DEPARTMENT OF CHEMISTRY A. N. COLLEGE, PATNA GRADE ‘A’ Re-accredited by NAAC C.P.E. STATUS BY U.G.C

Report Lecture on ‘A New Look To Periodic Table’ (September 14, 2017) By Prof H C Rai University Professor (Retd), Department of Chemistry, BRAB University, Muzaffarpur

As science advances, its laws become fewer but of greater scope. In this respect the Periodic Law, which is the basis of the Periodic Table, represents a major step in the progress of chemistry — it affords the natural classification of the elements. The Periodic Table was developed by chemists more than one hundred years ago as a correlation for the properties of the elements. With the discovery of the internal structure of the atom, it became recognized by physicists as a natural law. When the crystalline structure of solids was studied, the nature of the chemical bonds was understood, and the theory of metals was put forward, it became an essential tool not only for chemists and physicists, but for metallurgists as well. From Mendeleev's original periodic table, elements have been basically arranged by valence (groups in columns) and the repetition therein (periods in rows). Over the years and with discoveries in atomic structure, this schema has been adjusted and expanded, but not changed as a principle. The oldest periodic table is the short form table (columns I–VIII) by Dmitri Mendeleev, which shows secondary chemical kinships. H. G. Deming used the so-called long periodic table (18 columns) which appeared in the USA for the first time in 1923 (Wiley), and was the first to designate the first two and the last five main groups with the notation "A", and the intervening transition groups with the notation "B". The numeration was chosen so that the characteristic oxides of the B groups would correspond to those of the A groups. The iron, cobalt, and nickel groups were designated neither A nor B. The noble-gas group was originally attached (by Deming) to the left side of the periodic table. The group was later switched to the right side and usually labeled as group VIIIA. In the extended periodic table, suggested by Glenn T. Seaborg in 1969, yet unknown elements are included up to atomic number 218. Theoretical periods above regular period 7 are added. In the research field of superatoms, clusters of atoms have properties of single atoms of another element. It is suggested to extend the periodic table with a second layer to be occupied with these cluster compounds. The latest addition to this multi-story table is the aluminium cluster ion, which behaves like a multivalent germanium atom. Chemists should abandon numbering the groups in the Periodic Table, and to give the following descriptive names instead: • Monatomic nonmetals • Covalent nonmetals • Metalloids • Typical metals • Less typical metals • Transition metals with vertical similarity • Transition metals with horizontal similarity (iron, cobalt, nickel) • Transition metals with vertical and horizontal similarity (platinum group metals) • Inner transition metals: The lanthanides The actinides An advantage of this classification would be putting each member of a group in its logical position.

Dr Anju Gupta, Dr Tripti Gangwar, Dr Anil Kumar, Dr Subhash Pd Singh and Dr Brameshwar and supporting staff of the Department extended full support to the workshop. The Principal of the college Dr Shashi Pratap Shahi appreciated the Chemistry Departmentt for organizing such an informative and useful lecture for the benefit of teachers and students. Students of MSc Semester-I & III in general enjoyed the lecture.

- Faculty Members Department of Chemistry, A N College, Patna-13