Element Uranium, U, Actinide or Actinoid
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Uranium History
Uranium had been discovered in 1789 by the German chemist Martin Klaproth who called this element uranium after the last planet to have been discovered 8 years before that. In fact the substance obtained by Klaproth was the oxide of a yet-undiscovered element which actually was separated by Eugene-Melchior Peligot in 1841. From that time and to the 20th century uranium did not have that significance which it has today, although many of its physical properties as well as the atomic mass and density had been found out.
In 1896 the French scientist Henri Becquerel discovered the radioactive property of uranium by exposing a photographic plate to it. This discovery encouraged physicists to initiate the radioactivity investigations, and in 1898 Pierre Curie and Maria Skłodowska-Curie separated salts of such radioactive element as polonium and radium; meanwhile E. Rutherford, F. Soddy, K. Fajans and many other scientists developed the theory or radioactive fission putting the foundation of modern nuclear chemistry and nuclear power industry.
Uranium Occurrence
Uranium is a member of actinide (or actinoid) group of chemical elements is a specific element of granite layer and sedimentary shell of the Earth crust. The crustal abundance is 2.5x10-4% by mass; concentration in acidic igneous rocks is 3.5x10-4%, 3.2x10-4% in clays and slates, and 5x10-5% in basic rocks and 3x10-7% in ultrabasic rocks. Uranium actively migrates in cold and hot, alkaline and neutral water, in the form of simple and complex, especially carbonate ions. Redox reactions are very important in uranium geochemistry, because its compounds are highly soluble in oxidizing water environment and very poorly soluble in reducing environment (for instance, in hydrosulfuric). Minute amounts (10-5%) of uranium are found in plant, animal and human tissues and 1.5x10-5% in plant cinder if the concentration in soil is 1x10-4%. Uranium is accumulated mostly by mushrooms and seaweed; the latter actively participates in biogenic chain uranium migration by scheme "water -> seaweed -> fish -> human".
Uranium gets into human organism with food and water, through gastrointestinal tract (1% highly soluble and poorly soluble of the whole amount), respiratory system (50% and 20% correspondingly)., skin and mucosae. The most uranium depots (accumulation locations) are the spleen, kidneys, liver, and, if hardly soluble compounds are breathed, in the lungs and bronchus-lung lymphatic nodes. The circulation of uranium compounds in the form of carbonates and protein complexes) in blood does not take long time. The concentration in tissues does not exceed 10-7%.
Uranium Neighbours
Element Periodic Table | | | |