Question

The orientation of an atomic orbital is governed by

• A. azimuthal quantum number
• B. spin quantum number
• C. magnetic quantum number
• D. principal quantum number

Answer 1

The Correct Option is C

The given question pertains to the orientation of an atomic orbital, which is a concept in quantum mechanics. Let's analyze the role of each type of quantum number to understand why the magnetic quantum number governs the orientation of an atomic orbital.

1. Principal Quantum Number (n): This number determines the size and energy level of an atomic orbital. It does not govern the orientation. It is represented by positive integers such as 1, 2, 3, etc.
2. Azimuthal Quantum Number (l): Also known as the angular momentum quantum number, it describes the shape of the orbital. For example, s, p, d, and f orbitals have different shapes. However, it doesn't dictate the orientation.
3. Magnetic Quantum Number (m_l): This number governs the orientation of an orbital in space relative to an external magnetic field. It can have values ranging from -l to +l, including zero. For instance, if l = 1 (a p orbital), the magnetic quantum number can be -1, 0, or +1, corresponding to the p_x, p_y, and p_z orbitals.
4. Spin Quantum Number (m_s): It describes the intrinsic spin of the electron within an orbital, with possible values of +1/2 or -1/2. This does not impact orbital orientation.

Among the four quantum numbers, it is the magnetic quantum number (m_l) that primarily determines the orientation of an atomic orbital.

Therefore, the correct answer is: magnetic quantum number.