Papers by Abdulrahman tebyan
Organizational Designs and Structure., 2021
when you want to make an organization, you need to know about organizational structure and how it... more when you want to make an organization, you need to know about organizational structure and how it works.
Why Lithium is so important in the World? , 2020
ithium is the third element on the periodic table and the first element in the alkali metal group... more ithium is the third element on the periodic table and the first element in the alkali metal group it has atomic mass of 6.94 g/mol, an atomic radius of 1.33 Å, a melting point of 180.5 ℃ and a boiling point of 1342℃. With a density of just 0.534 g/cm 3 , lithium metal floats in water even as it reacts. Lithium has a hardness of 0.6 on the Mohr scale, is softer than talc (Mg Si O (OH)), the softest mineral on the Mohr scale (talc hardness = 1). Lithium is harder than carbon = 0.5, caesium =0.5, and sodium = 0.5 but softer than lead = 1.5 [1]. Lithium has the highest specific heat capacity (at 25 ℃) of any solid element at 3.56 J/g K. Lithium is the most polarising of all the alkali metals and more electronegative than H so it can accumulate chemical energy very efficiently. At a pressure in excess of 40 gigapascals (400,000 atmospheres) lithium becomes a superconductor There are several radioisotopes of lithium ( 4 Li to 12 Li). Their half-lives range from 9 x 10 -23 s for 4 Li to 8 x 10 -1 s for 8 Li. Naturally occurring lithium exists as the tow stable isotopes 6 Li (at 7% abundance) and Li (at 93% abundance) . Lithium has a single valence electron on its outer shell which is freely given up for reaction to from a variety of compounds . The highly reactive nature of lithium (the least reactive of the alkali metals) towards oxygen, a trait it shears with other group 1 alkali metals, means that it never occurs as a pure metal in nature, instead, it occurs as various salts and minerals. The comical history of lithium began with the characterisation of the aluminosilicate minerals petalite (LiAlSi4O10) and spodumene (LiAlSi2O6). They were discovered at the start of the 18 th century be the Brazilian statesman and naturalist Josè Bonifacio de Andrade e Silva the island of Utö, near Stockholm, Sweden . In 1817 the Swedish chemist Johan August Arfwedson discovered a previously unknown element in the new mineral petalite. Arfwedson was working at the time for another Swedish chemist, Baron Jöns Jacob Berzelius. Lithium, according to the author Berzelius (1964) (who coincidentally sheares the same name as Jöns Jacob Berzelius) formed compounds similar to those of sodium and potassium , although lithium's carbonate and hydroxide forms are less soluble in water and alkaline . Together the tow chemists named the mysterious element lithion/litaina from the Greek for stone. Arfwedson went on to discover lithium in lepidolite (K (Li, Al)3(Al, Si,Rb)4O10(F, OH)2). In 1818 Christian Gottlieb Gmelin a colleague of Arfwedson was the first to observe that lithium salts, when exposed to flames, gave off an intense red flame . Although Arfwedson had discovered the element he never managed to isolated pure metallic lithium. In 1821, the English chemist William Thomas Brand, a colleague of Sir Humphary Davy, obtianed lithium by the electrolysis of lithium oxide . In 1855, the German chemist Robert Wilhelm Eberhard Bunsen and English chemist Augustus Matthiessen isolated lithium from lithium chloride be electrolysis . Their production method was later commercialised by the German company Matllgesellschaft AG (1923), who produced metallic L lithium electrolytically from a mixture of 55% lithium chloride and 45% potassium chloride at a temperature of 450℃ [9].
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Papers by Abdulrahman tebyan