Resonance in the Hydrogen Molecule

In a recent paper (1) Mueller and Eyring have discussed the normal state of the hydrogen molecule with use of a variation function constructed in the usual Heitler-London manner, except with replacement, for each electron, of the hydrogen-atom function about atom a, exp(-Z'ra/ao), byt the more complex function φa = exp(-Z'ra/ao)exp(-Z''rb/a0). The authors call one-electron functions of this sort semilocalized orbitals. They have compared the value of the bond energy calculated for the wave function [...], with those given by the simple atomic orbital method and the molecular orbital method, and have pointed out that there is an improvement to 4.20 ev, from the values 3.76 ev and 3.60 ev, respectivel

Interatomic Distances in Covalent Molecules and Resonance between Two or More Lewis Electronic Structures

In a paper to be published in the Zeitschrift für Kristallographie, Professor M. L. Huggins and I have formulated tables of radii for use in crystals containing electron-pair bonds. With the aid of these tables, we have also constructed a table of radii (table 1) for non-metallic atoms in covalent molecules. These radii are designed especially for purely covalent compounds, in which fluorine forms one electron-pair bond, oxygen two, nitrogen three, etc., but they are applicable also to other compounds, such as (CH3)3N:O:, with the following exception. The radii given for As, Se, Br, Sb, Te and I are to be used for these atoms with a covalence of one, two or three; for a covalence of four slightly smaller values ("tetrahedral radii") are to be used. The change is probably due to a change in the nature of the bond eigenfunctions involved

The effects of strontium-90 on mice

On Sept. 19, 1958 there was published in Science a paper by Dr. Miriam P. Finkel of Argonne National Laboratory in which she communicated her observations on the effects of strontium-90 injected into mice on life expectancy and on incidence of tumors of bone and blood-forming tissues.(1) She discussed the question of whether or not the effects are proportional to the amount of injected strontium-90 at low doses, and reached the conclusion that it is likely that there is a threshold with value for man between 5 and 15 μc. (as compared with the present average value from fallout, about 0.0002 μc., and the predicted steady-state value from fallout for testing of nuclear weapons at the average rate for the past five years, about 0.02 μc.). Her paper ends with the sentence "In any case, the present contamination with strontium-90 from fallout is so very much lower than any of these levels that it is extremely unlikely to induce even one bone tumor or one case of leukemia.

A wave-mechanical treatment of the Mills-Nixon effect

The Mills-Nixon effect has been examined by a very simple wave-mechanical treatment. This has led to the conclusion that the effect of saturated side rings upon the ratio of the coefficients of the wave-functions of the two Kekulé structures is relatively small, being not more than about 6 per cent., and that the benzene ring retains the greater part of its stabilising resonance energy. Nevertheless, making the reasonable assumption that the ratio of the activation energies, for reaction as either one of the two Kekulé structures, depends upon the square of the ratio of coefficients, it is possible to account for the experimental facts. The effect which bending two valencies has upon the angles between the other valencies projecting from the benzene ring is found to be very small

The Additivity of the Energies of Normal Covalent Bonds

The chemical bond between two identical atoms, as in the molecules H2, Cl2, etc., may be considered as an example of a normal covalent bond, involving an electron pair shared by the two atoms. The wave function representing this bond cannot necessarily be closely approximated by a function of the Heitler-London type, with the electrons staying on different atoms, but may contain ionic terms, corresponding to the two electrons of the bond on the same atom, the term representing the configuration A+A- occurring, of course, with the same coefficient as that for A -A +. The contribution of these ionic terms to the wave function for the normal state of the hydrogen molecule has been discussed by Slater [1]

Molecular Architecture and Biological Reactions

Answers to many basic problems of biology—nature of growth, mechanism of duplication of viruses and genes , action of enzymes, mechanism, of physiological activity of drugs, hormones, and vitamins, structure and action of nerve and brain tissue—may lie in knowledge of molecular structure and intermolecular reactions

Superoxide Dismutase Activity within Caribou Serum as an Indicator of Copper Status

Copper concentrations measured in liver are the gold standard for evaluating the copper status of ruminants. For live ruminants, measuring copper status is problematic because serum copper concentrations fluctuate and are not consistently correlated to liver copper values. In an attempt to establish an accurate evaluation of copper status from serum in caribou, we examined the correlation between liver copper concentrations and superoxide dismutase (SOD), which uses the oxidation and reduction reactions of a bound copper ion in order to catalyze superoxide radicals. Our study focuses on SOD activity in the serum of 16 individual adult female caribou and compares that to known copper levels within the liver. Determining copper levels in ruminants has proven difficult and currently a true proxy to determine liver copper levels in a live animal is unknown

Academic Research as a Career

The real student in science — with a consuming curiosity into the laws of nature and with top scholastic status — may be of the caliber required to become the recognized authority in some fiel

Analogies between Antibodies and Simpler Chemical Substances

Because of his contributions in the study of antibodies, Linus Pauling was chosen as the first Harrison Howe lecturer. His talk, given below, was delivered before the Rochester Section of the American Chemical Society, Feb. 4, in Rochester, Ν. Υ