http://www.reflectometry.org/danse/elements.html https://pypi.python.org/pypi/periodictable This seems to have: - natural crystal structures - density - constants - stable ions - covalent radius - Cromer-Mann (which interestingly in copyright Columbia via @pavoljuhas and @sbillinge) - magnetic form-factor - mass / abundance for isotopes - neutron scattering factors - xray-scattering factors from Henke et al
http://www.reflectometry.org/danse/elements.html
https://pypi.python.org/pypi/periodictable
This seems to have: