In quantum mechanics, an orbital is a mathematical function that describes the wave-like characteristics of an electron, electron pair, or, less frequently, nucleons. Alternatively known as an atomic orbital or electron orbital, an orbital is not confined to the circular notion commonly associated with an “orbit.” The probability density regions housing an electron can assume various shapes, including spherical, dumbbell-shaped, or more intricate three-dimensional forms.
The mathematical function serves the purpose of delineating the likelihood of finding an electron within a specific region around, or hypothetically within, an atomic nucleus.
Characteristics
- An orbital may refer to an electron cloud characterized by specific values of the n, ℓ, and mℓ quantum numbers.
- Each electron is uniquely defined by a set of quantum numbers.
- An orbital can accommodate two electrons with paired spins and is associated with a distinct region within an atom.
- The s, p, d, and f orbitals correspond to angular momentum quantum numbers ℓ = 0, 1, 2, and 3, respectively.
- These letters (s, p, d, f) originate from the descriptions of alkali metal spectroscopy lines, signifying sharp, principal, diffuse, or fundamental appearances.
- Following s, p, d, and f, orbital names for ℓ > 3 are alphabetical (g, h, i, k, …).
- The letter ‘j’ is omitted because it doesn’t differ from ‘i’ in all languages.
Properties of Electrons in Orbitals
Electrons display wave-particle duality, which means they exhibit some properties of particles and some characteristics of waves.
| Particle Properties | Wave Properties | |
|---|---|---|
| Electrons | Electrons have particle-like properties, including a -1 electrical charge. | Electrons behave like waves, akin to a photon of light. |
| Electron Count | The number of electrons around an atomic nucleus is an integer value. | It’s not possible to pinpoint the exact location of an electron, but the probability of finding one can be described within a region specified by a wave function. |
| Orbital Movement | Electrons move between orbitals in a manner resembling particles. | Electrons do not orbit the nucleus like planets; instead, their movement is akin to standing waves, with energy levels comparable to harmonics on a vibrating string. |
| Energy Changes | Energy changes in electrons occur when they move between energy levels, influenced by factors like absorbed photons. | The energy levels of electrons are like harmonics on a vibrating string. Lower levels are akin to the fundamental frequency, while higher levels resemble harmonics. |
| Location Concept | Commonly perceived as individual solid particles. | The location of an electron cannot be precisely pinpointed; it is more accurately described by the probability of finding it within a region determined by a wave function. |
| Orbital Structure | Electrons don’t orbit like planets but exist in standing waves. The region they might occupy is comparable to a cloud or atmosphere. | The region containing an electron is cloud-like, especially when an atom has only one electron (spherical probability). |
