The subatomic scale is the domain of physical size that encompasses objects smaller than an atom. It is the scale at which the atomic constituents, such as the nucleus containing protons and neutrons, and the electrons in their orbitals, become apparent.
The subatomic scale includes the many thousands of times smaller subnuclear scale, which is the scale of physical size at which constituents of the protons and neutrons—particularly quarks—become apparent.
Broadly this may be conveniently divided into:
- Fundamental elementary particles as small as 1×10−19 m, quanta that have not yet been further divided.
- Nuclear or femtometer 1×10−15 m scale related to subatomic particles