English: Carbenes of different electron configurations and geometrical shapes.

Left: Singulet carbene. The central carbon is sp²-configured. Two sp² orbitals are involved in covalent bonds with the two substituents. Both electrons occupy the third sp² orbital and the remaining p-orbital is not occupied. This is the typical shape of carbenes with substituents that have a free electron pair adjacent to the central carbon, for instance :CCl₂.
Center: Triplet carbene, bent. The central carbon is again sp²-configured, but the two additional electrons occupy both the third sp² orbital and the remaining p-orbital. This is the typical shape of carbenes with substituents lacking free electron pairs. Examples are :CH₂ and :CHPh.

Right: Triplet carbene, straight. The central carbon is sp-configured, resulting in a straight geometry (like in alkynes). The two free electrons occupy the two degenerate p-orbitals. This form is less common than the bent variants.