5 Elements In The Periodic Table
Published on Nov 18, 2015
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5 ELEMENTS IN THE PERIODIC TABLE
By James Mark Lee
LAWRENCIUM
Lawrencium is a synthetic chemical element with chemical symbol Lr (formerly Lw) and atomic number 103. It is named in honor of Ernest Lawrence, inventor of the cyclotron, a device that was used to discover many artificial radioactive elements. A radioactive metal, lawrencium is the eleventh transuranic element and is also the final member of the actinide series. Like all elements with atomic number over 100, lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles. Twelve isotopes of lawrencium are currently known; the most stable is 266Lr with a half-life of 11 hours, but the shorter-lived 260Lr (half-life 2.7 minutes) is most commonly used in chemistry because it can be produced on a larger scale.
History:
In 1958, scientists at the Lawrence Berkeley National Laboratory claimed the discovery of element 102, now called nobelium. At the same time, they also attempted to synthesize element 103 by bombarding the same curium target used with nitrogen-14 ions. A follow-up on this experiment was not performed, as the target was destroyed. Eighteen tracks were noted, with decay energy around (9 ± 1) MeV and half-life around 1⁄4 s; the Berkeley team noted that while the cause could be the production of an isotope of element 103, other possibilities could not be ruled out. While the data agrees reasonably with that later discovered for 257Lr (alpha decay energy 8.87 MeV, half-life 0.6 s), the evidence obtained in this experiment fell far short of the strength required to conclusively demonstrate the synthesis of element 103.[3][4] Later, in 1960, the Lawrence Berkeley Laboratory attempted to synthesize the element by bombarding 252Cf with 10B and 11B. The results of this experiment were not conclusive.[3]
While the lightest (252Lr to 254Lr) and heaviest (266Lr) lawrencium isotopes are produced only as alpha decay products of dubnium (Z = 105) isotopes, the middle isotopes (255Lr to 262Lr) can all be produced by bombarding actinide (americium to einsteinium) targets with light ions (from boron to neon). The two most important isotopes, 256Lr to 260Lr, are both in this range. 256Lr can be produced by bombarding californium-249 with 70 MeV boron-11 ions (producing lawrencium-256 and four neutrons), while 260Lr can be produced by bombarding berkelium-249 with oxygen-18 (producing lawrencium-260, an alpha particle, and three neutrons).
RUTHERFORDIUM
Rutherfordium is a chemical element with symbol Rf and atomic number 104, named in honor of physicist Ernest Rutherford. It is a synthetic element (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known isotope, 267Rf, has a half-life of approximately 1.3 hours.
History:
Rutherfordium was reportedly first detected in 1964 at the Joint Institute of Nuclear Research at Dubna (then in the Soviet Union). Researchers there bombarded a plutonium-242 target with neon-22 ions and separated the reaction products by gradient thermochromatography after conversion to chlorides by interaction with ZrCl4. The team identified spontaneous fission activity contained within a volatile chloride portraying eka-hafnium properties. Although a half-life was not accurately determined, later calculations indicated that the product was most likely rutherfordium-259 (abbreviated as 259Rf in standard notation).
Chemical:
Rutherfordium is the first transactinide element and the first member of the 6d series of transition metals. Calculations on its ionization potentials, atomic radius, as well as radii, orbital energies, and ground levels of its ionized states are similar to that of hafnium and very different from that of lead.
Physical and Atomic:
Rutherfordium is expected to be a solid under normal conditions and assume a hexagonal close-packed crystal structure (c/a = 1.61), similar to its lighter congener hafnium
DUBNIUM
History:
Dubnium was reportedly first discovered in 1968 at the Joint Institute for Nuclear Research at Dubna (then in the Soviet Union). Researchers there bombarded an americium-243 target with neon-22 ions. They reported a 9.40 MeV and a 9.70 MeV alpha-activity and assigned the decays to the isotope 260Db or 261Db:
Dubnium is a chemical element with symbol Db and atomic number 105. It is named after the town of Dubna in Russia, where it was first produced. It is a synthetic element (an element that can be created in a laboratory but is not found in nature) and radioactive; the most stable known isotope, dubnium-268, has a half-life of approximately 28 hours. Glasses is one example of dubnium.
Element 105 is projected to be the second member of the 6d series of transition metals and the heaviest member of group V in the Periodic Table, below vanadium, niobium and tantalum. Because it is positioned right below tantalum, it may also be called eka-tantalum. All the members of the group readily portray their oxidation state of +5 and the state becomes more stable as the group is descended. Thus dubnium is expected to form a stable +5 state. For this group, +4 and +3 states are also known for the heavier members and dubnium may also form these reducing oxidation states. Dubnium is good for creating glasses.
SEABORGIUM
Seaborgium is a synthetic element with symbol Sg and atomic number 106. Its most stable isotope 271Sg has a half-life of 1.9 minutes. A more recently discovered isotope 269Sg has a potentially slightly longer half-life (ca. 2.1 min) based on the observation of a single decay.[citation needed] Chemistry experiments with seaborgium have firmly placed it in group 6 as a heavier homologue to tungsten.
History:
Scientists working at the Joint Institute for Nuclear Research in Dubna, USSR reported their discovery of element 106 in June 1974.[5][6] Synthesis was also reported in September 1974 at the Super HILAC accelerator at the Lawrence Berkeley Laboratory by a joint Lawrence Berkeley/Lawrence Livermore collaboration led by Albert Ghiorso and E. Kenneth Hulet.[7] They produced the new nuclide 263Sg by bombarding a target of 249Cf with 18O ions. 249Cf + 18O→263Sg This nuclide decays by α emission with a half-life of 0.9 ± 0.2 sec.
Much seaborgium chemical behavior is predicted by extrapolation from its lighter congeners molybdenum and tungsten. Molybdenum and tungsten readily form stable trioxides MO3, so seaborgium should form SgO3. The oxides MO3 are soluble in alkali with the formation of oxyanions, so seaborgium should form a seaborgate ion, SgO42−. In addition, WO3 reacts with acid, suggesting similar amphotericity for SgO3. Molybdenum oxide, MoO3, also reacts with moisture to form a hydroxide MoO2(OH)2, so SgO2(OH)2 is also feasible. The heavier homologues readily form the volatile, reactive hexahalides MX6 (X=Cl,F). Only tungsten forms the unstable hexabromide, WBr6. Therefore, the compounds SgF6 and SgCl6 are predicted, and "eka-tungsten character" may show itself in increased stability of the hexabromide, SgBr6. These halides are unstable to oxygen and moisture and readily form volatile oxyhalides, MOX4 and MO2X2. Therefore SgOX4 (X=F,Cl) and SgO2X2 (X=F,Cl) should be possible. In aqueous solution, a variety of anionic oxyfluoro-complexes are formed with fluoride ion, examples being MOF5− and MO3F33−. Similar seaborgium complexes are expected.
BOHRIUM
The last element that I chose
