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what were the criterion used by mendeev in creating his periodic table/??

Mendeleeff arranged elements in increasing order of atomic weights in the form of a table called the 'periodic table'

-This arrangement had elements with similar properties appearing at regular intervals .
-This phenomenon is called 'periodicity of properties (the properties which repeat themselves at regular intervals are called 'periodic properties' which include atomic radius, ionisation potential .electron affinity etc ). 

Mendeleeff's arrangement of periodic table 
Elements were arranged in increasing order of atomic weights in horizontal rows called periods and vertical columns called groups .
Elements which are similar with respect to their chemical properties are grouped together and have the atomic weights of nearly the same value .
Elements in the same group had the same valency and similar chemical properties .
Based on the periodicity of properties a number of gaps were left in the table -for undiscovered elements that is elements now discovered example scandium ,gallium originally called eke- boron, eka-aluminium ,eka-silicon respectively 
-The properties of the undiscovered elements left in the vacant gaps was predicted .
-Incorrect atomic weights of some of the arranged elements -were corrected with the knowledge of the atomic weights of the adjacent elements .


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