Which of the following statements correctly describes the principal quantum number (n) for atomic orbitals?

• A. It determines the overall size and energy of an orbital.
• B. It specifies the orientation of an orbital in space.
• C. It describes the spin direction of an electron in an orbital.
• D. It indicates the shape of an orbital.

Answer: (A)

Verified step by step guidance

1. Understand that the principal quantum number, denoted as \(n\), is one of the four quantum numbers used to describe atomic orbitals and electrons within an atom.
2. Recall that \(n\) primarily determines the energy level and the relative size of the orbital. As \(n\) increases, the orbital becomes larger and the electron is generally found farther from the nucleus.
3. Recognize that \(n\) does not specify the orientation of the orbital in space; this role belongs to the magnetic quantum number \(m_l\).
4. Know that the spin direction of an electron is described by the spin quantum number \(m_s\), not by \(n\).
5. Remember that the shape of an orbital is determined by the azimuthal (angular momentum) quantum number \(l\), not by \(n\).