The Periodic Table is arguably the most important concept in chemistry, both in principle and in practice….An awareness of the Periodic Table is essential to anyone who wishes to disentangle the world and see how it is built up from the fundamental building blocks of the chemistry, the chemical elements.”
The chapter on ‘Classification in Elements and Periodicity in Properties’ in NCERT’s Class 11 Chemistry textbook begins with these words of American chemist Glenn T Seaborg. Yet, a full chapter, which introduces students to the topic, has been removed from NCERT’s Class 10 Science textbook as part of the council’s “rationalisation” exercise. The Class 11 chapter on the topic, however, remains part of the syllabus.