What is a sigma bond?

What is a sigma bond?

• A. Sigma bond
• B. Pi bond
• C. Double bond
• D. Hydrogen bond

Answer: (A)

A sigma bond is formed by end-to-end overlap of atomic orbitals along the line between the two nuclei, placing electron density directly between the atoms. This head-on overlap creates a strong covalent connection that defines a single bond and lies along the internuclear axis. Because the electron density is concentrated along that axis, sigma bonds are the first type of bond built when atoms share electrons, and they allow rotation around the bond axis in many cases (rotation is possible unless restricted by other factors in a molecule). In a molecule with more than one bond between two atoms, the additional bonds come from pi interactions, which arise from sideways overlap of p orbitals above and below the bond axis. A double bond is made up of one sigma bond plus one pi bond, so the term describes the combination, not the entire bond itself. Hydrogen bonds, by contrast, are non-covalent attractions involving a hydrogen attached to a highly electronegative atom and are not covalent sigma bonds.

A sigma bond is formed by end-to-end overlap of atomic orbitals along the line between the two nuclei, placing electron density directly between the atoms. This head-on overlap creates a strong covalent connection that defines a single bond and lies along the internuclear axis. Because the electron density is concentrated along that axis, sigma bonds are the first type of bond built when atoms share electrons, and they allow rotation around the bond axis in many cases (rotation is possible unless restricted by other factors in a molecule).

In a molecule with more than one bond between two atoms, the additional bonds come from pi interactions, which arise from sideways overlap of p orbitals above and below the bond axis. A double bond is made up of one sigma bond plus one pi bond, so the term describes the combination, not the entire bond itself. Hydrogen bonds, by contrast, are non-covalent attractions involving a hydrogen attached to a highly electronegative atom and are not covalent sigma bonds.