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    Individual p subshells are notated npx, npy and npz.

    Individual d subshells are notated ndxy, ndxz, ndyz, ndz^2 and nd(x^2)-y^2.

    When I first learnt about p subshells, I got the impression that x, y and z were arbitrary choices used to differentiate between the three p subshells. However, considering the xz, xy, z^2 etc notation used for d subshells, it seems these letters have more significance (I would have expected it to be something like ndv, ndw, ndx, ndy, ndz).

    What do these letters represent, and also which order do these d subshells fill in (I am assuming p subshells fill in the order npx, npy, npz)?
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    x, y and z are the three coordinate axes in three dimensions

    d orbitals (like p orbitals) are degenerate in elements (they don't have a filling order)
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    (Original post by j.alexanderh)
    Individual p subshells are notated npx, npy and npz.

    Individual d subshells are notated ndxy, ndxz, ndyz, ndz^2 and nd(x^2)-y^2.

    When I first learnt about p subshells, I got the impression that x, y and z were arbitrary choices used to differentiate between the three p subshells. However, considering the xz, xy, z^2 etc notation used for d subshells, it seems these letters have more significance (I would have expected it to be something like ndv, ndw, ndx, ndy, ndz).

    What do these letters represent, and also which order do these d subshells fill in (I am assuming p subshells fill in the order npx, npy, npz)?
    Here's a picture.

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    (Original post by james.h)
    Here's a picture.

    Cheers, fantastic picture, understand perfectly now.

    Edit: Or not. Why is it x^2 take away y^2?
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    The letters denote which plane (co-ordinate axis) the orbital is pointing in.
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    (Original post by j.alexanderh)
    Cheers, fantastic picture, understand perfectly now.

    Edit: Or not. Why is it x^2 take away y^2?
    I really hope I've got this right.

    The shape of the surface given by x^2-y^2:



    The orbitals represent probability densities - so you are most likely to find an electron in the regions enclosed by an orbital.

    If you compare the hyperboloid figure here with the shape of the corresponding orbital in my first post, you can see that the zeroes correspond to the points where the orbital 'vanishes', as it were. The places where the surface is zero, and a small neighbourhood around those points, will have so low a chance to contain an electron that they are excluded from the orbital.

    A similar comparison can be made by considering the surfaces xy, yz, xz, which are various orientations of this shape:



    ...though I've got to admit, I've always been a bit puzzled by the z^2 one. If I had to guess, I'd say its something to do with complex numbers getting involved somewhere, but I really don't know. :dontknow:

    *waits for chemistry student to arrive and explain everything* :o:
 
 
 
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