The electron in the hydrogen atom can move around the nucleus in a circular path of fixed radius and energy. These paths are called orbits, stationary states or allowed energy states. These orbits ...

An atom of hydrogen is made up of an electron orbiting ... in Switzerland measured the radius of a proton in muonic hydrogen and found it was smaller than previously thought.

The typical size of atoms and small molecules is around 1 × 10-10 m (0.1 nm). For example: diameter of a hydrogen atom, H 1.0 × 10-10 m width of a hydrogen molecule, H 2 2.9 × 10-10 m ...