Fermium

Fermium, ₁₀₀Fm

Fermium
Pronunciation	/ˈfɜːrmiəm/ (listenⓘ) ​(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 ↓ — 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 ​(1527 °C, ​2781 °F) (predicted)
Density (near r.t.)	9.7(1) g/cm3 (predicted)
Atomic properties
Oxidation states	+2, +3
Electronegativity	Pauling scale: 1.3
Ionization energies	1st: 629 kJ/mol
Other properties
Natural occurrence	synthetic
Crystal structure	​face-centered cubic (fcc) (predicted)
CAS Number	7440-72-4
History
Naming	after Enrico Fermi
Discovery	Lawrence Berkeley National Laboratory (1953)
Isotopes of fermium
Main isotopes 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 –

Enrico Fermi.

Fermium is a synthetic, radioactive transuranic chemical element that has the symbol Fm and atomic number 100 named after Enrico Fermi.

Chemistry

Scientists can create Fermium by combining plutonium with neutrons at very high speeds and temperatures, but we know little about its chemistry.

It does form the chloride, , and it compares pretty similar to Samarium, the element above it.

History

Albert Ghiorso and other scientists at the University of California, Berkeley first discovered fermium in the fallout from the explosion of the first successful hydrogen bomb test, Ivy Mike, on November 1, 1952 along with another new element, Einsteinium. Because of the Cold War, the US military did not allow the scientists to publish their results in a scientific journal, yet they still conducted other studies and published their research in 1954 and the studies of nuclear fallout were declassified and published in 1955.

A group in the Nobel Institute for Physics in Stockholm also discovered isotopes of this element before the research of the Berkeley scientists was published. However, most agree that the Berkeley scientists were the first to discover fermium.