Specify the properties of atomic orbitals and the properties of electrons in orbitals.

• A. Quantum numbers
• B. Principle quantum number
• C. Orbital
• D. Line-emission spectrum

Answer: (A)

Quantum numbers are used to specify the properties of atomic orbitals and the electrons in orbitals. Each electron is described by four numbers: n, l, m_l, and m_s. The principal quantum number n sets the energy level and size of the orbital. The azimuthal quantum number l (ranging from 0 to n−1) defines the subshell and the orbital shape. The magnetic quantum number m_l determines the orbital’s orientation in space. The spin quantum number m_s (±1/2) describes the electron’s intrinsic spin. Together, these four values uniquely describe the electron’s state, including its energy, the shape and orientation of its orbital, and its spin properties—key factors that influence chemical behavior and bonding. The principal quantum number is only one piece of this full description. An orbital identifies a region in space, but it does not by itself encode all these properties. The line-emission spectrum relates to transitions between energy levels, not the static properties of electrons in orbitals.