What is the hybridization of a carbon atom in ethene (C2H4)?

In ethene (C2H4), each carbon atom is bonded to two hydrogen atoms and forms a double bond with the other carbon atom. To determine the hybridization of the carbon atom, one must consider the arrangement of electron pairs and the geometry around the carbon.

Each carbon atom in ethene is involved in three regions of electron density: two single bonds with hydrogen atoms and one double bond with the other carbon atom. This leads to a total of three regions of electron density around each carbon atom, which corresponds to a trigonal planar geometry.

In a trigonal planar arrangement, the carbon atom's 2s and two of its 2p orbitals hybridize to form three equivalent sp² hybrid orbitals. The third p orbital remains unhybridized and is used to form the pi bond typically found in double bonds.

Thus, the correct hybridization for each carbon atom in ethene is sp², reflecting the need for three orbitals to accommodate the bonding scheme in this molecule. This hybridization results in bond angles of approximately 120 degrees, consistent with the observed geometry of ethene.