Hybridization of Ethene

Ethene, also known as ethylene, has a molecular formula of C₂H₄. It involves sp²  Hybridization to determine the hybridization of carbon atoms in ethene; we can use the valence bond theory. Let’s explore the Hybridization of Ethene in detail.

1.0Introduction to Hybridization of Ethene

The hybridization of Ethene involves sp² hybridization of carbon atoms, resulting in the formation of sigma bonds with hydrogen and between carbon atoms. Additionally, the unhybridized p orbitals contribute to the formation of a pi bond within the carbon-carbon double bond. This hybridization pattern provides Ethene with its planar structure and double bond characteristics.

The sigma bond in Ethene is a result of the overlap of sp² hybrid orbitals, while the pi bond is formed through the side-to-side overlap of unhybridized p orbitals on the carbon atoms. Let’s discuss the hybridization of Ethene in detail.

2.0Formation of sp² Hybridization in Ethene

As we’ve discussed above, the hybridization of Ethene involves the combination of atomic orbitals on the carbon atoms to form molecular orbitals that facilitate the bonding in the molecule. In Ethene, C₂H₄, there is a carbon-carbon double bond, which consists of one sigma (σ) bond and one pi (π) bond.

Valence Electron Configuration of Carbon:

• • The valence electron configuration of carbon is 2s² 2p², signifying that carbon has a total of four valence electrons distributed across its outermost energy level (2s and 2p orbitals).
  • For hybridization, we consider the valence electrons, which are the electrons in the outermost shell. Carbon has four valence electrons (2s² 2p²).

Hybridization Process:

• • In Ethene, each carbon forms three sigma bonds (σ). For this, carbon undergoes sp² hybridization.
  • The carbon's 2s orbital and two of its 2p orbitals (p_x and p_y) combine to form three sp² hybrid orbitals.
  • The sp² hybrid orbitals are arranged in a trigonal planar geometry, with bond angles of approximately 120 degrees.

Formation of Sigma Bonds:

• • The sigma (σ) bond is formed by the head-on overlap of two sp² hybrid orbitals—one from each carbon atom. This sigma bond is the result of the direct overlap of the orbitals along the internuclear axis.

Formation of Pi Bond:

• • The unhybridized 2p orbitals on each carbon atom overlap laterally to form a pi bond (π) above and below the plane of the molecule.
  • The pi bond is responsible for the double bond character in the carbon-carbon bond.

3.0Bonding and Geometry of Ethene - 

• Molecular Geometry:
• • Since each carbon atom forms three sigma bonds (σ), The sp² hybrid orbitals arrange themselves in a trigonal planar geometry around each carbon atom.
  • The carbon-carbon double bond is formed by the overlap of one sigma bond and one pi bond.
• Bond Angles:
• • The bond angles between the hydrogen atoms and the carbon atoms in the CH₃ groups are approximately 120 degrees.
  • The bond angle in the carbon-carbon double bond region is also approximately 120 degrees.                               

H-C-H bond angle = 117.6°

H-C-C bond angle = 121°

Bond length (C=C) = 134 pm

Bond length (C-H) = 108 pm

To summarize:

• Each carbon atom in ethene undergoes sp² hybridization.
• The resulting sp² hybrid orbitals form sigma bonds with other atoms, and the unhybridized p orbitals overlap to create the pi bond in the carbon-carbon double bond.
• The trigonal planar geometry arises from the arrangement of the three sp² hybrid orbitals around each carbon atom. The bond angles in ethene are consistent with the idealized angles of a trigonal planar structure.

4.0General Properties of Ethene

Ethene is a hydrocarbon with the molecular formula C₂H₄. It is a colorless and odorless gas, and it is a crucial precursor in the production of various plastics and chemicals in the petrochemical industry. Let’s see its properties in detail.