Mandleev

• Mendeleev’s Periodic Table:

1. Mendeleev believed  that  the  atomic  mass  of  an  element  was  the  most  fundamental  property  in classifying elements.
2. Mendeleev  arranged  elements  in  the  increasing  order  of  their  atomic  masses  and  observed  that  the elements showed repetition after certain intervals in their physical and chemical properties.
3. He arranged the known elements in the increasing order of their atomic masses in horizontal rows, till he encountered an element which had properties similar to the first element.
4. Mendeleev placed the element below the first element and started the second row of elements.
5. Proceeding in this way, he created the first periodic table containing 63 elements, arranged according to their properties.

Mendeleev’s Periodic Law: The physical and chemical properties of elements are a periodic function of their atomic masses.

Features of Mendeleev’s Periodic Table:

1. There  are  seven  horizontal  rows  in  the  periodic  table,  numbered  from 1  to  7.  These seven rows are called periods.
2. There  are  eight  vertical  columns  numbered  from  I  to  VIII.  These eight columns are called groups. Groups I to VII are further divided into sub groups A and B.
3. The properties of elements in a particular period show regular gradation from left to right.