J. lnorg. Nuel. Chem., 1965, Vol. 27, p. 2685. Pergamon Press Ltd. Printed in Northern Ireland
B. J. AYLETTand B. C. SMITH." Problems in Inorganic Chemistry. English Universities Press Ltd. (1965). 154 + xii pp. 21s. THERE are two principal objections to a collection of questions and answers in Inorganic Chemistry. Firstly it reads like a set of examination papers and secondly the answers are greatly oversimplified. The authors overcome the first objection by choosing the questions with considerable skill, frequently giving a brief introduction where appropriate. Certainly the choice of questions reflects modern interests in the subject, and it is good to see so much space given to thermodynamics. The second point does not apply to the numerical problems and the simple factual questions but the authors are, not surprisingly, less successful at trying to explain difficult and fundamental points in two lines. This is only partly met by supplying large numbers of references; it would have been better to give the references alone. Two examples will illustrate this point. In chapter 3, Q. 4, we are asked how the structures of some boron hydrides are explained in terms of three-centre bonds and the answer suggests that the "lowest hydrides are described conveniently by a three-centre bond approach. This is less satisfactory for pentaborane-9 and molecular-orbital descriptions are required for the higher hydrides," implying that a three-centre bond cannot be described by an m.o. treatment. In chapter 1, Q. 34, we are asked to give the probable states of hybridization in the xenon fluorides; in view of the controversy about the bonding in these compounds it is rather unhelpful to state simply spSd for XeF2 and spSd2 for XeF4. Thus this little book, which seems remarkably free of errors, is likely to prove very useful to those undergraduates who want practice at numerical problems and factual queries but he should be warned about the more fundamental questions and encouraged to follow up the references the authors give.
J. J. TURNER