plasmapy.atomic.known_isotopes(argument: Union[str, int] = None) → List[str]

Return a list of all known isotopes of an element, or a list of all known isotopes of every element if no input is provided.


argument (int or str, optional) – A string representing an element, isotope, or ion or an integer representing an atomic number


isotopes_list – List of all of the isotopes of an element that have been discovered, sorted from lowest mass number to highest mass number. If no argument is provided, then a list of all known isotopes of every element will be returned that is sorted by atomic number, with entries for each element sorted by mass number.

Return type:

list containing str items or an empty list

  • InvalidElementError – If the argument is a valid particle but not a valid element.
  • InvalidParticleError – If the argument does not correspond to a valid particle.
  • TypeError – If the argument is not a str or int.


This list returns both natural and artificially produced isotopes.

See also

common_isotopes : returns isotopes with non-zero
isotopic abundances.
stable_isotopes : returns isotopes that are
stable against radioactive decay.


>>> known_isotopes('H')
['H-1', 'D', 'T', 'H-4', 'H-5', 'H-6', 'H-7']
>>> known_isotopes('helium 1+')
['He-3', 'He-4', 'He-5', 'He-6', 'He-7', 'He-8', 'He-9', 'He-10']
>>> known_isotopes()[0:10]
['H-1', 'D', 'T', 'H-4', 'H-5', 'H-6', 'H-7', 'He-3', 'He-4', 'He-5']
>>> len(known_isotopes())  # the number of known isotopes