Atomic Structure, Moles and Periodicity

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Atomic structure, Moles and Periodicity The Periodic Table is guidance or map to access different elements specific information, such as: atomic mass, isotopic richness, nuclear spins, electronic configuration and the position of elements belong to which group and period in table. Over the past decades there were many Scientifics which help to improvement of Periodic table but few of them made the most influence and contribution on Periodic table such as : Johann Dobereiner ,John Newlands , Dmitri Mendeleev and Henry Moseley. Law of Triads The development of Periodic table begins with the German chemist Johann Dobreeiner. He collected similar elements together. His triads were groups of three similar elements for example: Calcium, Strontium and Barium in one group. He noticed that the relative atomic mass of middle element is the average of the two others elements. For instance example atomic mass of Strontium is 88, so if you add atomics mass of Calcium which is 40 and Barium which is 137 and divided by 2 you get 88 which is the exactly same atomic mass of Strontium. Law of Octaves English chemist John Newlands started to put around the 60 known elements in order of increasing atomic mass. He noticed after space of eight elements, similar physical and chemical properties reappeared and each element was similar to the element eight place further on. One problem with his table, he put the Iron in same group of Oxygen and Sulphur which are two non metals. Then Russian scientist, Dimitri Mendeleev continues with John Newlans's way. He did the same thing as Newlands and he put the elements in order of increasing atomic mass but he did some extra things that made his table more successful , and produced a much better table ... ... middle of paper ... ...o.uk/schools/gcsebitesize/science/edexcel/patterns/periodictablerev5.shtml. Last accessed 13 December 2009. . (2009). Periodic table. Available: http://www.chemicool.com/. Last accessed 13 December 2009. Dr Edwin Thall. (-). Development of periodic table.Available: http://mooni.fccj.org/~ethall/period/period.htm. Last accessed 13 December 2009 -. (-). History of periodic table. Available: http://en.wikipedia.org/wiki/History_of_the_periodic_table. Last accessed 12 December 2009. -. (-). History of periodic table. Available: http://www.rsc.org/education/teachers/learnnet/periodictable/. Last accessed 13 December 2009. Ann and Patrik Fullick (1994). Chemistry. London: Heinemann educational. -. Catrin Brown and Mick Ford (2008). Standard level chemistry. London: British library cataloguing data. – Number of words: 1,145 Works Cited www.bbc.co.uk

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