Physical chemist Planck

Kinetics is concerned with many-particle systems which require movements in space and time of individual particles. The first observations on the kinetic effect of individual molecular movements were reported by R. Brown in 1828. He observed the outward manifestation of molecular motion, now referred to as Brownian motion. The corresponding theory was first proposed in a satisfactory form in 1905 by A. Einstein. At the same time, the Polish physicist and physical chemist M. v. Smolu-chowski worked on problems of diffusion, Brownian motion (and coagulation of colloid particles) [M. v. Smoluchowski (1916)]. He is praised by later leaders in this field [S. Chandrasekhar (1943)] as a scientist whose theory of density fluctuations represents one of the most outstanding achievements in molecular physical chemistry. Further important contributions are due to Fokker, Planck, Burger, Furth, Ornstein, Uhlenbeck, Chandrasekhar, Kramers, among others. An extensive list of references can be found in [G.E. Uhlenbeck, L.S. Ornstein (1930) M.C. Wang, G.E. Uhlenbeck (1945)]. A survey of the field is found in [N. Wax, ed. (1954)]. 

Several famous equations (Einstein, Stokes-Einstein, Nemst-Einstein, Nernst-Planck) are presented in this chapter. They derive from the heyday of phenomenological physical chemistry, when physical chemists were moving from the predominantly thermodynamic approach current at the end of the nineteenth century to the molecular approach that has characterized electrochemistry in this century. The equations were originated by Stokes and Nernst but the names of Einstein and Planck have been added, presumably because these scientists had examined and discussed the equations first suggested by the other men. 

The electrical aspects of membrane phenomena have long been of interest in science, and attracted the attention in the nineteenth century of famous physical chemists including Gibbs, Nernst, Planck, and Ostwald. Originally, this interest was connected to electrical phenomena in biological systems. In the present discussion attention is focused on membranes used in specific ion electrodes. 

Johannes Jacobus van Laar (The Hague, ii July 1860-Tavel sur Clarens, Lake Geneva, 9 November 1938), lecturer in physics in Amsterdam, published an enormous number of papers, mostly providing strict proofs of well-known thermodynamic and other results, criticising the simple but adequate deductions of van t Hoff, Nernst, and other physical chemists. His particular aversion was osmotic pressure. He produced a modified van der Waals equation in which the constants a and b are functions of temperature. His small book on thermodynamics is clear and interesting but disfigured by unnecessary polemics printed in heavy type. Max Planck used a function - /r in chemical thermodynamics. 

Skeptics criticized /i as an adjustable parameter, but when Planck chose h = 6.626 x 10 " J s he was able to fit the experimental to the experimental data for essentially an exact fit One of the main critics was Wilhelm Ostwald (1853-1932), a German physical chemist, who did not accept the atomistic theory and believed energy is continuous. While Planck also was skeptical about the existence of atoms, he had to adjust his thinking when his equation produced an exact fit to experiment based on quantization. In 1909, Ostwald was awarded the Nobel Prize for his work with catalysis. From this brief discussion, you can see that even at this late date Boltzmann s 1866 KMTG prediction of tiny gas atoms was not widely accepted. The term ultraviolet catastrophe was only used later by Paul Ehrenfest in 1911 and Planck was motivated mostly by the shift in wavelength peak with temperature due to his background in thermodynamics. 

Why this emphasis Schweber has portrayed Slater as a man who developed a deep feeling of both inferiority and competitiveness toward his European mentors and peers in the fields of atomic physics and quantum electrodynamics. Slater was not alone in this reaction, as Henry James made clear. Slater, like other American physicists and chemists, used his influence in Boston, New York, and Washington circles, as well as his position within his own institution, to build up American science in an area where Americans could take a competitive lead. 107 Donnan had written Lewis in 1921 that "you are making old Europe sit up some. If it wasn t for Planck, Einstein, Rutherford, and Bragg, we should be in a bad way." 108 But it was not enough for Europeans to sit up "some" they must be made to gawk. 

You have seen how scientists in the late nineteenth and early twentieth century developed and modified the atomic model. Changes in this model resulted from both experimental evidence and new ideas about the nature of matter and energy. By 1913, chemists and physicists had a working model that pointed tantalizingly in a promising direction. During the third decade of the twentieth century, the promise was fulfilled. In the next section, you will learn how physicists extended the ideas of Planck, Einstein, and Bohr to develop an entirely new branch of physics, and a new model of the atom. 

Hahn found the university s physicists more congenial than its chemists and regularly attended the physics colloquia. At one colloquium at the begiiming of the autumn term in 1907 he met an Austrian woman, Lise Meitner, who had just arrived from Vienna. Meitner was twenty-nine, one year older than Hahn. She had earned her Ph.D. at the University of Vieima and had already published two papers on alpha and beta radiation. Max Planck s lectures in theoretical physics had drawn her to Berlin for postgraduate study. 

There are no objections, I think, to accepting this historical interpretation the effort of many scientists, including among them eminent leaders such as Boltzmann, Planck, Einstein, Lorentz, and Debye, to name a few, later crowned by the new formulation of quantum mechanics, has provided the basis for a description of material systems which unifies physics and chemistry and constitutes the conceptual world in which we, theoretical chemists, are working. 

Looking in on these physics equations as a chemist, 1 am surprised in two different ways. First, the number of fundamental physical constants needed is surprisingly small. For example, the night sky still echoes with light from the Big Bang. The shape of this light can be described with just six numbers. In 2015, four years of data from the Planck satellite were processed and released, and only minor tweaks to those six numbers were needed to explain all that data. Those six numbers work very, very well. 

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