Periodic Classification of Elements: Today 114 elements are known to us and all of them have different properties. The earliest attempt to classify then known elements into groups as Metals and Non-metals. Dobereiner’s Traids: In 1817, Joham Walfgang Dobereiner, a German chemist tried to arrange the elements with similar properties into groups. He identified some groups having 3 elements each and named these groups “Triads” According to Dobereiner- when three elements in triads were taken in order of increasing Atomic masses the atomic mass of the middle element was roughly the average of the atomic masses of the other two elements. Newland’s Law of Octaves: Newland’s arranged the then known elements in order of increasing Atomic masses. He started with the element having the lowest atomic mass and ended at thorium which was the 56th element. He found that every 8th element had the properties similar to that of first. He compared this to the octane found in music. Therefore he called it “Law of Octaves”. Mendeleev’s Periodic Table: The main credit for classifying elements goes to Mendeleev. He arranged the elements on the basis of their fundamental properties, atomic masses and chemical properties. On this basis Mendeleev formulated a Periodic Law, which states that “the properties of elements are the periodic function of their Atomic Masses” Mendeleev’s Periodic table contains vertical columns called “groups” and horizontal row called “Periods”. Get Full Course To Study Offline through our website: http://www.m-learning.in Call Us at : (+91)9826023696, 9826023096 Mail us at :[email protected]