A Level Physics Practice Exam

What defines an excited state for an electron?

1. An electron with no excess energy

2. An electron with some excess energy

3. An electron that is ionized

4. An electron in a transient state

The correct answer is: An electron with some excess energy

An excited state for an electron is characterized by the presence of excess energy compared to its ground state. In the ground state, an electron occupies the lowest possible energy level within an atom. When energy is absorbed—through methods such as heat, light, or electrical energy—the electron can be promoted to a higher energy level, which is what defines the excited state. This excess energy allows the electron to occupy a higher orbital, moving further away from the nucleus than it would in the ground state. The excited state is often temporary, as electrons tend to return to their lower energy states, releasing energy in the process, typically in the form of light. The other options do not accurately reflect the concept of an excited state. An electron with no excess energy is simply in its ground state, while an ionized electron refers to an electron that has been completely removed from an atom, which is a more extreme condition than simply being in an excited state. A transient state implies a temporary condition, but does not inherently indicate the presence of excess energy necessary to define an excited state. Therefore, the correct answer highlights the crucial aspect of excess energy associated with an excited state.