Fermium is a synthetic element with symbol Fm and atomic number 100. It is a member of the actinide series. It is 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 fermium metal has not yet been prepared.
Three reasons Fermium stands out
- 1
Named after Italian-American physicist renowned for creating the world's first artificial nuclear reactor.
- 2
Like element 99, it was discovered hidden in the fallout from the first hydrogen bomb test in 1952.
- 3
It can only be produced in microscopic quantities, making detailed study of its properties extremely difficult.
The heaviest element made by neutron capture
Fermium also emerged from analysis of Ivy Mike fallout. It is the heaviest element that can be built by successive neutron captures in quantities large enough for chemical study; heavier nuclei tend to fission before the chain can continue. No weighable sample of fermium has been produced.