Answer is:
18 electrons.
The principal quantum number (n) is one
of four quantum numbers which are assigned to each electron in an atom to
describe that electron's state.
The azimuthal quantum number (l) is a quantum number for
an atomic orbital that determines its orbital angular
momentum and describes the shape of the orbital, l = 0....n-1.
For n = 3, l = 0, 1, 2.
l = 0, s orbital with 2 electron.
l = 1, p orbitals with 6 electrons.
l = 2, d orbitals with 10 electrons.
2 + 6 + 10 = 18 electrons.
