What is the term for an energy level representing the distance of an electron from the nucleus of an atom?

• A. Electron shell
• B. Valence
• C. Nucleus distance
• D. Orbital

Answer: (A)

In atoms, electrons occupy energy levels that correspond to how far they are from the nucleus. These levels are called electron shells, each associated with a principal quantum number that roughly indicates the average distance from the nucleus. As you move to higher shells, the electrons sit farther away and are less tightly bound. An orbital is a specific region within a shell where an electron is likely to be found, and there can be several orbitals in the same shell. Valence refers to the outermost electrons involved in bonding, not to a distance from the nucleus. “Nucleus distance” isn’t a standard term. So the term that best describes the energy level representing distance from the nucleus is electron shell.