you are know that matter can exist in the form of elements, compounds and mixtures. when element were discovered scientists adopted different ways to classify them. in earlier days very few elements were known. at that time they were classified as metals and non-metals on the basis of their properties. some elements showed properties of both metals and non-metals and they could not be placed in any of the two classes.to overcome these difficulties, scientists tried to find out some pattern or regularity in the properties of elements.
1.1-Newlands' octaves
newlands' law states that "when the elements are arranged in an increasing order of their atomic masses, the properties of the eights elements are similar to the first."
1.2-mendeleeves's periodic table
the physical and chemical properties of elements are a periodic function of their atomic masses.
the tabular arrangement of the elements based on the periodic law is called the mendeleev's periodic table.
1.3-modern periodic table
classification of elements
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