In chemistry and physics, an orbital is a mathematical expression, called a wave function, that describes properties characteristic of no more than two electrons in the vicinity of an atomic nucleus or of a system of nuclei as in a molecule. An orbital is a three-dimensional description of the most likely location of an electron around an atom. The term atomic orbital may also refer to the physical region or space where the electron can be calculated to be present, as predicted by the particular mathematical form of the orbital.
Each orbital in an atom is characterized by a set of values of the three quantum numbers n, ℓ, and ml, which respectively correspond to the electrons energy, its angular momentum, and an angular momentum vector component (magnetic quantum number) . Atomic orbitals are commonly designated by a combination of numerals and letters that represent specific properties of the electrons associated with the orbitals—for example, 1s, 2p, 3d, 4f. The numerals, called principal quantum numbers, indicate energy levels as well as relative distance from the nucleus.
In summary, an orbital is a mathematical function that describes the wave-like behavior of an electron in an atom or molecule, and it can be used to calculate the probability of finding an electron in any specific region around the atom's nucleus.
