(i) Why do we classify elements?

(ii) What are the two criteria used in the development of Modern Periodic Table?




We classify the elements so as to ensure a systematic and simplified study . By classification, we can study the properties of elements and their compounds properly.


In the modern periodic table, elements were classified based on their 

  • atomic number 
  • chemical properties


Position of Metals Non-Metals and Metalloids in The Periodic Table - Teachoo.jpg

Metals are placed towards the left of the periodic table, non metals towards the right and metalloids are present in the middle in a zigzag fashion.


In the modern periodic table, elements are classified based on their atomic number and not atomic masses .  

Although isotopes have different atomic masses, they have the same atomic number and similar chemical properties. 

So, they should be placed in the same slot .

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CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo