what is the radius of the hydrogen atom
Bohr radius The Bohr radius (a0 or rBohr) 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 6989529177210670000♠5.2917721067(12)×10−11 m.[1][note 1]