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Thursday 28 February 2013

History Periodic Tabel

HISTORY OF THE PERIODIC TABLE

It was 1649 when the scientist Hennig Brand discovered the jump element, phosphoric and by 1869 a total of 63 elements had been discovered. As the total of elements discovered increased scientists started to see patterns in their properties and they began to form a way of classifying the elements.
Between around 1770 and 1789Antoine Lavoisier wrote the first extensive angle of dip of 33 elements, however, it was discovered posterior on that some were real mixtures and compounds rather than elements.
In 1828, the Swedish chemist Jöns Jacob Berzelius compiled a table of relative atomic weights of all the elements that had been discovered up to this time. Berzelius similarly developed the system of using letters to typify elements which is still used to this day, eg: O is used to represent oxygen.
Johann Dobereiner first noticed in 1817 that the atomic weight of Strontium was surrounded by the atomic weights of calcium and barium which had similar chemical properties. It was this that later led Johann Dobereiner, in 1829 to propose the Law of the Triads, after discovering the halogen and root word metals triad.
The English chemist John Newlands arranged the known elements in order of atomic weights and grouped them into 11 groups according to the similarities in their physical properties.

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In 1864 he proposed the Law of the Octaves where he discovered similarities in pairs of elements that occurred between the first and ninth element and the bet on and the tenth element etc.
Lothar Meyer, in 1869, compiled the periodic table so that the elements were arranged in order of atomic mass so to show elements that had similar chemical and physical properties were grouped to accepther at various intervals in the periodic table.
In 1869, Dmitri Mendeleev also compiled the periodic table with the 63 known elements by organization them in order of ascending atomic weight and sort out together the elements with similar properties. His table left gaps fro elements...If you want to get a full essay, order it on our website: Ordercustompaper.com



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