Science: History of The Periodic Table

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Four-hundred years ago, scientists began identifying substances now know as elements. They began recognising patterns in the properties as the number of know elements grew, leading to the beginning of classification schemes that would come to devise the periodic table as we know it today ("The Periodic Table", n.d.). In 1789, French chemist Antoine-Laurent de Lavoisier (1743-93) separated 33 substances he considered elements -including light (now know not to exist as an element) and a liquid called ‘Caloric’ (now known not to exist) (Chemical Heritage Foundation, n.d.)- into metals, non-metals and ‘earths’ (Linstead, 2012, p. 115-116). In 1869 Dmitri Ivanovich Mendeleev a Russian chemist (1834-1907) constructed the first accepted version of the modern periodic table (Linstead, 2012, p. 115-116) wher each element had its own box, grouped accordingly horizontal by the atomic mass and vertical in reference to similar chemical properties. Later realising he had incorrectly placed elements Mendedleev moved them where he believed resemblances suggested they should be positioned. Mendeleev left gaps in his model for many undiscovered elements where he predicted they would go according to the knowledge he had acquired ("periodic table history", n.d.). He was also successful in working out the ‘periodic law’- “law stating that many of the physical and chemical properties of the elements tend to recur in a systematic manner with increasing atomic number. Progressing from the lightest to the heaviest atoms, certain properties of the elements approximate those of precursors at regular intervals of 2, 8, 18, and 32.” ("PERIODIC LAW", n.d.) first published in papers of 1869 ("Julius Lothar Meyer and Dmitri Ivanovich Mendeleev | Chemical Heritag... ... middle of paper ... ...tance-of-chlorine-in-human-body.html Uses of Sodium | Uses Of. (n.d.). Retrieved from http://www.usesof.net/uses-of-sodium.html Why do we need salt? (n.d.). Retrieved from http://www.rsc.org/get-involved/hot-topics/Salt/do-we-need-salt.asp Why Is Sodium Important to the Body - Ask.com. (n.d.). Retrieved from http://www.ask.com/question/why-is-sodium-important-to-the-body Wikipedia (n.d.). Helium hydride ion - Wikipedia, the free encyclopedia. Retrieved April 26, 2014, from http://en.wikipedia.org/wiki/Helium_hydride_ion Wikipedia (n.d.). International Union of Pure and Applied Chemistry - Simple English Wikipedia, the free encyclopedia. Retrieved April 25, 2014, from http://simple.wikipedia.org/wiki/International_Union_of_Pure_and_Applied_Chemistry Your Dictionary (n.d.). Ionic Bond Examples. Retrieved from http://examples.yourdictionary.com/ionic-bond-examples.html

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