[Schrödinger]

Which electron has a higher energy:
clockwise spin or anti clockwise spin?

If one of them has lower energy than the other, then should it be given more preference while filling an obital?
i.e, if clockwise has lower energy, then whould we start by filling empy orbitals with those electrons first???

[Hunt]

You have to specify the system in which the electron is located. If the system is a certain isolated atom, and as long as there's no perturbation ( an electric field , magnetic field , etc. ) done on this system, the energy is not a function of the spin quantum number. An electron with ms=1/2 or -1/2 will have the same energy , all other quantum numbers being the same.

[Schrödinger]

u mean to say that it's ok to use any quantum number to fill the orbitals first?

[Hunt]

Yes you can use 'spin up' or 'spin down' when filling electrons , the energy is not affected, but remmeber to include Hund's rule for maximum multiplicity. That is , suppose you're filling 3 e's in a d orbital , then all 3 electrons must be 'spinning' either clockwise or anti-clockwise. I hope this helps , if not , check out any general chemistry textbook on that.

[Schrödinger]

thanx a lot