels are determined by factors such as the type of atom and its electron configuration. The fact that electrons cannot have energies between these defined levels is a key feature of quantum mechanics. For instance, when an electron transitions from a higher energy level to a lower one, it releases energy in a quantized amount, typically in the form of a photon of light. This concept also leads to various phenomena in atomic physics, such as the emission and absorption spectra of elements, where specific wavelengths of light are released or absorbed corresponding to the differences in energy between these discrete levels. Understanding this framework allows physicists to predict and explain the behavior of electrons in different atomic and molecular environments.