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For the textbook, chapter, and section you specified we found
Dancing Crystals: A Dramatic Illustration of Intermolecular ForcesDonald W. Mundell Crystals of naphthalene form on the surface of an acetone solution and dance about in an animated fashion illustrating surface tension, crystallization, and intermolecular forces. Additional experiments reveal the properties of the solution and previous demonstrations of surface motion are explored. Mundell, Donald W. J. Chem. Educ.2007, 84, 1773.
Aromatic Compounds |
Liquids |
Molecular Mechanics / Dynamics |
Molecular Properties / Structure |
Physical Properties |
Surface Science |
Noncovalent Interactions
A2: Element or Compound?Marilyne Stains and Vicente Talanquer Particulate questions are used to investigate the mental association between the concepts of molecule and compound in chemistry students with different levels of academic preparation. A significant proportion of students misclassify molecular elements as chemical compounds, and this association is stronger in students with higher levels of preparation. Stains, Marilyne; Talanquer, Vicente. J. Chem. Educ.2007, 84, 880.
Dipole ForcesEd Vitz, John W. Moore A section of ChemPrime, the Chemical Educations Digital Library's free General Chemistry textbook.
Molecular Properties / Structure |
Noncovalent Interactions
Penicillin and Vitamin B12William F. Coleman The WebWare Molecules for July are mentioned in the article "The History of Molecular Structure Determination Viewed through the Nobel Prizes", by Jensen, Palenik, and Suh. One of the recipients discussed, Dorothy Crowfoot Hodgkin, won the Nobel Prize in Chemistry in part for determining the structures of penicillin and vitamin B12.
Molecular Modeling |
Molecular Properties / Structure
Molecular Model of Creatine SynthesisWilliam F. Coleman The featured molecules for this month come from the paper Creatine Synthesis: An Undergraduate Organic Chemistry Laboratory Experiment by Andri Smith and Paula Tan on the synthesis of creatine in introductory organic chemistry. This synthesis is sufficiently straightforward to be used in non-majors and general chemistry courses. The structures illustrate some of the limitations associated with the computation of molecular structure. The two adenosine phosphates ADP and ATP exhibit a large number of conformations due to rotation of the adenine system around the bond to the ribose ring, multiple rotational conformations in the phosphate groups, the ionic state of the compound, and the interaction with the solvent or another species such as creatine. The structures that are given for ADP and ATP are derived from PM3MM calculations and are very similar to those derived using the UFF force field. Sarcosine, creatine, and creatine phosphate were treated using the model chemistry B3LYP/6-31+G(d). Perhaps the most interesting structural feature is found in the small molecule cyanamide. Observant students might notice in the Web-based structure that the NCN grouping in cyanamide is non-linear, with an angle of about 177°. This is found for essentially all levels of theory we examined up through the G2 combined model. For students who do notice this deviation from linearity it is useful to ask them whether they are surprised, ask them to defend their answer, send them to the literature to see whether such behavior is seen for cyanamide in other phases (it is), and finally to speculate on possible explanations for the observed non-linearity.
