Question

Differentiate between the arrangement of elements by Mendeleev periodic table and modern periodic table..?

Answer 1

Mendeleev's periodic table:

1.. Elements are arranged in the increasing order of their atomic masses .
2..There are a total of 7 groups ( columns) and 6 periods( rows).
3.. Elements having similar properties were placed directly under one another.
4..The position of hydrogen could not be explained.
5..No distinguishing positions for metals and non metal.



Modern periodic table:


1..Elements are arranged in the increasing order of their atomic numbers.
2..There are a total 18 groups ( columns) and 7 periods ( row).
3.. Elements having the same valance shell are present in the same period while elements having the same number of valance electrons are present in the same group.
4..Hydrogen is placed above alkali metals.
5..Metals are present at the left hand side whereas non metals are present at the right hand side of the periodic table.