How would you justify the presence of 18 elements in the period of th

1.	How would you justify the presence of 18 elements in the period of the periodic table.
Answer» PRD, there are 2 s block ELEMENTS and 6 p block as in 2nd & 3RD period. But from 4th period there is an increase in elements of 10 due to the presence of d block. In 4th & 5th there are 10 d block elements alongwith 2 s and 6 p. So, here are 18 elements.

Discussion