MNEMONIC DEVICES in CHEMISTRY JOHN BERMINGHAM, LIEUTENANT, U. S. N. United States Naval Academy, Annapolis, ,&rgland
This paper deals with the w e of key-sentences and keywords as a n aid to the memory i n cases where the facts are not rationally deducible and tends to show that the key-word i s a valuable aid for this purpose.
+ + + + + + ARK TWAIN advised history students who had difficulty in remembering dates to conjure up a picture in the imagination in such a way as to associate the date with the picture. No matter how bizarre or improbable the imagined picture was, as long as the student had done i t for himself the picture would help to fix the date indelibly in his mind. That such a device has some merits for the student of history who suffers as the result of a poor memory will be conceded when it is realized that in the study of history the principal aim is not to gather a store of miscellaneous facts but to enable the student to draw conclusions from the facts. For this purpose ability to connect facts with dates is of considerable value. The story of the teacher of elementary history who employed a key-sentence to fix a date in the minds of the students is no doubt familiar. The sentence was a jingle "In 1492 Columbus sailed the ocean blue." For causes unknown and much to the distress of the teacher the jingle became in a short time "In 1493 Columbus sailed the deep blue sea!" Familiar also is the key-sentence used by music students to give the order of literation of the staff in music, "Every good boy does fairly" and tbe key-word which accompanied it "f-a-c-e" representing the spaces. Key-sentences are occasionally successful as a mnemonic device but require considerable composi-
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tional skill usually and a well-developed sense of humor. At the Naval Academy for many years a keysentence, outlining, by means of the 6rst letter of each word, the process for the manufacture of smokeless powder was used and passed from class to class. In fact, midshipmen of the fourth class learned the sentence before they knew it had any special meaning other than its mention of a professor long revered for his connection with Naval Academy football. The sentence was "Paul Dashiell bet six dam bits; six dam bits did Paul Dashiell bet." "Skinny Paul" has since passed to his reward, but his name will long be remembered and not a little through this key-sentence, for however the process of manufacturing smokeless powder be modernized it is likely that the initial stages will continue to be pulping and drowning and that (8 p I , i rd in the key-sentence will always be represented by "Paul Dashiell." Student lore generally, the world over, is replete with examples such as "Queen Victoria leered at King Albert" and "Victor wants the waterpistol to shoot Papa," each with a particular appeal to undergraduate interest and sense of humor. They achieve a kind of immortality and curiously enough do carry with them the academic tid-bit they were devised to recall. However, wit and humor are not always Auid when the mind is seriously a t work in chemistry, and without the humorous inflection the key-sentence is likely to be little improvement over the arrangement of facts in bulk. The scientist, particularly the chemist, is greatly dependent on his memory. The student in chemistry soon finds that his progress depends largely on his ability to recall that which his mind has succeeded in 9,
assimilating. A vicious circle is likely to develop if difficulty in recollection impedes subsequent assimilation. Of a class of seven hundred fifty-three young gentlemen entering the Naval Academy in June, 1938 thirtyfive per cent. had had a t least one year of college chemistry, plus, in most cases, one year of high-school chemistry. Forty-three per cent. had had one year of high-school chemistry. The remaining twenty-two per cent. had had no previous chemistry. Most of these latter and some few of the "previous chemistry" categories find chemistry a trying subject. Those worst situated are those who do not assimilate readily in study, recitation, and laboratory. For them the only hope is to be able to cultivate the art within the allotted time, the first semester or term. For those with faulty recalling powers the standard pedagogical recourse is "overlearning," that is, to extend the process of study beyond ordinary acceptance as understood to the point where the material is not only understood but can be reproduced. The mortality of material subjected to this treatment is great, particularly in the press of the scholastic year, and in many academic schedules "overlearning" time is not available. The Naval Academy schedule is an acute example, and partly on this ground recommendations have been made to extend the course to six years. A device which requires no particular skill and which is often successful in aiding the student to commit to memory such material as the electrochemical series, valence numbers, and other facts not rationally deducible is the key-word. The key-word is a word fabricated from letters or syllables or both which are taken from the material it is desired to commit to memory. This is done in such a way that each letter or syllable represents a fact. The key-word is pronounceable and the spelling is phonetic. These are important features, as the memory functions most efficiently on the sound of the word which, h'eing spelled phonetically, can be then reproduced. For example the electrochemical series can be represented by the following key-words, PoSCa MagAl ManZiCh INTL CuBiAMS. The common valence numbers can he embodied in something like the following.
Uniualent HyNaKAgCuClBrI NONHOH Bivalent CaBaMagZiFeCuSOHg SOCO Triwalent AlAs FeNSbBiP PO All the valence numbers of the elements included in the key-word are not given, and carbon is omitted. Radical subscripts are omitted as they are readily recalled by the radical itself. For elements having valence numbers of four and higher additional key-words may be devised. The above is merely an example. It will be noted that there is a strong similarity between the use of the above key-words and the use of the Periodic Table. Note that where necessary to make the words pronounceable and to keep the spellingphonetic, departures have been made from the standard chemical abbreviations. The key-word system can be extended to other groupings and summaries of facts which from their nature depend on brute force memory work to recall them. The summary headed "Kinetic Theory of Gases" is thus represented by taking a significant syllablc from each statmwnt of the summary and cum11ini11c them into a word snch as hIulColSrt.%ttrRE. While many educators will scorn such a practice as even the above limited uses of key-words it must be borne in mind that a strong memory is not necessarily an indication of mental development. The key-word is not a habit-forming device, nor does it lead to undesirable practices. It is a kind of mental shorthand approximating in its employment that of the Periodic Table which many students become able to visualize mentally in whole or in part for the purpose of obtaining information therefrom. It gives the harried student a grip on the ladder when the going is heavy and for this reason may be profitably suggested. The limitations in the use of key-words may be summed up as follows.
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(1) It is to be used only with facts not rationally deducible. (2) The student must compose his own key-word if i t is to be remembered. (3) The key-word must be pronounceable and spelled phonetically.
