Let an electron is orbiting in a orbit with the principal quantum number n =1. According to wave mechanics its angular momentum is √ l(l+1) h/2∏ and angle : cosθ = ml/ √ l(l+1) How one can explain the electron angular momentum and its possible orientations for l =0? Off course for n =2, l = 0& 1. For l = 1 we can get the angles θ, however, it is not possible for l=0. How one can explain the zero angular momentum for the electron in the innermost orbit ie., n = 1? How to explain the possible orientation of the orbit for l =0?