Question

Explain the three merits of mendeleev's periodic table

Answer 1

Achievement of Mendeleev 's periodic table : 1. It was easy to study the physical and chemical properties of various elements. 2.Mendeleev's left some gaps in his periodic table. He predicted the existence of some elements that had not been discovered at that time. His prediction were quite true as elements such as scandium, gallium and germanium were discovered later. 3.The gases such helium, neon and argon, which were discovered later, were placed in a new group without disturbing the existing elements.

Answer 2

Explanation:

Mendeleev's Periodic table .

→ When Mendeleev started his work , 63 elements were known at that time .

→ He examined the relationship between the atomic masses of the elements and their physical and chemical properties .

→  Mendeleev concentrated on the compounds formed by elements with oxygen and hydrogen .

Classification criteria :-

1. The formulae of the hydrides and oxides formed by an element were treated as one of the basic properties of an element foe its classification.

2. He then took 63 cards and on each cards he wrote down the properties of one element. He sorted out the elements with similar properties and pinned the cards todether on the wall .He observed that most of the elements got a place in the periodic table and were arranged in the order of increasing atomic masses .

On this basis , Mendeleev formulated a periodic law .

→ Which states that " The properties of elements are the periodic function of their atomic masses .