Arnold J. Gordon Catholic University of Americo
Washington, D. C. 20017
A Survey of Atomic and Molecular Models
Scale models of atoms, orbitals, crystals, and molecules have become increasingly popular for use in teaching and research, especially in connection with stereochemical problems. Although models have definite shortcomings and limitations (la) they can be very useful and are often indispensable. There are many types of model sets commercially available; this article describes all those known to the author and provides names and addresses of suppliers. Only models in use in the U. S. are surveyed. No attempt has been made to provide an exhaustive list of suppliers (some models are available from only one supplier). Only one representative address is given for the major supply houses. I n addition to commercial sets, there are many homemade model systems described in the literature (including a recent book by Bassow, ( I b ) ) . Some recent systems are found in (2-11); a descriptive title a n t construction material are given with each reference.
Crystal Lattice Models Type Crystal Plane Model Clystd Systems
Crystal Lattices
Description Heavy coated cardboard on metd frame; illustrates geometry of crystal faces and Miller indices. Many types including preassembled or kit form; ball-andstick; etc. made of plastic, foam, wood andlor metd. Illustrate the six basic crystal forms. Preassembled or in kit form (ball-and-spoke; foam; ete.) these demonstrate specific crystal structures (e.g., NaCI, graphite, wurtzite, etc.); some are space filling (supplier 4 ) .
Supplier 4
4, 5, 7, 10,ll
4, 5, 7, 10, 11
Atom and Orbital Models
Molecular Model Sets
These are used to demonstrate details of isolated atoms and atomic or hybrid orbitals. Discussions of atomic and molecular orbitals that are helpful in connection with the use of such models are found in (12~).
Many of the types described in the table are available as different complete sets (such as general chemistry, organic chemistry, et al.) and as separate elements; price and descriptive details are available from the supplier or in current catalogs. The characteristics of each type are indicated in the table by a key, defined as follows
Type Alom
Construction Ni-plated metal
Atom
Plastic coated cardboard
Orbit,nl Orbital
Plastic template "Sturdy"
Orbital
Drilled balls; metal frame
Atom, orbital
Suppliers Description Bob-Sommerfeld model; 4 user magnets; 15 in. tall 4 Fold out type showing elementary part,icles (TI-Ne) 4 For drawing AO's, MO's For making models of all 4 s, p, and d atomic, hybrid, and molecular orbitals with snap fasteners; 8 in. t,all Demonstrate angular dis10 t r i b u h n of all s, p, d, and f orbitals; about 10 in. tall. For description, see reference (Idb). Prefolded strips; illus 5. 6 trate hybridized w b i b als on metal stands. About 7 in. on an edge.
Polyhedra Models
A variety of regular
irregular polyhedra, and shapes are available in solid or transparent ~lastic,wood, and other materials; kite for construetion of such shapes are also available (suppliers 4 and 5, among others). 30 / Journal of Chemical Education
space filling (i.e., component atoms occupy a volome to represent magnitude of relative size (electronic density)) r = bond lengths of different bonds to scale; followed in pasentheses by scale used in cm/A. a = bond angles to male v = covalent and/or Van der Wsals radii to scale m = metal pf = firm plastic or rubber pc = compressible or flexible plastic or rubber t = special tool or aid used for model assembly and/or disassembly s
=
Unless mentioned otherwise: all atoms are attached by snap-on connectors of some type; most, if not all the usual atoms are available in most of their oxidation (coordination) states (H, C, N, 0, halogens, P, S, metals); atoms are color coded. References to the literature describing special p e s of some models are given for each type.'
1 A "visual motion device" might be mentioned here; although this battery-operated item is not strictly classified with models, the E. M. E. Molecular Motion Demonstrator is used to simulate atomic and molecular motion to classroom-size groups (Educational Materials and Eqoipment Co., Box 63, Bronxville, N. Y. 10708). A similar device, 'The Molecular Dynamics Sirnulalor" is available from Holt, Rinehart and Winston, Inc., 383 Madison Ave., New York, 10017.
Commercially Available Molecular Model Sets
TYP@ Corey-Pauling-Koltun (CPK) (13) Courtauld (14) Dreiding (16) Fieser Stereomodels (18)
Fisher-HirschfelderTaylor (FHT) (17) Framework Molecular Models (FMM) (18) Frey Fused Molecule Sets Godfrey-Bronwill a ) Molecular Models b) Stereomodels (10)
HGS (BenjaminMaruaen) Kendrew Lande-Edmund ($0) Leybold (Stuart-Briedeb) SRP
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Ckaracte~i8tdc8 s,r(l.25),s,v,pf,t
Comrnent.9 Designed for bio molecules (RNA, DNA, etc.); many sets, including one for steroids, available. Has distortable links (for strained bonds, etc.); good for stereochemical problems. Connection by tubes and rods, very easy to use, provides uncluttered, accurate view of dimensions of molecular skeleton. Design based on Dreiding models, but made of Lexan, polyethylene, and aluminum. Inexpensive, good for student use, limited vwiety of functional groups and structural types. Only C, N, and 0 atoms color coded. Stuart-type; accurate stereomodels of large variety. Also comes as a metal-coordination model kit. Not useful for highly strained angles. Sturdy; very versatile (very similar to Leybold models s e e below). Each element a metal-pronged cluster to which color coded plastic tubing (cut to desired size) is attached; r and d orbital frames can be constructed. Very adaptable; inexpensive. Good for student use. Large, lightweight; balls coded in six colors, not to atomic scale; collars represent multiple bonds; boiud lengths not strictly to scale.
Made of pliable PVC; magnets to illustrate H-bonding. Versatile. For visualizing skeletal structure and dimensions; limited no. of functional groups. Tetrahedra made by snapping slotted "halfatoms" togefher. Made of various polyhedra (ABS resin) with holes for straight and eumed tubing; sturdy, versatile, inexpensive. Only C-C and C H bonds to scale. Good far student use. Makes skeletal models of brass rods joined by small barrel with screws; many angles (gauge available) and lengths possible. For accurate dimension measurement. White polystyrene-rubber plastic connected by steel pins or sockets. Designed for bio-macromolecules. Series of pregrouped clusters. Not color coded. Accurate stereomodels of large variety. Not suitable for highly strained angles. Sturdy; very versatile. Similar to ball-and-stick type, but atomic units snap together directly; bond sticks and fasteners also included. Limited variety of units.
Miscellaneous
Balland-slick. Many types; most have drilled wooden balls lor atoms, wooden sticks and spring8 for bonds. Among the least expensive, but least accurate and versatile models. One supplier (5) offers polystyrene and styrofoam with threaded metal dowels as connectors. Suppliers: 3, 5, 6, 9. Kennard-Dord Stereo-Model Construetia Set. A sophisticated and elaborate set of tools and materials (plastic, metal; brazing alloy, etc.) for construction of accurate, custom-made models. Supplier: 16. Suppliers
1. Ace Scientific Supply Company, 1420 E. Linden Ave.' Linden. N. J. 07036. 2. Arthur H. Thomas Co., Vine St. a t Third, P. 0. Box 779, Philadelphia, Pa. 19105. 3. Curtin Scientific Apparatus and Chemicals, 12340 Parklawn Drive, RockviUe, Md. 20852. 4. Science Related Materials, Inc., P. 0. Box 1009, Evanston, Illinois 60204. 5. Edmund Scientific Co., 400 Edscorp Building, Barrington, N. J. @3007. 6. E. H. Sargent and Co., 4647 West Foster Avenue, Chicago, Illinois 60630. 7. E. Leybold's Nachfolger, Khln-Bayental, Germany. 8. Fisher Scientific Company, 52 Fadem Rd., Springfield, N. J. ~
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SuppliPr 16
n7M1 " u . .
9. Frey Scientific Co., 465 S. Diamond St., Msnsfield, Ohio
10. Klinger Scientific Apparatus Corp., 83-45 Parsons Blvd., Jamaica, N. Y. 11432. 11. Lapine Scientific Co., 6001 South Knox Ave., Chicago, Illinois 60629. 12. Matheson Scientific, 5922 Triumph St., Los Angeles, Calif. 90022. 13. PrenticaHall, Inc., Englewood Cliffs, N. J . 07632. 14. Rinco Instrument Co., 503 S. Pmirie St., P. 0.Box 167, Greenviile, Illinois 62246. 15. Scientific Glass Apparatus Co., 735 Broad St., Bloomfield, N .T nmnn 16. The Ealing Corporation, 2225 Massachusetts Ave., Cambridge, Mass. 02140. 17. W. A. Benjamin, Inc.. 2 Park Avenue, New York, N. Y. 10016. 18. W. Biichi Scientific Apparatus, Flawil, Switzerland. 19. Will Scientific, Inc.. Box 1050, Rochester, N. Y. 14603.
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(1) (a) For example, see MISLOW,K., "Introduction to Stereochemistry," W. A. Benjamin, Inc., 1965, pp. 42-46. (b) B ~ s s o w H., , "Construction and Uses of Atomic and Molecular Models," Pergamon Press, New York, 1968. (2) CONRAD, C., AND BENT,H., "A Jig for Making Styrofoam Moleoular Models." J . CHEM.EDUC..46. 482 (19691. (3) GYMER, R. G., "~luid-FIOW ~imulLtion of Molecular Orbitals," J. CHEM. E ~ n c . ,46, 493 (1969). (4) NYE, M. J., "Wooden Models of Asymmetric Structures,"
44903. Volume 47, Number 1 , January 1970
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(5) CRAIG,N. C., "Molecular Symmetry Models," (Lucite and brass), J . CAEM.EDUC.,46, 23 (1969). (6) RODRIGUEZ, F., "Simple Models far Polymer Stereochemistry," (use of plastic sheeting), J. CAEM.EDUC.,45. 507 flQfirtl \."--,. (7) YAMANA, S., "An Easily Constructed Tetrahedral Model," (paper), J . CAEM.EDUC.,45, 245 (1968). (8) OLSEN,R. C., "Crystal Models," (cork balls and Plexiglas), J. CAEM.EDUC.,44, 729 (1967). 19) W. J . . "The Construction of Solid Tetrahedral , , SREPPARD. and ~ctahedraiModels," (cardboard sheets), J. CHEM. EDUC.,44, 683 (1967). (10) LAESON, G. O., "Atomic and Molecular Models Made from Vinyl Covered Wire," J. &EM. EDUC.,41, 219 (1964). (11) BRUMLIK,G., "Molecular Models Featuring Molecular Orbit~als," (Adiprene L100, a flexible plastic; scale 1.3 cm/A), J. CAEM.Enuc., 38, 502 (1961). T.. "AtomicOrbitals Limits, 112) ial COHEN. , I.., AND BU~TARD. tions, and Variations," J . &EM. Enuc., 43, 187 (1966); BERRY,R. S., "Atomic Orbitals," J. CAEM.EDUC.,43, 283 (1966); WAHI,,A. C., '1Molecular Orbital Densities: Pictorial Studies,'' Science, 151, 961 (1966). (b) NORBURY, A., Edue. in C h a . , 5, 1 (1968).
(13) K ~ L T U N W., , BiopoZymers, 3, 665 (1965). Diac. Far. Soc., 16, 125 (1954). (14) ROBINSON, (15) ~ A I P M A N , W., J . CREM.EDUC.,46, 119 (1969) describes J., AND use in conjunction with FMO models; GOOTJES, BAKUWEL, G., "Dreiding Model of a Reversible Nitrogen Atom," J . CAEM.Enuc., 42, 407 (1965). (16) FIESEE,L. F., J. CREM.EDUC.,42, 409 (1965); FIESER, L. F., "Chemistry in Three Dimensions," Rineo Instrument Co.. 1963. (17) HENDRICKBON, H., AND SRERE,P., "MoIemIar Models of Metal Chelates to Illustrate Enzymatic Reactions," J. CHEM.EDUC.,45, 539 (1968). R., J. (18) BRuMLm, G., BARRETT, E., AND BAUMGARTEN, CAEM.EDUC.,41, 221 (1964); BARRETT,E., "Models Illustrrtting d Orbitals Involved in Multiple Bonding," C., J. CHEM.EDUC., 44, 147 (1967); BUMGARDNER, AND WAHL,G., JR.,"Framework Molecular Models to Illustrate Linnett's Double Quartet Theory," J. CHEM. Enuc., 45, 347 (1968). (19) GODPREY. J. C.. J . CHBM.EDUC.,42. 404 (1965). (20) LANDE, S., "Conformations of Peptides. Speculation Based m Moleculsr Models," J . CHEM.EDUC.,45, 587 (1968).
