Element-symbol utilities

The wnutils.base.Base class converts between atomic numbers and element symbols. Since the other wnutils classes inherit from Base, the same methods are available from XML and HDF5 objects.

Use get_element_symbol() to retrieve a symbol from an atomic number:

>>> import wnutils.base as wnb
>>> base = wnb.Base()
>>> base.get_element_symbol(29)
'Cu'
>>> base.get_element_symbol([18, 29, 120])
['Ar', 'Cu', 'Ubn']
>>> base.get_element_symbol(29, lowercase=True)
'cu'

Use get_atomic_number() for the reverse conversion. Input symbols are case-insensitive:

>>> base.get_atomic_number('Cu')
29
>>> base.get_atomic_number('cu')
29
>>> base.get_atomic_number(['Ar', 'cu', 'ubn'])
[18, 29, 120]

Lists and tuples retain their container types. NumPy arrays retain their shape and are returned with object dtype so that temporary atomic numbers are not restricted to a fixed-width integer type.

Temporary systematic symbols

For atomic numbers above 118, the methods generate and recognize systematic temporary symbols. The conversion has no artificial upper limit:

>>> base.get_element_symbol(1220)
'Ubbn'
>>> base.get_atomic_number('uohbb')
18622

These conversions apply the systematic symbol rules; they do not indicate that an element exists or has received an official name.

Nitrogen and neutron notation

Element symbols are case-insensitive, so both "N" and "n" mean nitrogen in get_atomic_number() and return Z = 7. The special interpretation of "n" as a neutron remains available when parsing a nuclide name:

>>> base.get_atomic_number('n')
7
>>> base.get_z_a_state_from_nuclide_name('n')
(0, 1, '')

Invalid symbols, non-integral atomic numbers, and atomic numbers below one raise an exception rather than returning a sentinel value.