FACES (katures Associated with Chemical Entities) II. Hydrocarbon lsomers and Their Graphs Russell D. Larsen Texas Tech University, Lubbock, TX 79409 In a previous paper1 we introduced the device of associating physical properties of chemical elements and compounds with face features. The basic technique was developed by the statistician, ChernofD, and improved and extended by Flury and Riedwy13, in order to display a variety of nonchemical multivariate data. We have found the technique to be a nowerful and dramatic (if not humorous). wav" to show the multiplicity of trends that are so common when considering chemical coneeners and homoloeous series of chemical compounds. In our first paper we considered and contrasted the first two rows of elements in the periodic tahle and thereby showed the possibility for a new periodic tahle containing clearly visualizable trends in addition to the usual atomic symbol, weight, and number. For example, by assigning the numerical value of the absolute entropy to the "fatness" of the face, one can immediately see which elements are gases under normal conditions of temperature and pressure-in fact, the visual differentiation is so obvious that even children can pick out the gases from the metals once they are told what to look for. In that paper, we also contrasted the 10 first-row transition metals, and-to illustrate how the technique works with compounds-we displayed the homologous series of hydrogen halides and alkali fluorides. We have recently modified the FACES program in order
to he able to display simultaneously the structural features of compounds as well as the faces themselves. In particular, to show the possibilities, we have plotted face features for the isomers of pentane and hexane. In this case, we believe it
' Larsen, R. D. J. Chem. Educ. 1986, 63, 505.
Chernoff, H. J. Amer. Stat. Assn. 1973, 68,361. Flury, B.: Riedwyl, H. J. Amer. Stat. Assn. 1981, 76, 757.
Figure 2. (right) Face feature representations for 11 physical properties of the hexane isomers.
T a b l e 1.
F a c e Feature Assignments for Pentane Isomers
Propetty No.
1 2 3 4 5
6 7
Figure 1. (ieH) Face feature representations for 11 physical properties of the pentane isomers.
8 9 10 11
Volume 63
Physical Prop.
Face Feature
Boiling Point Refractive index Density Melting paint dtldp v8scosity (absolute) abs entropy (So) H"-h0 Specific heat (%) Heat of formation
DEEB (density eyebrow) NOSE (nose size) CUM0 (curv mouth) LOHA (lower hairline) EYSi (eye size) EYSL (eye slant) VPEB (vert pos eyebrow) HPEB (hor pos eyebrow) FALl (face line) UPHl (upper hairline) HPEY (hor poe eye)
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Table 2.
Face Feature Asslgnmenlr lor Hexane Isomers
Property NO.
Physical Prop.
Face Feature
1 2 3 4 5
&oiling Point Refractive index Density Critical pressure Critical temp. Surface tension abs entrapy (S?
DEE6 (density eyebrow) NOSE (nose size) CUM0 ( G U N mouth) LOHA (ioww hairline) EYSl (eye size) EYSL (eye slant) VPEB ("art pw eyebrow) HPEB (hor eyebrow) FALI (face line) UPHl (upper hairline) HPEY (har pos eye)
6 7
8
A%
9 10
specific teat (5) Heat of formation
11
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pas
to be crucial to show the graphs of the isomers because, of course, it is the chain branching that presumably gives rise
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Journal of Chemical Education
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differences in physical prnperties which these species uossrss. The resdr of this modification of the FACES DrO;ram is s h o w in Figures 1 and 2. T h r isomorphism beliven physical propertiesand facr teatures iscontained inl'ahles I and 2. ~ o t that, e whereas earlier1 we associated the eyebrow density with the atomic weight or with the molecular weight depending on the circumst&e, given that all isomers of a specific variety have the same molecular weight, we now have assigned the eyebrow density to the boiling point of an isomer because the boiling point is an important isomeric property and also because the eyebrow density is one the most easily recognizable face features. A t present, the FACES program is not available on a microcomputer; currently, the program is running on a mainframe, but i t is able to be previewed and edited on an Apple Macintosh configured as a graphics terminal using Tekalike. FACES plotfiles can be converted to MacPaint files and thereby modified as desired.
