Sigma Orbital
Definition and meaning of Sigma Orbital in chemistry.
A sigma orbital is a fundamental molecular orbital formed by the direct, head-on overlap of atomic orbitals, resulting in localized electron density concentrated directly along the internuclear axis between two bonded atoms.
In more detail
Sigma orbitals are primarily responsible for the formation of standard single covalent bonds and generally represent the strongest type of covalent bond due to the absolute maximum spatial overlap of the constituent atomic orbitals. They can be readily formed from the symmetrical overlap of s-s, s-p, or p-p atomic orbitals, as well as various hybridized orbitals. Because the resulting electron density is perfectly cylindrically symmetric around the central bond axis, bonded atoms can essentially rotate freely around a single sigma bond without breaking it.
Key facts
| Field | Organic Chemistry |
|---|---|
| Symmetry | Cylindrical |
| Bond Type | Single bond |
The stable single bond between the two adjacent carbon atoms in an ethane (C2H6) molecule is formed by the strong head-on overlap of two sp3 hybridized orbitals to create a defining sigma orbital.
Frequently asked questions
How exactly does a sigma bond structurally differ from a pi bond?
A sigma bond concentrates its electron density directly along the internuclear axis, while a pi bond features electron density located above and below this axis due to parallel, side-by-side atomic orbital overlap.