An Overview about the Chemical Element Fermium


Symbol: Fm

Atomic Number: 100

Atomic Mass: 257 amu (atomic mass units)

Melting Point: 1527C (1800 K, 2781F)

Boiling Point: Unknown

Number of Protons: 100

Number of Electrons: 100

Number of Neutrons: 157

Classification: Rare Earth Metal (Man Made)

Crystal Structure: Unknown

Density @ 293 K: Unknown

Color: Unknown

In 1952 the debris from a thermonuclear device detonated in the South Pacific was being examined by a team of American scientists under the leadership of Albert Ghiorso. They were working out of three different laboratories within the USA, the Argonne National Laboratory, the Los Alamos National Laboratory and the University of California at Berkeley. The found a minute quantity of a previously unknown element. This was found to be element 100 and was the eighth of the trans-uranium elements to be discovered.

The new element was called Fermium after the Italian Nobel Prize winning physicist Enrico Fermi (1901-1954) who built the first controlled nuclear pile at the University of Chicago and also worked on the Manhattan project.

At the time the discovery of a new element was not announced to the public owing to the National Security surrounding much of the USA’s work on the hydrogen bomb. This secrecy also applied to einsteinium which is element number 99 and was found by the same team.

During 1953 and into 1954 scientists based at the Nobel Institute of Physics in Stockholm, Sweden bombarded uranium-238 with ions of oxygen-16. Eventually they produced atoms of the isotope fermium-250 which has a half-life of thirty minutes. The isotope found by the American scientists was fermium-255 with a half-life of 20.07 hours.

Fermium is produced today by subjecting elements such as plutonium to a series of neutron collisions followed by beta decays. This is a long process and produces very little of the element.

At least sixteen isotopes of fermium have now been produced. These have masses ranging from 243 to 258. Fermium-257 has the longest half-life at 100.5 days. It decays either by spontaneous fission or to californium-253 by alpha decay.

Not much is known about the chemical properties of fermium owing to the small amount that has been produced. It is a rare earth element of the actinide or actinoid series. It is assumed that fermium would be metallic and it is probably silvery/white or gray in color. No compounds of fermium have currently been made.

With such a lengthy process to produce any atoms of the element combined with their short half-life it is unlikely that fermium will ever have any commercial use. It remains of interest to researchers in the field of man-made elements.