Atoms

Gives the distance of closest approach of an alpha particle with kinetic energy K in a head-on collision with a nucleus.

Quantizes the orbital angular momentum of an electron in stationary Bohr orbits to integral multiples of h/(2pi).

Gives the radius of the nth orbit for a hydrogen-like atom of atomic number Z.

Gives the orbital speed of an electron in the nth Bohr orbit of a hydrogen-like atom.

Relates the total energy, kinetic energy, and potential energy of an orbiting electron in a Coulomb field.

Gives the quantized total energy of an electron in the nth orbit of a hydrogen-like atom.

States that the frequency of the emitted or absorbed photon is proportional to the energy difference between two stationary states.

Calculates the wavelength of radiation emitted in an electron transition between principal quantum numbers n2 and n1.

Gives the total number of distinct spectral emission lines possible when electrons de-excite between two levels.

Relates the circumference of the nth stable Bohr orbit to an integral number of electron de Broglie wavelengths.

Gives the effective mass replacing electron mass when nuclear motion is considered, as in muonic atoms or positronium.