Question

5. Mention three significant features of Mendeleev’s Periodic table

Answer 1

Answer:

Elements arranged in increased atomic mass

there are seven periods and eight columns

each columns of first seven are subdivided into A and B subgroups.

Answer 2

Answer:

(1) Mendeleev arranged the elements (known at that time) in an increasing order of their atomic masses.

(2) The serial or ordinal number of an element in this order was referred to as atomic number.

(3) The periodic table has vertical columns called groups and horizontal raws (now called as periods.)

(4) Properties in a period showed gradual change from left to right, whereas the elements with similar properties were arranged in the same group

(5) He left some gaps corresponding to certain atomic numbers in the periodic table to maintain periodicity of the properties, Newly discovered elements fitted into the gaps with their properties as predicted by the Mendeleev's periodic law.

(6) Inert gases, discovered in later years could be accomodated in this periodic table by creating an additional group.