What is Fermium
Fermium (pronounced as FER-mee-em)  is a synthetic, transuranium, radioactive element  with the symbol Fm  belonging to the family of inner transition metals . It has 18 isotopes with mass numbers ranging from 242 to 259 of which Fm-257 is the most stable isotope with a half-life of 100.5 days [2, 3]. It decays into californium-253 through alpha emission and spontaneous fission .
Where Is it Found
It cannot be found naturally on earth . However, it can be obtained in microgram quantities by the neutron bombardment of plutonium in a nuclear reactor .
History of the Element
Origin of the Name: The element is named after the famous nuclear physicist Enrico Fermi .
Who Discovered it: It was discovered by a team of scientists led by Albert Ghiorso on October 31, 1952 [2, 3].
How was it Discovered
The first isotope of fermium (later named as fermium-255), was found in the nuclear debris after the thermonuclear explosion of the first hydrogen bomb (codenamed Ivy Mike [3, 10]) on an atoll in the Pacific Ocean . It was because uranium-238, the source of heat for the detonation, was exposed to a flux of neutrons during the process and combined with 17 of them to produce Fm-255 that has a half-life of about 20 hours [1, 2].
It was later produced in the laboratory by a group at the Nobel Institute of Stockholm. They bombarded uranium-238 with oxygen nuclei producing fermium-250 with a half-life of 30 minutes .
|Atomic Number||100 |
|CAS Number||7440-72-4 |
|Position in the periodic table||Group: Actinides||Period: 7 ||Block: f |
Properties and Characteristics of Fermium
|Atomic mass||257 atomic mass units [8,9]|
|Mass number||257 |
|Melting point/freezing point||1527°C (2781°F) |
|Boiling point||Unknown |
|State of matter at room temperature (natural state)||Solid [1,2]|
|Hardness||Unknown [12, 15]|
|Oxidation state/Oxidation number||+2, +3 |
Atomic Data of Fermium (Element 100)
|Valence electrons||2 |
|– n||5 |
|– ℓ||3 |
|– m ℓ||1 |
|– m s||-½ |
|Electron configuration (noble gas configuration)||[Rn]5f127s2 |
|– Number of Electrons||100 |
|– Number of Neutrons||157 |
|– Number of Protons||100 |
|– First Energy Level||2 |
|– Second Energy Level||8 |
|– Third Energy Level||18 |
|– Fourth Energy Level||32 |
|– Fifth Energy Level||30 |
|– Sixth Energy Level||8 |
|– Seventh Energy Level||2 |
|Radius of atom|
|– Atomic Radius||2.45 Å |
|– Covalent Radius||1.67 Å |
Uses of Fermium
Due to its minute production and short half-life, it is used for research purposes only .
It is potentially dangerous due to its radioactivity .
- Fermium, along with Einsteinium, was one of the first synthetic elements produced after the testing of a hydrogen bomb [10, 15].
- As the hydrogen bomb testing was top secret, researchers could only publish the discovery of Fm in 1955 after producing it officially in a laboratory [1, 3, 10].
Cost of Fermium
Unavailable since it is not found naturally and only produced in nuclear reactors .