The placement of elements in Mendeleeff’s periodic table helped in correcting the atomic masses of some elements like, beryllium, indium and gold.
    For example, At the time of Mendeleeff, beryllium (Be) was given atomic weight 13.5.
        Atomic weight = equivalent weight × valency The equivalent weight of Be was found experimentally as 4.5 and its valency was thought as 3. Therefore, the atomic weight of beryllium was given as 4.5 × 3 = 13.5. With this atomic weight it had to be placed in a wrong group in the table. He said that its valency should be only 2. Then its atomic weight would be 4.5 × 2 = 9. If atomic weight of ‘Be’ is 9 it would be fit in the second group and its properties practically are similar to Mg, Ca etc., of the second group elements. He also helped in the calculation of the correct atomic weights of ‘Indium’ and ‘Gold’ in this manner.

Some anomalous series of elements like ‘Te’ and ‘I’ were observed in the table. The anomalous series contained elements with more atomic weights like ‘Te’ (127.6 U) placed before the elements with less atomic weights like ‘I’ (126.9 U). Mendeleeff accepted minor inversions in the order of increasing atomic weights as these inversions resulted in elements being placed in the correct groups.
    It was the extraordinary thinking of Mendeleeff that made the chemists to accept the periodic table and recognise Mendeleeff more than anyone else as the originator of the periodic law.