Question

valence electrons are usually defined in terms of highest ______ quantum number.
a magnetic
b spin
c azimuthal
d principal

Explanation:

Valence electrons are the outermost electrons of an atom. The principal quantum number (\(n\)) represents the energy level or shell of an electron. Valence electrons are in the highest - energy shell (highest \(n\) value). The magnetic quantum number (\(m_l\)) describes the orientation of an orbital within a sub - shell. The spin quantum number (\(m_s\)) describes the spin of an electron (\(+\frac{1}{2}\) or \(-\frac{1}{2}\)). The azimuthal quantum number (\(l\)) describes the shape of an orbital (\(l = 0\) for \(s\) - orbitals, \(l=1\) for \(p\) - orbitals etc.). Since valence electrons are in the outermost shell (highest \(n\)), they are defined in terms of the highest principal quantum number.

Answer:

d. Principal