The Development of Dalton`s Atomic Theory as a Case Study in the History of Science: Reflections for Educators in Chemistry

The inclusion of the history of science in science curricula-and specially, in the curricula of science teachers-is a trend that has been followed in several countries. The reasons advanced for the study of the history of science are manifold. This paper presents a case study in the history of chemistry, on the early developments of John Dalton`s atomic theory. Based on the case study, several questions that are worth discussing in educational contexts are pointed out. It is argued that the kind of history of science that was made in the first decades of the twentieth century (encyclopaedic, continuist, essentially anachronistic) is not appropriate for the development of the competences that are expected from the students of sciences in the present. Science teaching for current days will benefit from the approach that may be termed the ""new historiography of science"".

Atomism: Dr. Tyndall's atomic theory of the universe examined and refuted.

Mode of access: Internet.

Foundations of the atomic theory: comprising papers and extracts by John Dalton, William Hyde Wollaston, M. D., and Thomas Thomson, M. D. (1802-1808)

Mode of access: Internet.

Calculation of nondifferential properties for atomic ground states /

A new method for sampling the exact (within the nodal error) ground state distribution and nondiflPerential properties of multielectron systems is developed and applied to firstrow atoms. Calculated properties are the distribution moments and the electronic density at the nucleus (the 6 operator). For this purpose, new simple trial functions are developed and optimized. First, using Hydrogen as a test case, we demonstrate the accuracy of our algorithm and its sensitivity to error in the trial function. Applications to first row atoms are then described. We obtain results which are more satisfactory than the ones obtained previously using Monte Carlo methods, despite the relative crudeness of our trial functions. Also, a comparison is made with results of highly accurate post-Hartree Fock calculations, thereby illuminating the nodal error in our estimates. Taking into account the CPU time spent, our results, particularly for the 8 operator, have a relatively large variance. Several ways of improving the eflSciency together with some extensions of the algorithm are suggested.

A general survey of the present status of the atomic structure problem : report of the Committee on Atomic Structure of the National Research Council /

Cover-title.

El naturalismo científico en la obra de John Tyndall: Fragments of science

El análisis de los ensayos de John Tyndall, Fragments of Science, permite identificar la teoría atómica, el principio de conservación de la energía y el evolucionismo darwinista como los elementos constitutivos del andamiaje teórico del naturalismo científico. Así, en su ensayo “On the Study of Physics” se resumen sus brillantes facetas como educador y divulgador científico, desarrolladas fundamentalmente en el seno de la Royal Institution. En la lectura “On Force”, Tyndall da por finalizada la controversia Joule- Mayer sobre la primacía del descubrimiento del principio de conservación de la energía, a la vez que plantea algunas de las claves de la lucha por el liderazgo en el seno de la comunidad científica. El discurso presidencial ante la British Association de 1874 en Belfast ejemplifica el coraje de Tyndall en su empeño por demarcar los territorios de la ciencia y la religión, a la luz de los nuevos desafíos científicos. En el trasfondo subyacen los procesos de secularización de la sociedad y de profesionalización de una comunidad científica heterogénea. El compromiso cívico que Tyndall demuestra en “The Belfast Address” es digno corolario de una vida y obra que permite situarlo como paradigma de lo que, en la terminología de Turner, se ha dado en denominar científico público.

Nuclear sizes and the isotope shift

Darwin-Foldy nuclear-size corrections in electronic atoms and nuclear radii are discussed from the nuclear-physics perspective. The interpretation of precise isotope-shift measurements is formalism dependent, and care must be exercised in interpreting these results and those obtained from relativistic electron scattering from nuclei. We strongly advocate that the entire nuclear-charge operator be used in calculating nuclear-size corrections in atoms rather than relegating portions of it to the nonradiative recoil corrections. A preliminary examination of the intrinsic deuteron radius obtained from isotope-shift measurements suggests the presence of small meson-exchange currents (exotic binding contributions of relativistic order) in the nuclear charge operator, which contribute approximately 1/2%.

Hadronic vacuum polarization and the Lamb shift

Recent improvements in the determination of the running of the fine-structure constant also allow an update of the hadronic vacuum-polarization contribution to the Lamb shift. We find a shift of -3.40(7) kHz to the 1S level of hydrogen. We also comment on the contribution of this effect to the determination by elastic electron scattering of the rms radii of nuclei.

Walter Charleton (1620 - 1707) e sua Teoria Atômica

Several authors in the 17th century used the atomic hypothesis to explain observable phenomena. This paper analyzes some ideas about chemical transformation proposed by the English physician Walter Charleton. In Physiologia Epicuro-Gassendo-Charltoniana (London, 1654), Charleton examined philosophical aspects of the atomic theory, and suggested that the best explanation for all natural phenomena would be only in terms of atoms and their motions. Sometimes, however, he had to attribute to the atoms some kind of "internal virtue", to explain more complex properties of the matter. His idea of "element", and the little use of experimentation and quantification, also limited the range of Charleton's theory.

Irving langmuir: o milagre da ciência

Irving Langmuir received the Nobel Prize in Chemistry in 1932 "...for his outstanding discoveries and investigations within the field of surface chemistry", according to the Swedish Academy. However, few people know that his work comprises other very important contributions, and not only for chemistry, such as the discovery of plasma, the atomic hydrogen, the pure thermoionic phenomenon, the development of the cloud seeding technique for weather modification, among many others. This paper summarizes Langmuir's most important discoveries and theories, with an especial mention for his practical inventions and his work on the atomic theory.

O comportamento do elétron: uma análise do efeito compton e da relação de Broglie

The De Broglie's relation was a fundamental step in the development of a wave nature for matter. Therefore, we have examined it from the perspective of the new atomic theory. This relation makes successful predictions of the stable energy levels for electrons orbiting a nucleus. The formulation of the de Broglie's relation is a fundamental application of the theory of wave-particle duality for a material particle. In this work, the direct demonstration employing the equations E = mc² and E = hcλ, was avoided. We provide a complete analysis of this relation considering features of the special theory of relativity.

Os químicos ocultos e sua extraordinária jornada ao mundo dos átomos

At the end of the XIX century, a group of chemists and theosophists called the Occult Chemists suggested it would be possible "to see" atoms by clairvoyance. In a meditative situation, a skilled person in contact with a substance would thus be able to see magnified atoms and molecules, as well as its internal structure. Annie Besant was the leader of this group and, together with Curuppumullage Jinarajadasa, Charles Leadbeater and Bertram Keightley, they devised an extraordinary atomic theory in which atoms consisted of smaller, indivisible units of energy called anu. In this paper, we present the fundamental principles of this unusual theory.

Using 3D Animations in Teaching Chemistry

This paper discuss possibilities of use of 3D animation as a tool for teaching Chemistry support. The research proposes to investigate the conception process and development of educational animations to use in a Blended Learning environment in undergraduate chemistry. Associated with general chemistry teachers, were raised the demands and difficulties on the content transmission, and the most relevant topics, about "Atomic Theory" with propose to create appropriate animations to meeting needs of themes. Thinking about offering more dynamic materials, we elaborate animations in a format of "micro-documentary", with a length between 4 and 7 minutes. We use the narration aloud to the subject-matter understanding, leaving the external text as a complement of the animation. The conclusions are positives, students accepted well the format and they proved are able to remember, organize and systematize several information presented in animations. These skills don't ensure knowledge acquisition, but may be considered prerequisites to learning occur.

Essai critique sur l'hypothèse des atomes dans la science contemporaine,

"La première édition ... a été publiée dans les Annales de l'Université de Lyon, 1895."

Versuch einer genetischen Entwickelung der mechanischen Krystallisations-Gesetze : nebst vorläufigen Erörterungen über die mechanischen Bedingungen des dreifachen Aggregatzustandes der Körper überhaupt /

Mode of access: Internet.