Question

Besides gallium, which other elements have since been discovered that were left by Mendeleev in his Periodic Table? (Any two)

Answer 1

Mendeleev’s periodic law — The properties of elements are a periodic function of their atomic masses

• It means when we arrange the elements in increasing order of their atomic masses then after some times elements are produced similar properties
• The elements having similar chemical properties form oxides and hydrides having similar formulae.
• Mendeleev used these properties for creating his periodic table
• It was the discovery of atomic number which led to a change in Mendeleev’s periodic law which was based on atomic mass

Limitations of Mendeleev’s classification of elements

• Limitations of Mendeleev’s classification of elements:
• Failed to explain the position of isotopes.
• The wrong order of atomic masses of some elements could not be explained.
• A position for hydrogen could not be assigned in the periodic table

Besides gallium Germanium and Scandium is the element that are left by Mendeleev in his Periodic Table since its discovery.