What term is used to label electron states that include energy level and angular momentum?

• A. Wavefunctions
• B. Atomic orbitals
• C. Spin orientations
• D. Quantum numbers

Answer: (D)

Quantum numbers are the labels used to specify an electron’s state, including its energy level and angular momentum. Each state is described by a set of discrete values: the principal quantum number n sets the energy level, the azimuthal quantum number l determines the orbital angular momentum (and orbital shape), the magnetic quantum number m_l fixes the orientation of that angular momentum in space, and the spin quantum number m_s describes the electron’s intrinsic spin. In hydrogen-like atoms, energy mainly follows n, but in multi-electron atoms the energy also depends on l due to interactions between electrons. Together, these quantum numbers uniquely identify the electron’s state, connecting energy level and angular momentum in a compact labeling system.