Give the structural features of modern periodic law.

Explanation

(i) According to the recommendation of IUPAC , the groups are numbered from 1 to 18 A
(ii) There are 18 vertical colounms which constitute 18 groups or families.
(iii) There are 7 horizontal rows of the periodic table know as periods .
(iv) The first period contains two elements . One present in first group and the other in 18 th group
(v) Second and third periods contain 8 elements in each . (vi) Fourth and fifth periods are completely filled as they contain 18 elements in each . (vii) The sixth period contains 32 elements . The seventh is incomplete. Fourteen elements of both sixth and seventh periods are placed in separate panels at the bottom of the table.
(viii) This periodic table is important and useful because we can predict the properties of any element using periodic trend.