What determines the radius of atomic orbitals, such as in B₁₂?

Azimuthal quantum number (ℓ)

Magnetic quantum number (m)

Spin quantum number (s)

Principal quantum number (n²)

Explanation

The radius of an atomic orbital increases with the square of the principal quantum number (n).
So, larger values of n result in electrons being farther from the nucleus:

$Radius \propto n^{2}$