Which quantum number primarily determines the energy level of an electron in an atom?

• A. Principal quantum number (n)
• B. Spin quantum number (s)
• C. Magnetic quantum number (m)
• D. Azimuthal quantum number (l)

Answer: (A)

Verified step by step guidance

1. Understand that quantum numbers are used to describe the properties of electrons in atoms. Each quantum number provides specific information about the electron's position and energy.
2. Identify the four types of quantum numbers: Principal quantum number (n), Azimuthal quantum number (l), Magnetic quantum number (m), and Spin quantum number (s).
3. Recognize that the Principal quantum number (n) is the one that primarily determines the energy level of an electron in an atom. It indicates the main energy level or shell in which the electron resides.
4. The Principal quantum number (n) is a positive integer (n = 1, 2, 3, ...) and as n increases, the energy level and the average distance of the electron from the nucleus also increase.
5. The other quantum numbers (l, m, s) provide additional information about the electron's angular momentum, orientation, and spin, but do not primarily determine the energy level.