Sigma Bond

Definition

A sigma bond is a type of covalent chemical bond formed by the head-on overlap of atomic orbitals, resulting in a high electron density concentrated along the internuclear axis between two bonded atoms. This type of bond is the strongest and most common type of covalent bond, and it plays a crucial role in the stability and structure of molecules.

5 Must Know Facts For Your Next Test

1. Sigma bonds are the strongest type of covalent bonds, with a high electron density concentrated along the internuclear axis.
2. Sigma bonds are formed by the head-on overlap of atomic orbitals, typically s-s, s-p, or p-p overlaps.
3. Sigma bonds are the primary contributors to the stability and structure of molecules, providing the framework for more complex bonding arrangements.
4. In the context of valence bond theory, sigma bonds are formed by the overlap of hybridized atomic orbitals.
5. Sigma bonds are essential for the formation of multiple bonds, such as double and triple bonds, where they are complemented by pi bonds.

Review Questions

• Explain the role of sigma bonds in the context of valence bond theory.
  • In the valence bond theory, sigma bonds are formed by the head-on overlap of hybridized atomic orbitals, such as sp, sp2, or sp3 orbitals. These sigma bonds provide the primary framework for the stability and structure of molecules, as they concentrate a high density of electrons along the internuclear axis between the bonded atoms. The formation of sigma bonds is a key step in understanding how atoms combine to form stable chemical compounds according to the valence bond theory.
• Describe how sigma bonds are related to the concept of hybrid atomic orbitals.
  • The formation of sigma bonds is closely linked to the concept of hybrid atomic orbitals in the context of valence bond theory. When atoms form covalent bonds, their atomic orbitals can undergo hybridization, where the original s, p, and d orbitals combine to form new hybrid orbitals. These hybrid orbitals, such as sp, sp2, or sp3, are then used to form sigma bonds through head-on overlap. The specific type of hybridization determines the geometry and stability of the resulting molecule, with the sigma bonds playing a crucial role in defining the overall molecular structure.
• Analyze the importance of sigma bonds in the formation of multiple bonds, such as double and triple bonds.
  • Sigma bonds are essential for the formation of multiple bonds, such as double and triple bonds. In these cases, the sigma bond provides the primary framework, while additional pi bonds are formed by the side-on overlap of p orbitals. The combination of sigma and pi bonds results in the formation of stronger and more stable multiple bonds, which are crucial for the structure and reactivity of many organic and inorganic compounds. The presence of sigma bonds, along with the complementary pi bonds, allows for the creation of a wide variety of molecular geometries and enables the diversity of chemical structures observed in nature.

Related terms

Covalent Bond:

A chemical bond formed by the sharing of one or more pairs of electrons between two atoms.

Atomic Orbital: A mathematical function that describes the wave-like behavior of an electron in an atom.

Overlap: The interaction between atomic orbitals that allows the formation of chemical bonds.