Question

How many series’ of transition elements are present in the periodic table?

(a) One

(b) Two

(c) Three

(d) Four

The question was posed to me in an international level competition.

I would like to ask this question from Position of the Periodic Table topic in section D and F-Block Elements of Chemistry – Class 12

Answer 1

Correct choice is (d) Four

Best explanation: Unlike s or p block elements which are usually discussed as columns or groups, d-block elements are better discussed by classifying them into horizontal series. In the periodic table, there are four main transition series of elements corresponding to filling of 3d, 4d, 5d and 6d sublevels in the 4^th, 5^th, 6^th and 7^th periods.