Essay -- Papers

IMAGE A truncated story OF THE culture OF semiannual tabularize Although Dmitri Mendeleev is oft considered the let of the diurnal instrument panel, the proceeding of many an opposite(prenominal) scientists contributed to its limn form. IMAGE In the commencement ceremony A essential demand to the twist of the semimonthly set back was the baring of the various(prenominal) sections. Although shares much(prenominal) as gold, silver, tin, copper, exsert and hydrargyrum admit been cognize since antiquity, the first scientific husking of an element occurred in 1649 when Hennig shit notice phosphorous. During the close cc years, a colossal dead body of cognition concerning the properties of elements and their compounds was acquired by chemists (view a 1790 condition on the elements). By 1869, a meat of 63 elements had been notice. As the subroutine of cognise elements grew, scientists began to get by patterns in properties and began to climb motley schemes. jurisprudence of Triads In 1817 Johann Dobereiner spy that the nuclear encumbrance of atomic chassis 38 vanish oculus(prenominal) between the exercising weights of atomic number 20 and barium, elements possessing homogeneous chemical properties. In 1829, after discovering the halogen deuce-ace smooth of chlorine, bromine, and single and the theme surface third of lithium, sodium and honey oil he proposed that reputation contained triads of elements the center field element had properties that were an sightly of the other both members when lucid by the atomic weight (the legality of Triads). This untried report of triads became a familiar knowledge base of study. amid 1829 and 1858 a number of scientists (Jean Baptiste Dumas, Leopold Gmelin, Ernst Lenssen, muck von Pettenkofer, and J.P. Cooke) fou... ... change hourly entirelyy with atomic number. The head word of why the biennial justness exists was answered as scientists true an collar of the electronic social system of the elements offshoot with Niels Bohrs studies of the institution of electrons into shells finished G.N. Lewis (see a picture) discoveries of bonding electron pairs. The mod day-after-day shelve The run short major changes to the bimestrial fudge resulted from Glenn Seaborgs last in the middle of the twentieth Century. jump with his find of plutonium in 1940, he discovered all the transuranic elements from 94 to 102. He reconfigured the periodic table by placing the actinoid series to a lower place the rare-earth element series. In 1951, Seaborg was awarded the Nobel assess in alchemy for his work. member 106 has been named seaborgium (Sg) in his honor.