Molecular orbital configurations give rise to electronic terms comprising corresponding electronic states. Electronic terms possess symmetry classifications, which are denoted by a term symbol, based on the symmetry properties of the electronic wave functions associated with the states. Using the methylene radical, and both planar and twisted ethylene molecules as examples, the symmetry classifications of the wave functions connected to orbital configurations are determined. The wave functions associated with the open-shell ···(2e)[superscript 2] ground configuration of twisted, D[subscript 2d] ethylene present an informative example of how to use group theory to determine the configuration state functions associated with the six states arising from this configuration.