Fermium Element Facts

General
States
Energies
Oxidation & Electrons
Appearance & Characteristics
Reactions & Compounds
Radius
Conductivity
Abundance & Isotopes

100 Fm 257 Fermium

Fermium is Radioactive.

Name: Fermium
Type: Actinide
Density @ 293 K: 8.84 g/cm³

Discovery of Fermium
Fermium was the eighth synthetic transuranium element of the actinide series to be discovered.

Fermium-255 (half-life 20.07 hours) was identified in 1952 by teams of scientists from the Lawrence Berkeley National Laboratory, the Argonne National Laboratory and the Los Alamos Scientific Laboratory. The project was led by Albert Ghiorso.

It was discovered unexpectedly along with einsteinium in debris from the first large hydrogen bomb test, which took place in the Pacific in November 1952. The debris was collected on filter papers attached to drone airplanes that flew through the explosion area. Later, to obtain more material, many hundreds of pounds of coral from the blast area were examined. Fermium was identified by chemical analysis with only about 200 atoms. ⁽¹⁾

The new element was produced by nuclear fission of 17 neutrons with uranium-238 (which then underwent eight beta decays). ⁽²⁾

The results were not published and kept secret until 1955. In 1954 researchers from the Nobel Institute of Physics in Stockholm produced fermium-250 by bombarding uranium-238 with oxygen-16 ions.

The element was named after the nuclear physicist Enrico Fermi.

Symbol: Fm
Atomic weight: 257
Atomic volume: - cm³/mol

State (s, l, g): solid
Melting point: 1800 K   (1527 ^oC)

Boiling point: K   ( ^oC)

Specific heat capacity: J g^-1 K^-1
Heat of fusion: kJ mol^-1
1^st ionization energy: 627 kJ mol^-1
3^rd ionization energy: kJ mol^-1

Heat of atomization: kJ mol^-1
Heat of vaporization: kJ mol^-1
2^nd ionization energy: kJ mol^-1
Electron affinity: kJ mol^-1

Shells: 2,8,18,32,30,8,2
Minimum oxidation number: 0
Min. common oxidation no.: 0
Electronegativity (Pauling Scale): 1.3

Electron configuration: [Rn] 5f¹² 7s²
Maximum oxidation number: 3
Max. common oxidation no.: 3
Polarizability volume: 23.8 ų

Structure: close packed cubic
Hardness: mohs

Color:


Harmful effects:
Fermium is harmful due to its radioactivity.

Characteristics:
Fermium is a synthetic, highly radioactive metal and has only been produced in miniscule amounts.

Under normal conditions, it behaves in aqueous solution as expected for a trivalent actinide ion.⁽³⁾

Fermium metal has not been prepared. ^(3a)

Uses:
Fermium is of scientific research interest only.

Reaction with air:
Reaction with 15 M HNO₃:
Oxide(s):
Hydride(s):

Reaction with 6 M HCl:
Reaction with 6 M NaOH:
Chloride(s):

Atomic radius: pm
Ionic radius (2+ ion): pm
Ionic radius (2- ion): pm

Ionic radius (1+ ion): pm
Ionic radius (3+ ion): 91.1 pm
Ionic radius (1- ion): pm

Thermal conductivity: W m^-1 K^-1

Electrical conductivity: x 10⁶ S cm^-1