Question

Explain the periodic table given by mandellev

Answer 1

Description of Mendeleev's Periodic Table
a) In the periodic table, the elements are arranged in vertical columns called groups and horizontal rows are known as periods.

b) There are seven periods or horizontal rows in Mendeleev's periodic table. In order to accommodate more elements the periods 4, 5, 6 and 7 are divided into two halves. (As shown in above figure, the first half of the elements are placed in the upper left corners and the second half of them occupy the lower right corners in each box).

c) There are eight groups (noble gas was not introduced in Mendeleev's time which was introduced later as zero group, giving the total of nine groups) designated by the Roman numbers from I to VIII. Group VIII contains traits of elements. Later, in modified form of periodic table, each group except VIII has been divided into two sub-groups.

d) Zero-group: Mendeleev arranged only about 60 elements known at that time. After the discovery of the inert gas elements by William Ramsay and Lord Rayleigh, these were included in the zero group. Ramsay and Rayleigh were awarded Nobel prize in 1904 for their discoveries.


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