Which quantum number indicates the shape or type of subshell in which an electron is found?

Which quantum number indicates the shape or type of subshell in which an electron is found?

• A. Magnetic Quantum Number
• B. Spin Quantum Number
• C. Subshell Quantum Number
• D. Principal Quantum Number

Answer: (C)

The number that sets the shape or type of subshell is the azimuthal (orbital angular momentum) quantum number. This quantity, which we denote by l, determines whether the subshell is s, p, d, or f, corresponding to the shapes of the orbitals. It can take values from 0 up to n−1 for a given energy level, with l = 0 → s, l = 1 → p, l = 2 → d, and l = 3 → f. The other quantum numbers have different roles: the principal quantum number n sets the energy level and size of the orbital; the magnetic quantum number m_l specifies the orbital’s orientation in space; the spin quantum number m_s indicates the electron’s spin. Therefore, the option describing the subshell type is the one that matches the azimuthal quantum number’s role in determining orbital shape.

The number that sets the shape or type of subshell is the azimuthal (orbital angular momentum) quantum number. This quantity, which we denote by l, determines whether the subshell is s, p, d, or f, corresponding to the shapes of the orbitals. It can take values from 0 up to n−1 for a given energy level, with l = 0 → s, l = 1 → p, l = 2 → d, and l = 3 → f. The other quantum numbers have different roles: the principal quantum number n sets the energy level and size of the orbital; the magnetic quantum number m_l specifies the orbital’s orientation in space; the spin quantum number m_s indicates the electron’s spin. Therefore, the option describing the subshell type is the one that matches the azimuthal quantum number’s role in determining orbital shape.