The linear combination of a single 4s-orbital with one 4p-orbital (4p_x here) results in two 4sp-orbitals of identical shape, but different orientation in space. The images below provide an illustration of the probability contours (90-25% probability level of the electron density, i.e. ψ²) and the nodal plane of a 4sp-orbital (actually not a "planar" plane; ψ = 0), where different colors indicate regions of opposite sign in ψ. The nucleus is located at the origin of the coordinate system as indicated by the orange axes, and thus is embedded not between the lobes on the nodal plane, but within the minor (blue) lobe of the hybrid orbital.

In the bottom row, both 4sp-orbitals and their relative arrangement (linear, with opposite directionality) are displayed, but note that the orbitals have been moved away from the center towards the outside to facilitate visualization (the orange spheres represent the original location of the nucleus). Click on the images to enlarge view or see the VRML 3D-model.

90% Probability Contour	90-25% Probability Contours	Nodal Plane
Both 4sp-Hybrid Orbitals	Both 4sp-Hybrid Orbitals	Both 4sp-Hybrid Orbitals

LCAOs:

ψ1  =  1/√2 φ4s  +  1/√2 φ4px ψ2  =  1/√2 φ4s  -  1/√2 φ4px

All graphics shown on this page were created using the MolArch⁺ program and POVRAY Persistence of Vision Raytracer. Hybrid Orbitals were generated from the pure hydrogenic wave functions of 4s- and 4p-orbitals; Cartesian wave functions were taken from The Orbitron Gallery of Atomic Orbitals and Molecular Orbitals.