Fermium is a synthetic element with the symbol Fm and atomic number 100. It is an actinide and the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure Fm metal has not yet been prepared.
It was then identified in December 1952 by Albert Ghiorso and co-workers at the University of California at Berkeley. They discovered the isotope 253Es (half-life 20.5 days) that was made by the capture of 15 neutrons by uranium-238 nuclei – which then underwent seven successive beta decays.
It is found in very small quantities and all of its isotopes have very short lives, there is no commercial use for the element. The scientists make use of this element in their research in expanding their knowledge on the rest of the periodic table.
Characteristics of Fermium
- The most stable isotope of Fermium, that is fermium-257 has a half-life of around 100.5 days.
- The isotope can be decayed into californium-253 with alpha decay or through spontaneous fission.
- The chemistry of fermium has only been studied in solution using tracer techniques, and no solid compounds have been prepared. Under normal conditions, fermium exists in solution as the Fm3+ ion, which has a hydration number of 16.9 and an acid dissociation constant of 1.6×10−4 (pKa = 3.8).
- Fm3+ forms complexes with a wide variety of organic ligands with hard donor atoms such as oxygen, and these complexes are usually more stable than those of the preceding actinides
- It also forms anionic complexes with ligands such as chloride or nitrate and, again, these complexes appear to be more stable than those formed by einsteinium or californium.
- Fermium(III) can be fairly easily reduced to fermium(II).