In the molecule ethene (C2H4), what orbitals are used to form the sigma bond between the two carbon atoms?

• A. s orbitals from each carbon atom
• B. p orbitals from each carbon atom
• C. sp2 orbitals from each carbon atom
• D. sp3 orbitals from each carbon atom

Answer: (C)

Verified step by step guidance

1. Understand that in ethene (C2H4), each carbon atom forms three sigma bonds: two with hydrogen atoms and one with the other carbon atom.
2. Recall that the carbon atoms in ethene are involved in double bonding, which consists of one sigma bond and one pi bond between the carbons.
3. Recognize that to form these bonds, carbon atoms undergo hybridization. In ethene, each carbon atom is sp2 hybridized, meaning one s orbital mixes with two p orbitals to form three sp2 hybrid orbitals.
4. Identify that the sigma bond between the two carbon atoms is formed by the overlap of one sp2 hybrid orbital from each carbon atom.
5. Note that the remaining unhybridized p orbital on each carbon atom overlaps side-by-side to form the pi bond, which is not involved in the sigma bond formation.