Only Np, Pu, and Am have uses (very small amounts of the others have been made).
Np:   Component in neutron detection instruments
Pu:   Nuclear weapons, nuclear power, pacemakers
Am:  Source for smoke detectors and portable source of gamma rays

Until 1997, the International Union of Pure and Applied Chemistry (IUPAC) recommended different names for elements 104-109 than those suggested by American Chemical Society (ACS).  IUPAC and ACS currently differ only for elements 105 & 107.

The transuranium elements were named after planets (neptunium & plutonium), places (America, Berkeley, California, Nuclear Institute at Dubna Russia, & Latin word "Hess" for German state), and scientists.  Some scientists are highly recognizable (Einstein #99) or mentioned in freshman chemistry (Bohr #107).  The remainder of this article describes the work of Fermi (#100), Lawrence (#103), Hahn (#105), Seaborg (#106), and Meitner (#109).

Enrico Fermi (1901-1954)
In 1934, while professor of physics at the University of Rome, Fermi bombarded a variety of elements with neutrons. He discovered that slow moving neutrons were especially effective in producing radioactive atoms. In 1938 Fermi was awarded the Nobel Prize in physics for identification of new radioactive elements produced by neutron bombardment and for his discovery of nuclear reaction effected by slow neutrons. He was given permission by the Fascist government of Mussolini to travel to Sweden to receive the award; Fermi and his wife left Italy never to return. Unknown to Fermi and the Nobel Prize Committee, the "new elements" Fermi characterized weren't new but a result of splitting uranium.
Enrico Fermi settled in the United States and devised the crucial experiment on December 2, 1942 that produced the chain reaction needed to make an atomic bomb. During World War II he became part of the team that developed the atomic bomb and later pioneered research using high energy particles.

Ernest Lawrence (1901-1958)
When Lawrence joined the physics faculty at Berkeley in 1928, the hottest topic in physics was bombarding the atom's nucleus to see what new particles it might produce.  Lawrence read about a theoretical linear accelerator that was too long to be practicle.   Lawrence knew that a magnetic field would deflect the charged particles into a curved path. By making the particles go in a spiral, he could boost the energy bit by bit each time they circled an electrode  The university gave Lawrence approval and in 1930 the cyclotron was born.  This new tool launched the modern era of high-energy physics.  In 1961, element 103 was and named in his honor.

Otto Hahn (1879-1968)
In 1938, Otto Hahn repeated Fermi's experiments of bombarding uranium with neutrons.  Hahn and co-worker Fritz Strassmann discovered three isotopes of barium had been produced.  This was incredible because the mass of barium is about half of uranium and no known reaction could explain such a huge change.  Hahn, a chemist, could not offer an explanation.  He wrote to Lise Meitner, his longtime collaborator, describing his findings and asking "Perhaps you can suggest some fantastic explanation," which she explained as nuclear fission. Nevertheless, despite the contributions of Strassmann and Meitner, it was Hahn who was awarded the 1945 Nobel Prize in chemistry for the discovery.  Unfortunately, Hahn was not at the awards ceremony to receive his prize. At the time he learned of the award, he was being held by the British who were seeking information from him about the failed German effort to develop an atomic bomb. As the chairman of the Nobel Committee for Chemistry reported "Professor Hahn has informed us that he is regrettably unable to attend this ceremony."

Glenn Seaborg (1912-1999)
After graduating from UCLA with a degree in chemistry in 1934, Seaborg did graduate work at Berkeley under Gilbert Lewis (acid-base theory) and completed his Ph.D. in 1937 under Ernest Lawrence (fast neutrons).  During World War II he headed the group which devised the chemical extraction processes used in the production of plutonium for the Manhattan Project.  Besides plutonium, Seaborg discovered americium, curium, berkelium, californium, einsteinium, fermium, mendelevium and nobelium.  In 1944 Seaborg formulated the actinide series placing elements 90-103 at the bottom of periodic table.  For  discoveries of the transuranium elements, Seaborg was awarded the 1951 Nobel Prize in chemistry.  Seaborgium, atomic number 106, represents the first time an element had been named after a living person.

Lise Meither (1878-1968)
Meitner, first woman to receive doctorate in physics from the University of Vienna, began work in 1907 with Otto Hahn at the University of Berlin.  They studied radioactive substances for the next 30 years; she did the physics and he the chemistry. Together and independently they achieved important results in the new field of nuclear physics including techniques for purifying radioactive material, discovering the element protactinium (#91), and explaining how gamma rays eject orbital electrons.
Leaving Germany in 1938 because of her Jewish ancestry, Meitner obtained an appointment at the Physics Institute in Stockholm.  Otto Hahn, who was still in Germany, repeated some of Fermi's early experiments. He wrote Meitner reporting how bombarding uranium with neutrons produced radioactive barium.  Meitner, realizing that uranium had been split, made calculations showing the formation of barium, krypton, additional neutrons, and energy.  When Leo Szilard at Columbia University discovered that more neutrons were produced than used in the fission, he convinced Einstein to write President Franklin Roosevelt (see letter) to set up program for creating Atomic Bomb.  The first fission bomb resulted from bombarding ²³⁵U with a neutron to form ²³⁶U; ²³⁶U  immediately barium, krypton, 3 additional neutrons, and enormous amount of energy.  The 3 neutrons can strike three ²³⁵U nuclei and generate 9 neutrons, which can generate 27 neutrons, and so on (chain reaction).
       ²³⁵U  + ₀n ® ²³⁶U ® ¹⁴¹Ba  +  ⁹²Kr  +  3 ¹n  + energy

Meitner & Hahn named the process "nuclear fission" and reported the results in the journal Nature (1939).  In 1945 the Nobel Prize in Chemistry was awarded to Otto Hahn for the discovery of nuclear fission.  Probably due to Meitner's leaving Germany, the Nobel committee failed to understand her part in the work.  Lise Meitner was probably the most significant woman scientist of the 20th century.

Alıntı: http://web.fccj.org/~ethall/uranium/uranium.htm

Hiçbir yazı/ resim  izinsiz olarak kullanılamaz!!  Telif hakları uyarınca bu bir suçtur..! Tüm hakları Çetin BAL' a aittir. Kaynak gösterilmek şartıyla  siteden alıntı yapılabilir.

The Time Machine Project © 2005 Cetin BAL - GSM:+90  05366063183 -Turkiye/Denizli 

Ana Sayfa /index /Roket bilimi / E-Mail /CetinBAL/Quantum Teleportation-2   

Time Travel Technology /Ziyaretçi Defteri /UFO Technology/Duyuru

Kuantum Teleportation /Kuantum Fizigi /Uçaklar(Aeroplane)

New World Order(Macro Philosophy) /Astronomy