The shape of the three 5p orbitals. From left to right: 5py, 5pz, and 5px. For each, the yellow zones are where the wave functions have positive values and the white zones denote negative values.
For any atom, there are three 5p orbitals. These orbitals have the same shape but are aligned differently in space. The three 5p orbitals normally used are labelled 5px, 5py, and 5pz since the functions are "aligned" along the x, y, and z axes respectively.
Each 5p orbital has eight lobes. There is a planar node normal to the axis of the orbital (so the 5px orbital has a yz nodal plane, for instance). Apart from the planar node there are also three spherical nodes that partition off the small inner lobes. The higher p-orbitals (6p, and 7p) are more complex still since they have additional spherical nodes.
The origin of the planar node becomes clear when inspecting the wave equations which, for instance, includes an x term in the case of the 5px orbital. When x = 0, then there is a node, and this by definition is the yz plane.
The origin of the spherical nodes becomes clearer when inspecting the wave equations which which include (120 - 90ρ + 18ρ2 - ρ3) terms. When (120 - 90ρ + 18ρ2 - ρ3) = 0, then there are nodes.
The OrbitronTM, a gallery of orbitals on the WWW: https://winter.group.shef.ac.uk/orbitron/
Copyright 2002-2021 Prof Mark J. Winter [Department of Chemistry, The University of Sheffield]. All rights reserved.