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Unformatted text preview: Even before we had this nice understanding of the atomic structure, scientists had identified certain substances as elements . So there were many attempts to arrange the known elements so that there were some correlations between their known properties. The first reasonably successful attempt was made by Dimitri Mendeleev in 1869. He had the idea of arranging elements in order of increasing atomic mass , and, most importantly, found that elements with similar chemical and physical properties occured periodically . He placed these similar elements under each other in columns. In 1914, Henry Moseley determined that a better arrangement was in order of increasing atomic number , giving us the periodic table we have today. We can define the periodic table as an arrangement of elements in order of increasing atomic number placing those with similar chemical and physical properties in columns.order of increasing atomic number placing those with similar chemical and physical properties in columns....
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