Which quantum number can indicate the energy of an electron in an atom?

The principal quantum number (n) directly indicates the energy level of an electron in an atom. It is a key determinant of the electron's distance from the nucleus and the energy associated with that position. As n increases, the energy of the electron also increases, reflecting that electrons in higher principal energy levels are generally farther from the nucleus, resulting in a higher potential energy.

The other quantum numbers serve different purposes. The orbital quantum number (l) provides information about the shape of the orbital, influencing the sub-levels within a principal energy level but does not directly indicate energy. The magnetic quantum number (m) describes the orientation of the orbital in space and also does not correlate with energy levels. The spin quantum number (s) represents the intrinsic spin of the electron but does not affect the energy of the orbital itself; instead, it is more about the orientation of the electron's spin. Thus, understanding that the principal quantum number is crucial for determining an electron's energy in an atom is fundamental in quantum mechanics and atomic theory.