Essay -- Papers

IMAGE A BRIEF HISTORY OF THE using OF PERIODIC TABLE Although Dmitri Mendeleev is often considered the father of the occasional table, the work of many an(prenominal) scientists contributed to its present form. IMAGE In the Beginning A necessary prerequisite to the turn of events of the periodic table was the stripping of the individual shares. Although elements such as gold, silver, tin, copper, extend and mercury have been known since antiquity, the first scientific discovery of an element occurred in 1649 when Hennig Brand discovered phosphorous. During the next 200 years, a coarse body of knowledge concerning the properties of elements and their compounds was acquired by chemists (view a 1790 article on the elements). By 1869, a total of 63 elements had been discovered. As the number of known elements grew, scientists began to fill out patterns in properties and began to develop classification schemes. Law of Triads In 1817 Johann Dobe reiner noticed that the nuclear weight of strontium fell midway between the weights of calcium and barium, elements possessing corresponding chemical properties. In 1829, after discovering the halogen triad composed of chlorine, bromine, and iodine and the al-Qaida metal triad of lithium, sodium and potassium he proposed that nature contained triads of elements the shopping centre element had properties that were an average of the other two members when ordered by the nuclear weight (the Law of Triads). This new idea of triads became a popular sports stadium of study. Between 1829 and 1858 a number of scientists (Jean Baptiste Dumas, Leopold Gmelin, Ernst Lenssen, Max von Pettenkofer, and J.P. Cooke) fou... ... varied periodically with atomic number. The question of why the periodic law exists was answered as scientists developed an agreement of the electronic structure of the elements beginning with Niels Bohrs studies of the organization of elect rons into shells through G.N. Lewis (see a picture) discoveries of hold fast electron pairs. The Modern Periodic Table The last major changes to the periodic table resulted from Glenn Seaborgs work in the middle of the 20th Century. Starting with his discovery of plutonium in 1940, he discovered all the transuranic elements from 94 to 102. He reconfigured the periodic table by placing the actinide series beneath the lanthanide series. In 1951, Seaborg was awarded the Nobel Prize in chemistry for his work. Element 106 has been named seaborgium (Sg) in his honor.