S Orbital
Definition and meaning of S Orbital in chemistry.
An s orbital is a spherically symmetric atomic orbital characterized by an angular momentum quantum number l = 0, in which electrons reside around an atom's nucleus.
In more detail
S orbitals are the simplest type of atomic orbital and form the basis of electron configuration in all atoms. Each s orbital is identified by its principal quantum number n, producing the 1s, 2s, 3s, and higher orbitals with progressively higher energy levels. The 1s orbital is the lowest-energy orbital and fills first during electron configuration; for example, a hydrogen atom's single electron occupies the 1s orbital in its ground state. The spherical symmetry of s orbitals arises directly from their l = 0 quantum number, meaning electrons in s orbitals have no net orbital angular momentum.
Key facts
| Field | Physical Chemistry |
|---|---|
| Angular momentum quantum number | l = 0 |
| Shape | Spherically symmetric around nucleus |
| Examples | 1s, 2s, 3s, 4s, 5s orbitals |
A sodium atom has the electron configuration 1s2 2s2 2p6 3s1, where the unpaired electron in the 3s orbital accounts for sodium's characteristic reactivity and its position as a Group 1 metal.
Frequently asked questions
How many electrons can occupy an s orbital?
A maximum of 2 electrons can occupy any s orbital, following the Pauli exclusion principle and the rule that each orbital can hold a maximum of 2 paired electrons.
Why is it called an 's' orbital?
The designation 's' comes from historical spectroscopy notation, where 's' stood for 'sharp,' one of four categories used to classify spectral lines in the 19th century (sharp, principal, diffuse, fundamental).