3p orbitals

The shape of the three 3p orbitals. From left to right: 3p_y, 3p_z, and 3p_x. For each, the yellow zones are where the wave functions have positive values and the white zones denote negative values.

The three 3p orbitals. Use the previous and next icons to see other views

The three 3p orbitals including orbital nodes. Use the previous and next icons to see other views

Nodes of the three 3p orbitals. Use the previous and next icons to see other views

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For any atom, there are three 3p orbitals. These orbitals have the same shape but are aligned differently in space. The three 3p orbitals normally used are labelled 3p_x, 3p_y, and 3p_z since the functions are "aligned" along the x, y, and z axes respectively.

Each 3p orbital has four lobes. There is a planar node normal to the axis of the orbital (so the 3p_x orbital has a yz nodal plane, for instance). Apart from the planar node there is also a spherical node that partitions off the small inner lobes. The higher p-orbitals (4p, 5p, 6p, and 7p) are more complex still since they have more 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 4p_x orbital. When x = 0, then there is a node, and this by definition is the yz plane.

The origin of the spherical node becomes clear when inspecting the wave equations which, for instance, include (4 - ρ) terms. When (4 - ρ) = 0, then there is a node. Since for any 3p orbital ρ = 2Zr/3 (Z = effective nuclear charge, r = radius in atomic units), then the nodes are at the radius for which (4 - 2Zr/3) = 0, that is, r = 6/Z atomic units.