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 Mendeleev’s classification of elements:
Periodic Law:

The physical and chemical properties of elements are the periodic
function of their atomic masses.i.e Elements are arranged in increasing

order of their atomic masses.
Explanation of Mendeleev’s table:

 There were 8 vertical columns known as groups and 7 horizontal rows
known as periods.

 Groups from I to VII are meant for normal elements and group VIII is for
transition elements.

 Elements having similar properties have been kept in the same group.
For example; Li, K, Rb, etc are in first group.

 There were 63 elements in Mendeleev’s periodic table.
Advantages of Mendeleev’s table:
(a) Prediction of new elements.

(b) Correction of atomic masses.

(Atomic mass of ‘Be’ was corrected
From 13.5 to 9)
Disadvantages Mendeleev’s table:

(a)No proper position of Hydrogen
Was given.

(b)The space for one element is occupied by three elements.
(Triads-Fe, Co, Ni)

(c)It was silent about the position ofisotopes.
(d)Position of Lanthanoids & Actinoids was not properly assigned.

(e)Dissimilar elements were placedtogether.(Alkali metals & coinage Metals)