Development of the Periodic Table

... Development of the Periodic Table A necessary requirement to the building of the Periodic Table was the discovery of the individual elements themselves. Although elements such as gold, silver, tin, copper, lead and mercury have been known since antiquity, the first scientific discovery of an element occurred in 1649 when Hennig Brand discovered Phosphorous. During the next 200 years or so, a vast body of knowledge concerning the properties of elements and their compounds was founded by chemists. By 1869, a total of 63 elements, almost half of how many have been discovered today, had been discovered. As the number of known elements grew, scientists began to recognize patterns in properties and began to develop classification schemes into a displayable table, known as the Periodic Table. Law of Triads: In1817 Johann Dobereiner, a German chemist, noticed that the atomic weight of strontium fell midway between the weights of calcium and barium, elements having

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