Hassium

Hassium, ₁₀₈Hs

Hassium
Pronunciation	/ˈhæsiəm/ ⓘ[1] ​(HASS-ee-əm)
Mass number	[271] (data not decisive)[a]
Hassium 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 Os ↑ Hs ↓ — bohrium ← hassium → meitnerium
Atomic number (Z)	108
Group	group 8
Period	period 7
Block	d-block
Electron configuration	[Rn] 5f14 6d6 7s2[4]
Electrons per shell	2, 8, 18, 32, 32, 14, 2
Physical properties
Phase at STP	solid (predicted)[5]
Density (near r.t.)	27–29 g/cm3 (predicted)[6][7]
Atomic properties
Oxidation states	common: (none) (+3), (+4), (+6), (+8)[8]
Ionization energies	1st: 730 kJ/mol 2nd: 1760 kJ/mol 3rd: 2830 kJ/mol (more) (predicted)[9]
Atomic radius	empirical: 126 pm (estimated)[10]
Covalent radius	134 pm (estimated)[11]
Other properties
Natural occurrence	synthetic
Crystal structure	​hexagonal close-packed (hcp) (predicted)[5]
CAS Number	54037-57-9
History
Naming	after Hassia, Latin for Hesse, Germany, where it was discovered[12]
Discovery	Gesellschaft für Schwerionenforschung (1984)
Isotopes of hassium v e
Main isotopes[13] Decay abun­dance half-life (t1/2) mode pro­duct 269Hs synth 12 s α 265Sg 270Hs synth 7.6 s α 266Sg 271Hs synth 46 s α 267Sg 277mHs synth 130 s SF –
Category: Hassium view talk edit | references

Hassium is a synthetic chemical element; it has symbol Hs and atomic number 108. It is highly radioactive: its most stable known isotopes have half-lives of approximately ten seconds.^[a] One of its isotopes, ²⁷⁰Hs, has magic numbers of protons and neutrons for deformed nuclei, giving it greater stability against spontaneous fission. Hassium is a superheavy element; it has been produced in a laboratory in very small quantities by fusing heavy nuclei with lighter ones. Natural occurrences of the element have been hypothesised but never found.

In the periodic table of elements, hassium is a transactinide element, a member of the 7th period and group 8; it is thus the sixth member of the 6d series of transition metals. Chemistry experiments have confirmed that hassium behaves as the heavier homologue to osmium, reacting readily with oxygen to form a volatile tetroxide. The chemical properties of hassium have been only partly characterized, but they compare well with the chemistry of the other group 8 elements.

The principal innovation that led to the discovery of hassium was the technique of cold fusion, in which the fused nuclei did not differ by mass as much as in earlier techniques. It relied on greater stability of target nuclei, which in turn decreased excitation energy. This decreased the number of neutron ejections during synthesis, creating heavier, more stable resulting nuclei. The technique was first tested at the Joint Institute for Nuclear Research (JINR) in Dubna, Moscow Oblast, Russian SFSR, Soviet Union, in 1974. JINR used this technique to attempt synthesis of element 108 in 1978, in 1983, and in 1984; the latter experiment resulted in a claim that element 108 had been produced. Later in 1984, a synthesis claim followed from the Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Hesse, West Germany. The 1993 report by the Transfermium Working Group, formed by the International Union of Pure and Applied Chemistry and the International Union of Pure and Applied Physics, concluded that the report from Darmstadt was conclusive on its own whereas that from Dubna was not, and major credit was assigned to the German scientists. GSI formally announced they wished to name the element hassium after the German state of Hesse (Hassia in Latin), home to the facility in 1992; this name was accepted as final in 1997.

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