MeSH definition : A radioactive alkali metal with the atomic symbol Fr, and atomic number 87. The mass
numbers of known isotopes are 204-213, 217-224. Its valence is 1.;
MeSH CAS label : francium;
MeSH Related Number : 7440-73-5 (Francium);
Registry Number MeSH : 7440-73-5;
MeSH annotation : naturally radioactive; IM;
Wikipedia link : https://en.wikipedia.org/wiki/Francium;