The C=S double bond in carbon disulfide (CS₂) consists of a combination of one σ bond and one π bond. Compared to the bond dissociation energy (bond strength) of the π bond, the bond dissociation energy of the σ bond portion of the C=S bond is:

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11ecba2d_124e_51ba_a3bf_1f5036c73077_MD0008_00 Covalent bonds formed by sharing electrons through an end-to-end overlap of orbitals are called sigma (σ) bonds, whereas covalent bonds made by the side-to-side overlap of p orbitals are called pi (π) bonds. Although some atoms participate only in single covalent bonding (by a σ bond), other atoms can participate in double or triple bonds by the addition of π bonds. As such, a double bond consists of one σ bond and one π bond, and a triple bond consists of one σ bond and two π bonds. Stronger bonds require more energy to break (dissociate) than weaker bonds. The overall strength of a bond results from the sum of all σ and π bonding contributors. As a result, when comparing bonds involving the same two types of atoms, a triple bond is stronger than a double bond, and a double bond is stronger than a single bond because double and triple bonds are composed of both σ and π bonds. However, if the strengths of the σ bond and π bond contributors are considered separately, π bonds are weaker than σ bonds. The end-to-end orbital overlap in σ bonds is more efficient than the side-to-side orbital overlap in π bonds. This causes σ bonds to exist in a more stable, lower energy state. As a result, breaking a σ bond requires more added energy than breaking a π bond (ie, a σ bond has a greater dissociation energy). (Choices B, C, and D) Due to differences in the efficiency and mode of the orbital overlap, σ and π bond dissociation energies are not equivalent or proportional, and σ bonds require more energy than π bonds to be broken. Educational objective: Sigma bonds are lower in energy, more stable, and have a greater dissociation energy than π bonds. Although individual π bonds are weaker than σ bonds, double and triple bonds are composed of both σ and π bonds and are therefore stronger overall than a single bond.

The C=S Double Bond in Carbon Disulfide (CS2) Consists of a Combination

The C=S Double Bond in Carbon Disulfide (CS₂) Consists of a Combination