plasmapy.particles.particle_mass(particle: plasmapy.particles.particle_class.Particle, *, Z: numbers.Integral = None, mass_numb: numbers.Integral = None)astropy.units.quantity.Quantity

Return the mass of a particle.

  • particle (str, int, or Particle) – A string representing an element, isotope, ion, or special particle; an integer representing an atomic number; or an instance of the Particle class.

  • Z (int, optional, keyword-only) – The ionization state of the ion.

  • mass_numb (int, optional, keyword-only) – The mass number of an isotope.


mass – The mass of the particle.

Return type


  • TypeError – The argument is not a string, integer, or Quantity.

  • InvalidParticleError – If the argument does not correspond to a valid particle.

  • MissingParticleDataError – If the standard atomic weight, the isotope mass, or the particle mass is not available.


This function will return the ion mass for ions, the isotope mass for isotopes (when available), the standard atomic weight for elements (when available), or the mass of special particles, as appropriate.

The masses of neutrinos are not available because primarily upper limits are presently known.