Speaker

Roald Hoffmann

Chemistry and Chemical Biology, Cornell University

Date＆Time

2022.04.14（Thur）AM 8:00

Location

Zoom Meeting ID：950 680 6742 Password：402533

https://m.koushare.com/lives/room/596793

Reporter

Roald Hoffmann studied chemistry at Columbia and Harvard Universities (Ph.D. 1962). Since 1965 he is at Cornell University, now as the Frank H. T. Rhodes Professor of Humane Letters. His interests revolve around theoretical chemistry; the electronic structure of organic, inorganic and organometallic molecules, also of one-, two-, and three-dimensional extended structure; and geometrics and reactivity of molecules. He has received many of the honors of his profession, including the 1981 Nobel Prize in Chemistry (shared with Kenichi Fukui). He is a member of the American Academy of Arts and Sciences, the National Academy of Sciences of USA, et al.

At Cornell, Prof. Hoffmann taught introductory chemistry half of his time. Notable also is his reaching out to the general public; he was the presenter, for example, of a television course in chemistry titled "The World of Chemistry," shown widely since 1990. As a writer, Hoffmann has carved out a land between science, poetry, and philosophy, through many essays, five non-fiction books, three plays and seven published collections of poetry, including bilingual Spanish-English and Russian-English editions published in Madrid and Moscow.

Abstract

100 million compounds, one million of which have had their structures determined, is not a bad beginning from which to form a picture of stability and bonding. I will begin a discussion of stability and reactivity, thermodynamic and kinetic, in the structures that are emerging at elevated pressures from that experience.

A second story tries to tease out ways to think about high pressure structures and stoichiometries of alkali metal and alkaline earth halides and hydrides, based mainly on calculations by the Zurek group. This story leads back and forth between elevated and ambient pressure realms, touching on materials as diverse as trihalides, polyhalides, and Arndt Simon’s alkali metal suboxides, such as Rb9O2, Cs11O3.

Basically, the effect of high pressure is to enforce proximity of atoms. Which means making more “bonds” with the same number of electrons. How to think about that?