What are the important topics in chapter of periodic classification of

1.	What are the important topics in chapter of periodic classification of elements????
Answer» Drawback and adcantages of all scientists.........modern periodic table of 20 to 25 elements..........both .laws. 1. difference between modern and Mendellev periodic table.2. difference between the properties of periods and groups. 3. Dobereiner\'s traids and it\'s limitations. 4. Law of octavates and limitations. 5. Trends in the modern periodic table - Valency, atomic size , metallic character.

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