In 1874, van’t Hoff and Le Bel published separate papers advancing the hypothesis that the four bonds from a central carbon extend tetrahedrally. This marked the beginning of the field of stereochemistry. Part of their justification was that there was only one known compound with the formula CH₂X₂. Using the compound CH₂F₂ as an example, determine the expected number of isomers if the orientation of the bonds to a carbon atom is tetrahedral and the expected number if the orientation is square-planar.