Chemistry : Periodic Table
What is the Modern Periodic Table?
The first major classification of elements was into metals and non-metals. This was followed by Dobereiner's Triads. John Newlands gave the Law of Octaves, which unfortunately was not taken seriously. Mendeleev then gave the law that "the physical and chemical properties of elements are periodic functions of their atomic weights" and arranged elements according to their atomic weights.
The modern periodic table is based on Moseley's law who claimed that atomic number and not atomic mass should be used as the basic property for classification. The horizontal rows in a periodic table are called periods and the vertical columns are called groups. The first column (group 1) of the periodic table is that of alkali metals and the last column (group 18) is that of noble gases. Properties of the elements in the same group are similar.
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Practice Exercise for Chemistry Module on Periodic Table
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