Fermium

History

(Enrico Fermi) Fermium, the eighth discovered transuranium element of the actinide series, was identified by Ghiorso and co-workers in 1952 in the debris from a thermonuclear explosion in the pacific during work involving the University of California Radiation Laboratory, Argonne National Laboratory, and Los Alamos National Laboratory.

The isotope produced was the 20-hour 255Fm. During 1953 and early 1954, while discovery of elements 99 and 100 was withheld from publication for security reasons, a group from the Nobel Institute of Physics in Stockholm bombarded 238U with 16O ions, and isolated a 30-min alpha-emitter, which they ascribed to 250Fm, without claiming discovery of the element. This isotope has since been identified positively, and the 30-min half-life confirmed.[1]

Properties

General
Name : fermium
Symbol : Fm
Atomic Number : 100
Chemical Series : Actinide
Block, Period : -, 7
Appearance : unknown
Atomic Properties
Atomic Weight (amu) : 257
Covalent Radius (pm) : n/a
Physical Properties
Matter : presumably a solid (radioactive) (synthetic)
Density (kg/) : n/a
Hardness : n/a
Melting Point (K) : n/a
Boiling Point (K) : n/a
Evaporation Heat (kJ/mol) : n/a
Fusion Heat (kJ/mol) : n/a
Specific Heat (J/(kg*K) ) : n/a
Miscellaneous
Electrical Conductivity (/m ohm) : n/a
Thermal Conductivity (W/(m*K) ) : n/a

The chemical properties of fermium have been studied solely with tracer amounts. In normal aqueous media, only the (III) oxidation state appears to exist.[1]

Isotopes

254Fm and heavier isotopes can be produced by intense neutron irradiation of lower elements, such as plutonium, using a process of successive neutron capture interspersed with beta decays until these mass numbers and atomic numbers are reached.

Sixteen isotopes of fermium are known to exist. 257Fm, with a half-life of about 100.5 days, is the longest lived. 250Fm, with a half-life of 30 minutes, has been shown to be a decay product of element 254No. Chemical identification of 250Fm confirmed the production of element 102 (nobelium).[1]

Notes

[1] From Los Alamos National Laboratory's Chemistry Division Website