State Mendeleev's period law.

Explanation

(i) The Russian scientist Dmitri Mendeleev developed the periodic table of elements during the period 1869 to 1872 A.D.
(ii) Mendeleev.s periodic table is the most important step in the classification of elements.
(iii) Mendeleev considered the fundamental property of elements, namely the atomic mass as standard and arranged 63 elements known at that time in an increasing order of their atomic masses.
(iv) Then, he transferred this into the periodic table of elements in accordance with the physical and chemical properties of these elements.
(v) He organized the periodic table on the basis of the chemical and physical properties of the elements.
(vi) These were the molecular formulae of hydrides and oxides of the elements, melting points, boiling points and densities of the elements and their hydrides and oxides.
(vii) Mendeleev found that the elements with similar physical and chemical properties repeat after a definite interval.
(viii) On the basis of this finding, Mendeleev, stated the following periodic law "Properties of elements are periodic function of their atomic masses".