Fermium

Fermium, ₁₀₀Fm

Fermium
Pronunciation	/ˈfɜːrmiəm/ ​(FUR-mee-əm)
Mass number	[257]
Fermium in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Er ↑ Fm ↓ (Upq) einsteinium ← fermium → mendelevium
Atomic number (Z)	100
Group	f-block groups (no number)
Period	period 7
Block	f-block
Electron configuration	[Rn] 5f12 7s2
Electrons per shell	2, 8, 18, 32, 30, 8, 2
Physical properties
Phase at STP	solid (predicted)
Melting point	1800 K ​(1500 °C, ​2800 °F) (predicted)
Density (near r.t.)	9.7(1) g/cm3 (predicted)[1][a]
Atomic properties
Oxidation states	+2, +3
Electronegativity	Pauling scale: 1.3
Ionization energies	1st: 629 kJ/mol [2]
Other properties
Natural occurrence	synthetic
Crystal structure	​face-centered cubic (fcc) (predicted)[1]
CAS Number	7440-72-4
History
Naming	after Enrico Fermi
Discovery	Lawrence Berkeley National Laboratory (1953)
Isotopes of fermium v e
Main isotopes[3] Decay abun­dance half-life (t1/2) mode pro­duct 252Fm synth 25.39 h SF – α 248Cf 253Fm synth 3 d ε 253Es α 249Cf 255Fm synth 20.07 h SF – α 251Cf 257Fm synth 100.5 d α 253Cf SF –
Category: Fermium view talk edit | references

Fermium is a synthetic chemical element; it has 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 fermium metal has not yet been prepared.^[4] A total of 20 isotopes are known, with ²⁵⁷Fm being the longest-lived with a half-life of 100.5 days.

It was discovered in the debris of the first hydrogen bomb explosion in 1952, and named after Enrico Fermi, one of the pioneers of nuclear physics. Its chemistry is typical for the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. Owing to the small amounts of produced fermium and all of its isotopes having relatively short half-lives, there are currently no uses for it outside basic scientific research.

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