| Here are rotatable
representations of the shapes of s, p and d orbitals. These shapes are
derived from the angular portion of the orbital wavefunctions, and are
independent of the principle quantum number, n. Only the size of a particular
orbital would change as n changes. In other words, in terms of shape all
p orbitals look the same. The two colors represent the signs of the various
lobes of the orbital wavefunctions - red is positive and blue negative.
These colors are also often referred to as the phase of the wavefunction.
The signs or phases are important in chemical bonding. Orbital regions
of like-sign on two or more atoms interact (or overlap) with constructive
intereference, and produce bonding interactions, whereas regions of opposite
sign interact with destructive interference and produce antibonding interactions.
The signs of the various lobes can be derived easily from the label for
the orbital. For example, if you are talking about the pz orbital, the
lobe in the +z direction is positive (red) and in the -z direction is
negative (blue). For the dxz obital, the product xz is positive in the
(+x, +z) and (-x, -z) quadrants, and negative in the (+x, -z) and (-x,
+z) quadrants. Lastly, the orbital we refer to as dz2 is more correctly
d2z2-x2-y2, and this formulation predicts the signs correctly. |
