This book provides a systematic description of the molecular structures and bonding in simple compounds of the main group elements with particular emphasis on bond distances, bond energies and coordination geometries. The description includes the structures of hydrogen, halogen and methyl derivatives of the elements in each group, some of these molecules are ionic, some polar covalent. The survey of molecules whose structures conform to well-established trends is followed by representative examples of molecules that do not conform. It also describes electron donor-acceptor and hydrogen bonded complexes. Chemists use models to systematize our knowledge, to memorize information and to predict the structures of compounds that have not yet been studied. The book provides a lucid discussion of a number of models such as the Lewis electron-pair bond and the VSEPR models, the spherical and polarizable ion models, and molecular orbital calculations, and it outlines the successes and failures of each. `A light and didactic reading on the structure of molecules of main-group elements. The author has put his four decades of research experience into this book and made excellent use of some 300 representative examples. ' Magdolna Hargittai, Hungarian Academy of Sciences`No other book brings together the analysis of molecules from normal to unusual, and brings together so many different approaches. This book will contribute to increase our critical understanding of molecules, which is very important.' Odile Eisenstein, University of Montpellier This book describes the structures of molecules, i.e. their shape and size, as determined by experiments or advanced theoretical calculations, and gives an introduction to the simple concepts that chemists use to interpret these structures Professor Arne Haaland Department of Chemistry University of Oslo Senior lecturer at the University of Oslo from 1963, professor from 1986 Visiting professor at the University of Dar es Salaam (Tanzania) 1975-77 Visiting professor Oregon State University 1982-83 Visiting professor at Universität Tübingen 1992-93 Published 200 research papers on molecular structures and chemical bonding (with 6000 citations) Member of the Norwegian Academy of Science and Letters and its human rights committee