April 19, 2004
On the inadequacy of some historical chemical terminology
I was helping one of my chemistry classmates study after class this morning. Our topic of conversation was electrochemistry. My classmate's confusion was over the terminology used in voltaic cells, e.g. oxidation, reduction, cathode, anode, cation, anion, etc. It occurred to me in the course of discussion that her confusion was due to the use of the term "reduction", which simply means "a reduction in oxidation state by electron donation"; it's a useful numerical indication of that state, not of the physical configuration of the element being "reduced". I'd long ago internalized the actual meaning, so it had slipped me that to a very bright but non-native speaker of English, "reduction" would seem to indicate a physical reduction of some dimension of the affected chemical species!
I had one of those "aha" moments and drew her a diagram of what actually happens with an example species being reduced, in this case a bare proton (a hydrogen ion, H+): H+ has an oxidation state of +1, which can be reduced by an electron donor to 0. The atomic diameter of the ion is as small as a species can get, effectively equal to the proton's diameter; the addition of an electron ("reduction") drastically increases, in a relative sense, the effective atomic diameter of the neutral hydrogen (disregarding the issue of likelihood of a monatomic non-ionic hydrogen), which is "a bigger dimension", not "a reduced dimension".
Chemistry - and most of science - is full of such interesting and sometimes annoying little ambiguities which are the legacy of discovery and provisional definition. Don't even get me started on all the different symbols used to denote "energy"...
Posted by Russell Whitaker at April 19, 2004 12:40 PM | TrackBack