Periodic Table


Atomic number: 100
Atomic weight: 257
Symbol: Fm
Group number: (actinide)
Electronic configuration: [Rn].5f12.7s2


Fermium's chemical properties are largely unknown. Fermium is a radioactive rare earth metal. The longest living isotope is is 257Fm with a half-life of 80 days. It is of no commercial importance.

General information

Discoveror: Workers at Argonne, Los Alamos, USA, and the University of California at Berkeley, USA.
Date discovered: 1952
Discovered at: USA
Meaning of name: Named after "Enrico Fermi"

Physical data

Standard state: unknown but presumably a solid at 298 K
Colour: thalpy


This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Fm.html