Bohr radius [b, a.u.] Unit Converter

Definition of Bohr radius [b, a.u.] unit

The Bohr radius, denoted a0, is the characteristic distance between an electron and the nucleus in the ground-state hydrogen atom according to the Bohr model. It equals approximately 5.29177 × 10−11 metres. It is also a fundamental atomic length.

History of Bohr radius [b, a.u.] unit

The Bohr radius was introduced in 1913 by Danish physicist Niels Bohr in his model of the hydrogen atom. Bohr proposed that electrons occupy quantized circular orbits, with the smallest orbit having this characteristic radius. The value follows from fundamental constants: the reduced Planck constant, electron mass, elementary charge, and vacuum permittivity. Although modern quantum mechanics replaces definite orbits with probability distributions, the Bohr radius remains the natural length scale for hydrogenic atoms. It was later named and conventionally denoted a₀, honoring Bohr’s foundational contribution to atomic theory.

Applications of Bohr radius [b, a.u.] unit

Today, the Bohr radius is used primarily as a reference unit in atomic, molecular, and condensed-matter physics. It expresses electron–nucleus distances, orbital sizes, and lengths in hydrogen-like systems. Researchers use it in quantum-mechanical equations, computational chemistry, atomic units, and comparisons of molecular bond lengths, nanostructures, and characteristic scales in electronic materials.

Complete list of Bohr radius [b, a.u.] unit conversion