In the p sub shell there are 3 orbitals, m=-1, m=0, m=1 which are listed by axis x,y, and z. Some show as -1=x,0=y,1=z Another shows -1=x,0=z,1=y Some pictures and text also show the filling order as ‘xyz’ and others state that the z axis is filled first m=0 and then the x axis as m=-1 making the filling order z,x,y

What is the correct filling order? If I know this then I can figure out the d and f sub shells. d~m=-2,-1,0,1,2 F-m=-3,-2,-1,0,1,2,3 Thanks, HJS

  • $\begingroup$ Your question makes no sense - orbitals don't have "direction" or "number" written on them. $\endgroup$ – Mithoron Feb 10 '18 at 22:42
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    $\begingroup$ @Mithoron Well, they sure don't have anything written on them per se, but they do have different orientations in space, don't they? For example, the three p orbitals have different orientation along the $x,y,z$ axes. $\endgroup$ – Gaurang Tandon Feb 11 '18 at 11:38
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    $\begingroup$ @GaurangTandon technically no. We can define a set of axes around a molecule and then write the wavefunction of the p-orbitals in such a way where it lines up with those axes, but this is more about how we choose to define our basis of states than something intrinsic about the orbitals. en.wikipedia.org/wiki/Atomic_orbital#Real_orbitals $\endgroup$ – Tyberius Feb 12 '18 at 4:35
  • $\begingroup$ @Tyberius You mean to say that if we remove the coordinate axes then all the orbitals are symmetric with each other. Alright, I get it! BUT how does this explain $d_{z^2}$ as compared to the other $d$ oribtals? Surely the former is not at all symmetric with the others even if we remove the coordinate axes... $\endgroup$ – Gaurang Tandon Feb 12 '18 at 4:38

There is no order for filling atomic orbitals of the same azimuthal quantum number (l) such as px, py, and pz since they are degenerate ie. have the same energy (however they lose their degeneracy in a magnetic field, see Zeeman effect). Therefore, one electron in a p sub-cell can be in either 3 of them and the order of filling doenst matter. For when more electrons are added in degenerate orbitals look up Hund's rule and the Pauli principle.


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