The History of the Periodic Table.

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The History of the Periodic Table.

        The organization of the modern periodic table is perhaps one of the most significant tasks undertaken in chemistry. It is the purpose of this essay to introduce the history of the periodic table and briefly discuss how and who modified it.

 

Today there are 109 known elements, and these are usually displayed in the form of a matrix called a periodic table. The term periodic came from the regular occurrence of certain chemical properties in the list of known elements when these are arranged in order of increasing relative mass.

        The rectangular periodic table is familiar to anybody who gas ever been in a science laboratory or classroom.

 Several European scientists created this ingenious functional grouping of the chemical elements in the decade of the 1860’s.

In 1863, a 44-year-old French geologist, A. E. Béguyer de Chancourtois created a list of the elements arranged by increasing atomic weight. The list he created was wrapped around a cylinder so that several sets of similar elements lined up, creating the first geometric representation of the periodic law.

 

        In England, a 32-year-old analytical chemist John A. R. Newlands was also wrapping the elements, noting that the chemical groups repeated every eight elements. He named this octave rule, and compared it to a musical scale. Some less observant members of the English Chemical Society considered this absurd, so his work was ignored for years.

        Chemists Dmitri I. Mendeleev, a Russian, and German Lothar Meyer were working independently in 1868 and 1869 on the arrangement of the elements into seven columns, corresponding to various chemical and physical properties.

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The atomic weight, relative atomic mass, is roughly proportional to atomic number because valency, which manifests itself in the chemical composition, is based on the outermost electrons of an atom; Mendeleev had chosen the two properties that in his day most nearly reflected the fundamental principles on which the table today is based.

Mendeleev completed his version of the table in 1869, when 63 known elements existed. As Mendeleev said, “If all the elements can be arranged in order of their atomic weights a periodic repetition of properties is obtained. Mendeleev arranged the elements according to weight, and then proceeded ...

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