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Though topping the periodic table's alkali metal column, hydrogen is not, under ordinary conditions, an alkali metal itself. In 1935, however, Nobel Prize-winning physicist Eugene WignerEugene Paul Wigner ( Hungarian Wigner Pal Jeno) ( November 17, 1902 January 1, 1995) was a Hungarian- American physicist and mathematician. He was one of a generation of physicists of the 1920s who remade the world of physics. It was a collection of peopl predicted that under immense pressurePressure (symbol: p is a measure of force per unit area. where p is the pressure F is the force A is the area Often F is taken to be the of the magnitude of the mean vector force normal to the surface of area A upon which it exerts; the "surface" not nece, hydrogen atomFor alternative meanings see atom (disambiguation). An atom is a microscopic structure found in all ordinary matter around us. Atoms are composed of 3 types of subatomic particles: electrons, which have a negative charge; protons, which have a positive chs would indeed join their first period kin, relinquishing their proprietary hold over their electrons.
The pressures required made experimental verification elusive. In March 19961996 was a leap year starting on Monday (see link for calendar), and was designated the International Year for the Eradication of Poverty''. Events January January 5 Hamas operative Yahya Ayyash is killed by an Israeli-planted booby-trapped cell phone Jan, however, a group of scientists at Lawrence Livermore National LaboratoryThe Lawrence Livermore National Laboratory (LLNL is a United States Department of Energy national laboratory, managed by the University of California, in Livermore, California. Along with Los Alamos National Laboratory, it is one of the USA's two laborato reported that they had serendipitouslySerendipity is finding something unexpected and useful while searching for something else entirely. For instance, the discovery of the antibacterial properties of penicillin by Alexander Fleming is said to have been serendipitous, because he was merely cl produced - for about a microsecondA microsecond is an SI unit of time equal to one millionth (10-6) of a second. It is often used for measuring things like atomic and chemical reactions, which occur in normally imperceptible lengths of time. Its symbol is s . See also 1 E-6 s for comparis, and at temperatures of thousands of kelvins and pressures of over a million atmospheres - the first identifiably metallic hydrogen, ending the 60-year search.
The Lawrence Livermore team did not expect to produce metallic hydrogen, as they were not using solid hydrogen, thought to be necessary, and were working above the temperatures specified by metallization theory ; furthermore, in previous studies in which solid hydrogen was compressed inside diamond anvils to pressures of up to 2.5 million atmospheres, detectable metallization did not occur. The team sought simply to measure the less extreme conductivity changes that they expected to take place.
The researchers used a 1960s-era light gas gun originally used in guided missile studies to shoot an impactor plate into a sealed container containing a half- millimetre-thick sample of liquid hydrogen. First, at one end of the gun, the hydrogen was cooled to about 20 K inside a container that included a battery connected by wires to a Rogowski coil and an oscilloscope; the wires also touched the surface of the hydrogen in several places, so the apparatus could be used to measure and record its electrical conductivity. At the opposite end, up to 3 kg (7 lb) of gunpowder was ignited, and the resulting explosion pushed a piston through a pump tube, compressing the gas inside. Eventually the gas reached a pressure high enough to throw a valve at the far end of the chamber. Entering the thin "barrel", it propelled the plastic-covered metal impactor plate into the container at up to 8 km/s (18,000 mph), compressing the hydrogen inside.
The scientists were stunned to find that as pressure rose to 1.4 million atmospheres, the electronic energy band gap (a measure of electrical resistivity) fell to almost zero.
The electronic energy band gap of hydrogen in its uncompressed state is about 15 eV, making it an insulator, but as pressure rises to almost unimaginable heights, the band gap gradually falls to 0.3 eV. Because 0.3 eV are provided by the thermal energy of the fluid (remember, the pressure increased tremendously and the Law of Charles and Gay-Lussac
so the temperature became about 3000 K), the hydrogen can at this point be considered fully metallic.
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