Raji Heyrovska

Physical electrochemistry of strong electrolytes based on partial dissociation and hydration : Quantitative interpretation of the thermodynamic properties of NaCl(aq) from zero to saturation

The authors earlier quantitative interpretations of the nonideal properties of strong electrolytes in aqueous solutions have now been successful extended to cover the whole range of concentrations. It is shown that (i) nonideality, expressed as osmotic and activity coefficients, is due to the incomplete dissociation and hydration of the electrolyte, (ii) the hydration numbers at the vapor/solution interface and bulk regions are different, (iii) the degree of dissociation has a minimum value at the molality at which the mean ionic activity is unity, and (iv) the molal volume and the molal dissociation constant depend on the volumes of ions and ion pairs. Simple quantitative relations, supporting graphs, and tables of data for NaCl(aq) at 25°C are provided.

The Golden ratio, ionic and atomic radii and bond lengths

This work arose from the authors finding that the ratio of the radius of hydrogen, estimated recently (C.H. Suresh, N. Koga, J. Phys. Chem. A, 105, 5940 (2001)) by density functional methods, to the ground state Bohr radius is the Golden ratio, which operates in a variety of natural phenomena. It is found that the Golden ratio indeed plays a quantitative role in atomic physics. The interesting results are (1) that it arises in atomic dimensions due to the electrostatic forces between negative and positive charges; (2) that the energy of atomic hydrogen is actually equivalent to the energy of the simplest atomic condenser with the Golden mean capacity; (3) that the origin of two terms in the Rydberg equation for absorption and emission is in fact in the ground state term; (4) that all atoms can be assigned definite values of cationic and anionic radii based on the Golden ratio and covalent radii; (5) that these radii are additive and explain quantitatively bond lengths like those of alkali halides, of hydrides of many elements and of many other bonds, whether covalent or ionic or both; and (6) that the work functions of alkali metals can be evaluated using the bond lengths.This work arose from the authors finding that the ratio of the radius of hydrogen, estimated recently (C.H. Suresh, N. Koga, J. Phys. Chem. A, 105, 5940 (2001)) by density functional methods, to the ground state Bohr radius is the Golden ratio, which operates in a variety of natural phenomena. It is found that the Golden ratio indeed plays a quantitative role in atomic physics. The interesting results are (1) that it arises in atomic dimensions due to the electrostatic forces between negative and positive charges; (2) that the energy of atomic hydrogen is actually equivalent to the energy of the simplest atomic condenser with the Golden mean capacity; (3) that the origin of two terms in the Rydberg equation for absorption and emission is in fact in the ground state term; (4) that all atoms can be assigned definite values of cationic and anionic radii based on the Golden ratio and covalent radii; (5) that these radii are additive and explain quantitatively bond lengths like those of alkali halides, of hyd...

Adsorption in polarographic reversible electrode reactions

Summary A reinterpretation of the adsorption pre- and postwaves in polarographic reversible electrode reactions has been put forward. Both these anomalous waves are attributed to reversible surface redox systems where electron transfer takes place in the adsorbed state in contrast to the main wave, the half-wave potential of which corresponds to the normal redox potential. The half-wave potentials of these surface redox systems are determined by the interaction between the adsorbed species and the electrode. Supporting experimental evidence has been provided.

Effective radii of alkali halide ions in aqueous solutions, crystals and in the gas phase and the interpretation of stokes radii

Abstract The effective radii of alkali halide ions have been evaluated from data on ion-water internuclear distances and equilibrium interionic distances in crystals and in the gas phase. The Stokes radius of an ion has been shown to be equal to the product of the effective molecular radius of water and the ratio of the coefficient of viscosity of water adjacent to the ions to that of pure water. The Stokes radius of a water molecule has been found to be the same as its (intrinsic) radius.

Structures of the Molecular Components in DNA and RNA with Bond Lengths Interpreted as Sums of Atomic Covalent Radii

The author has found recently that the lengths of chemical bonds are sums of the covalent and or ionic radii of the relevant atoms constituting the bonds, whether they are completely or partially covalent or ionic. This finding has been tested here for the skeletal bond lengths in the molecular constituents of nucleic acids, adenine, thymine, guanine, cyto- sine, uracil, ribose, deoxyribose and phosphoric acid. On collecting the existing data and comparing them graphically with the sums of the appropriate covalent radii of C, N, O, H and P, it is found that there is a linear dependence with effectively unit slope and zero intercept. This shows that the bond lengths in the above molecules can be interpreted as sums of the relevant atomic covalent radii. Based on this result, the author has presented here the atomic structures of the above mole- cules in terms of the atomic radii (for the first time).The interpretation by the author in recent years of bond lengths as sums of the relevant atomic or ionic radii has been extended here to the bonds in the skeletal structures of adenine, guanine, thymine, cytosine, uracil, ribose, deoxyribose and phosphoric acid. On examining the bond length data in the literature, it has been found that the averages of the bond lengths are close to the sums of the corresponding atomic covalent radii of carbon, nitrogen, oxygen, hydrogen and phosphorus. Thus, the conventional molecular structures have been resolved here, for the first time, into probable atomic structures.

The Golden Ratio in the Creations of Nature Arises in the Architecture of Atoms and Ions

The Golden ratio, φ = a/b = (a + b)/a, where a and b are the Golden sections of their sum, has long been known to operate in a variety of the creations of Nature, ranging from the mollusks in the oceans to the spiral galaxies in the Universe. Recently, while researching for the exact values of ionic radii and for the significance of the ionization potential (I H = e/2κa B ) of hydrogen, it was found that a B , the Bohr radius has two Golden sections pertaining to the electron and proton. Further, φ was also found to be the ratio of the anionic to cationic radii of an atom (A), their sum being the covalent bond length, d(AA). With these radii many bond lengths were shown to be sums of the covalent and or ionic radii, whether partially or fully ionic or covalent. For example, the crystal ionic distances of all alkali halides were shown to be sums of the φ-based ionic radii. When the ion-water distances were plotted against the above φ-based ionic radii, linear relations were found. This enabled the assignment of exact ionic radii in water, and to show that the hydration bond lengths of O (oxygen coordination bond) with cations and of H (hydrogen bond) with anions are constants. Simple integral multiples of the cationic radius, d(H + ) = d(HH)/φ 2 , and the covalent radius of H, were found to quantitatively account for the lengths of the hydrogen bonds in many inorganic and biochemical groups.

An estimation of the ionization potentials of actinides from a simple dependence of the aqueous standard potentials on the ionization potentials of elements including lanthanides

It was found recently that the ionization potentials and electron affinities of elements in the gaseous state are linked to the standard potentials of their principal oxidation states in aqueous solutions by simple linear relations. These relations are characteristic for each group of elements of the periodic table. In the case of the actinides, in the absence of adequate data on their ionization potentials, the linear relation obtained for the group IIIB elements (including lanthanides) has been found useful for estimating them using the available data on their standard oxidation potentials (obtained in most cases by radio-polarography).

Absolute Potentials of the Hydrogen Electrode and of Aqueous Redox Couples

The observation here that conventional aqueous standard potentials based on that of the standard hydrogen electrode (SHE) vary linearly with the gaseous ionization potentials for many groups of elements has enabled obtaining the absolute potential of the SHE and thereby the absolute aqueous standard potentials of elements. Depending on the slopes of the lines, redox couples have been classified into several aqueous groups.

Aqueous Redox Potentials Found to be Inversely Proportional to the Bohr Radius

The author found recently that the covalent, van der Waals and valence shell radii of atoms vary linearly with their respective Bohr radii obtained from their gaseous ionization potentials. Earlier, the ratio of the standard redox potential (with SHE = 0) to the ionization potential had been found to vary linearly with the latter. Here, the standard potentials are shown to be indirectly proportional the Bohr radius and directly proportional to the ionization potentials. This yielded the absolute potential of the SHE and thereby the absolute aqueous redox potentials of elements. These have been presented here in a Table.

Present State of Women in Physics in the Czech Republic

In the year 2005, the World Year of Physics, mention must be made of Albert Einstein and his stay in Prague in the former Czechoslovakia (now the Czech Republic). Here he spent two important years (1911–1912) along with his wife Mileva and two sons. During this period, the basic thoughts on general relativity received a more definite form. At this conference on women in physics, we want to emphasize the role of Mileva, who was supposed to have contributed substantially to his scientific outputs. She deserves her place in the World Year of Physics 2005. Among the distinguished Czech women physicists currently in prominent positions are Dr. M. Glogarova, the vice-director of the Institute of Physics of the Czech Academy in Prague, and Prof. J. Musilova, who was, until recently, the vice-dean of the Faculty of Sciences of Masaryk University in Brno. At the professorial level, the number of women does not exceed 5%. Women holding a DSc degree are fewer than 1%, and those with a PhD degree are less than 20%. Of the members of scientific bodies at institutes or universities, less than 10% are women. In general, there has not been much improvement since the First IUPAP International Women in Physics Conference in 2002. This shows that more effective measures are needed for achieving the equality of men and women at all levels of physics careers (as in other branches of the natural sciences). Women drop out despite their talents due to lack of consideration, appreciation, and encouragement. In the matters of education, employment, research and salary, serious regard must be given to time lost with maternity and child and family care. Concerned authorities are urged to give intellectually capable women with aspirations in physics, as well as in other branches of science, all the opportunities equal to those of men.