Question

Mendelleves advantage and drawback

Answer 1

mandaleev sugested the 3 elements before their discovery that Eka silicon for scandium
Eka boron for barallium and Eka alluminum for germannium and disadvantages are that he couldn't explained the position of hydrogen and the positions of isotopes

Answer 2

Answer...

☆☆ MENDELEEV'S PERIODIC LAW ☆☆

¤¤ By Evonvich Mendeleev in 1872. According to his law, " The physical and chemical properties of elements are periodic functions of their atomic masses".

¤¤ He gave 9 veritcal columns called groups.

¤¤ He gave 7 horizontal columns called periods.

☆☆ ADVANTAGES OF MENDELEEV'S PERIODIC LAW ☆☆

¤¤ He gave simplified and systematic way for study of elements.

¤¤ He left space for the elements which were not discovered at that time and gave night prediction.

¤¤ He gave correction in atomic weights of some elements. E.g. Be was 13.5 and was corrected to "9".

☆☆ DRAWBACKS OF MENDELEEV'S PERIODIC LAW

¤¤ He could not identify position of hydrogen exactly.

¤¤ The arrangement according to atomic weight was not correct.

¤¤ No space for Isotopes.

¤¤ Lanthanoids and Actinoids were not given proper position.

¤¤ Dissimilar elements grouped together. E.g. Li, Na, K with Cu, Ag and Au.