Question

Achievement of Mendeleev periodic table
4 points ​

Answer 1

1. Mendeleev's periodic table has horizontal rows called periods and vertical columns called groups.

2. All elements of a particular group show similar properties as they have the same valencies.

3. Mendeleev left spaces for the undiscovered elements like Gallium, Germanium, etc.

4. Mendeleev was able to correct certain incorrect atomic weights.

Answer 2

▪ Although he relied on increasing order of atomic mass, he gave the preference to put elements with similar properties in a group. He used the similarities in oxides and hydrides formula formed by the elements.

▪ He left gaps for elements to be discovered and predicted it's properties.

▪ Corrected some atomic measurements so that thise elements could fit in to periodic table.

▪ He slightly twisted the increasing order of atomic masses so that he could keep the similar elements in same group. So, in case, he gave importance to similarities in chemical properties which lead to modern periodic law.

▪ He was the first to propose 'Mendeleev periodic law'.