plasmapy.atomic.known_isotopes(argument: Union[str, numbers.Integral] = 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_isotopesreturns isotopes with non-zero

isotopic abundances.

stable_isotopesreturns 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