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While studying the weight of some elements, Döbereiner noticed that some groups of three elements had similar properties. For example, Lithium, sodium and potassium were also a triad.
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Tobolsk, Siberia.
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Newlands observed that if the elements were arranged in order of increasing atomic weight each eighth element would have similar chemical properties. This pattern was called the “law of octaves”. However, pattern only worked with the first octaves.
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The first version of the periodic table was created and published by Dmitrii Ivanovich Mendeleev on February 17, 1869. In this chart 63 elements were arranged based on their atomic masses and chemical characteristics. While organizing the table in order of increasing atomic number, Mendeleev discovered that there was a recurring pattern in the properties of the elements. This pattern was named "Periodic law".
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One of the most impressive characteristic of the periodic law was that Mendeleev predicted the existence and the characteristics of several unknown elements. For example, Mendeleev inferred the existence of Gallium, he called it eka-aluminum.
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St. Petersburg, Russia
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A synthetic chemical element of of the periodic table, atomic number 101 was named Mendelevium
