Bohr radius

Unit of length about the size of a hydrogen atom

The Bohr radius (⁠ a 0 {\displaystyle a_{0}} ⁠) is a physical constant, approximately equal to the most probable distance between the nucleus and the electron in a hydrogen atom in its ground state. It is named after Niels Bohr, due to its role in the Bohr model of an atom. Its value is 5.29177210544(82)×10−11 m.

From Wikipedia, under CC BY-SA. More on occurri.