Which quantum number is primarily used to specify the subshells (such as s, p, d, and f) in an atom?

• A. Spin quantum number, m_s
• B. Angular momentum quantum number, l
• C. Principal quantum number, n
• D. Magnetic quantum number, m_l

Answer: (B)

Verified step by step guidance

1. Understand that quantum numbers describe the properties of electrons in atoms, including their energy levels and shapes of orbitals.
2. Recall that the principal quantum number \(n\) specifies the main energy level or shell of an electron.
3. Know that the spin quantum number \(m_s\) describes the intrinsic spin of the electron, which can be either +1/2 or -1/2.
4. Recognize that the angular momentum quantum number \(l\) determines the shape of the orbital and thus specifies the subshell (such as s, p, d, f).
5. Note that the magnetic quantum number \(m_l\) specifies the orientation of the orbital within a subshell.