Transuranic elements

Transuranic elements (uranium elements, transuranes) - radioactive chemical elements located in the periodic system of elements of D. I. Mendeleev behind uranium , that is, with an atomic number higher than 92.

Elements with an atomic number greater than 100 are called transfermium elements . Eleven of the known transuranic elements (93-103) belong to the number of actinides . Transuranic elements with an atomic number of more than 103 are called transactinoids , more than 120 are called superactinoids .

All known isotopes of transuranic elements have a half-life significantly less than the age of the Earth . Therefore, although the theory of the island of stability, and so-called. The magic nuclei of the shell structure allow the possibility of a long-lived and stable existence even of superheavy transactinoids, the known transuranic elements are practically absent in nature and are obtained artificially through various nuclear reactions . Elements up to and including fermium are formed in nuclear reactors as a result of neutron capture and subsequent beta decay .

Transfermium elements are formed only as a result of nuclear fusion . For their production, target nuclei of heavy elements are bombarded with projectile nuclei obtained at accelerators ^{[1] [2]} .

The first of the Np neptunium transuranium elements (serial number 93) was obtained in 1940 by neutron bombardment of uranium . It was followed by the discovery of plutonium (Pu, bp 94), americium (Am, bp 95), curium (Cm, bp 96), berkelium (Bk, bp 97), California ( Cf, bp 98), Einsteinia (Es, bp 99), fermium (Fm, bp 100), mendelevia (Md, bp 101), nobelium (No, bp 102) and Lawrence (Lr, bp 103). As of 2016 , transactinoids with serial numbers 104–118 have also been synthesized: Rutherfordium (Rf, 104), Dubnium (Db, 105), Seaborgium (Sg, 106), Boron (Bh, 107), Hassium (Hs, 108 ), Meitnerium (Mt, 109), Darmstadtium (Ds, 110), X-ray (Rg, 111), Copernicus (Cn, 112), Nichonium (Nh, 113), Flerovium (Fl, 114), Muscovy (Mc, 115) Livermorium (Lv. 116), Tennessin (Ts. 117), Oganeson (Og, 118). Attempts have also been made to synthesize the following superheavy transuranic elements, including statements about the synthesis of the unbiquadium element (124) and indirect evidence of the elements of unbinylium (120) and unbighexia (126), which have not yet been confirmed.

The chemical properties of light transuranic actinides, obtained in weight quantities, have been studied more or less fully; transfermium elements (Md, No, Lr, and so on) are poorly studied due to the difficulty of production and short lifetimes. Crystallographic studies, the study of the absorption spectra of salt solutions, the magnetic properties of ions and other properties showed that elements with bp 93-103 - analogues of lanthanides . Of all the transuranium elements, plutonium nuclide ²³⁹ Pu has found the greatest use as nuclear fuel.

The first transuranic elements were synthesized in the early 40s of the 20th century at the Lawrence Berkeley National Laboratory ( USA ) by a group of scientists led by Edwin Macmillan and Glenn Seaborg who were awarded the Nobel Prize for the discovery and study of these elements. The synthesis of new transuranic elements and isotopes was also carried out at the Livermore National Laboratory in the USA , the Joint Institute for Nuclear Research in the USSR / Russia ( Dubna ), the Helmholtz European Center for the Study of Heavy Ions in Germany , the Institute of Physicochemical Research in Japan and other laboratories ^{[3] [4]} . In recent decades, international teams have been working on the synthesis of elements in American, German and Russian centers.

The search for superheavy transuranic elements in nature has not yet been crowned with success. The discovery of the element of sergenium (108) in the Cheleken lands in the early 1970s. has not been confirmed. In 2008, the discovery of the ecatorium-unbibium element (122) in natural thorium samples was announced ^[5] , however, this statement is currently disputed based on recent attempts to reproduce data using more accurate methods. In 2011, Russian scientists reported the discovery of traces of collisions with particles with atomic numbers from 105 to 130 in meteorite material, which may be indirect evidence of the existence of stable superheavy nuclei ^[6] .