Modem atomic theory

This system of nomenclature has withstood the impact of later experimental discoveries and theoretical developments that have since the time of Guyton de Morveau and Lavoisier greatiy altered the character of chemical thought, eg, atomic theory (Dalton, 1802), the hydrogen theory of acids (Davy, 1809), the duahstic theory (Berzehus, 1811), polybasic acids (Liebig, 1834), Periodic Table (Mendeleev and Meyer, 1869), electrolytic dissociation theory (Arrhenius, 1887), and electronic theory and modem knowledge of molecular stmcture. 

In 1808, an English scientist and schoolteacher, John Dalton, developed the atomic model of matter that underlies modem chemistry. Three of the main postulates of modem atomic theory, all of which Dalton suggested in a somewhat different form, are stated below and illustrated in Figure 2.1. 

With remarkable accuracy, Democritus in the fifth century B.C. set the stage for modem chemistry. His atomic theory of matter, which he formulated without experimental verification, still stands, more or less intact, and encapsulates the profound truth that nature s stunning wealth boils down to atoms and molecules. As science uncovers the mysteries of the world around us, we stand ever more in awe of nature s ingenious molecular designs and biological systems nucleic acids, saccharides, proteins, and secondary metabolites are four classes of wondrous molecules that nature synthesizes with remarkable ease, and uses with admirable precision in the assembly and function of living systems. 

Bauschlicher, C. W., Jr., 1995b, The Application of Ab Initio Electronic Structure Calculations to Molecules Containing Transition Metal Atoms in Modem Electronic Structure Theory, Part II, Yarkony, D. R. (ed.), World Scientific, Singapore. 

Modem atomic theory teaches that an atom is made up of positively charged protons, an equal number of negatively charged, i much, much tinier electrons, and varying numbers of uncharged j neutrons. Each element has a definite number of protons, and no other element can have that same number. For example, the element hydrogen has one, helium has two, lithium, three, and so on. The number of protons in the nucleus, or center, of each atom, is called the atomic number of the element. 

Alchemical thinking helped lead the Society to interpret the implications of modem atomic theory in a way that emphasized the unity of matter (and even of energy) that saw oneness, rather than disunity and distinctness, as a major substratum of atomic theory and that pushed to spiritualize this principle. This grasping for ever simpler and more basic unity is, of course, not so uncommon an impulse in twentieth-century physics. (Consider unified field theories, and even the Theory of Everything in more recent physics.) Alchemy allowed the scientists and Hermeticists of the Alchemical Society to re-enchant science by positing the origins of the modem scientific push for unity in ancient Hermetic spirituality. 

Though the Alchemical Society included academic chemists in its ranks, and productively worked out spiritual implications of modem science for them, none of the scientists in the Alchemical Society directly contributed to the major discoveries and theoretical innovations of modem atomic theory. But Ernest Rutherford and Frederick Soddy s laboratory at McGill was the site of a... 

Modem alchemy occultism and the emergence of atomic theory / Mark S. Morrisson. p. cm. 

Chemical analysis is an indispensable servant of modern technology whilst it partly depends on that modem technology for its operation. The two have in fact developed hand in hand. From the earliest days of quantitative chemistry in the latter part of the eighteenth century, chemical analysis has provided an important basis for chemical development. For example, the combustion studies of La Voisier and the atomic theory proposed by Dalton had their bases in quantitative analytical evidence. The transistor... 

What is the nature of the interaction between light and matter that causes certain wavelengths of light to be absorbed The answer lies in the structure of the atoms and molecules of which matter is composed. First consider atoms. The modem theory of the atom states that electrons exist in energy levels around... 

According to E. Stroker [1], it was not the Democritean atomistic theory of matter which was the precursor of the modem Daltonian atomic theory, as generally accepted, but the Aristotelian concept of minima naturalia, developed in the Middle Age. 

To change the hydrogen in a glass . F. Aston, Forty Years of Atomic Theory , in J. Needham and W. Pagel (eds.). Background to Modem Science (London Macmillan, 1938), 108. 

Millikan s experiment did not prove, of course, that (he charge on the cathode ray. beta ray, photoelectric, or Zeeman particle was e. But if we call all such particles electrons, and assume that they have e/m = 1.76 x Hi" coulombs/kg. and e = 1.60 x 10" coulomb (and hence m =9.1 x 10 " kg), we find that they fit very well into Bohr s theory of the hydrogen atom and successive, more comprehensive atomic theories, into Richardson s equations for thermionic emission, into Fermi s theory of beta decay, and so on. In other words, a whole web of modem theory and experiment defines the electron. The best current value of e = (1.60206 0.00003) x 10 g coulomb. 

While Lavoisier undoubtedly laid the foundations for the rapid rise of chemistry in the nineteenth century, his work was supported by that of other French chemists both before and after him.247 Without the Lavoisierian notion of the chemical element, it is unlikely that the chemical atomic theory and the laws of chemical combination would have been so widely accepted. However, a new perspective on the history of the concept of the chemical compound as the basis of modem chemistry suggests that it began long before Lavoisier and belongs to a different line of development involving the notion of chemical affinity .248-250... 

Zbigniew Plochocki, Modem Atomic Theory, Part 2 Electronic Stmcture and Chemical Properties of Atoms, 2nd ed., Wydawn. Szk. Pedagog., Warsaw, 1986. 

If you recall from the beginning of this chapter, some of the work that led to the development of the modem atomic theory was done by scientists Max Planck, Albert Einstein, Louis de Broglie, Werner Heisenberg, Niels Bohr, and Erwin Shrodinger. The first work centered around light (electromagnetic radiation), while the later work focused on the wave-like nature of matter. The AP test does not probe too deeply into the theoretical considerations of any of these scientists, but some calculations have popped up on previous tests. Therefore, let s turn our attention to some of the equations associated with these scientists work. 

Henry E. Roscoe, John Dalton and the Rise of Modem Chemistry (Macmillan, 1895) Frank Greenway, John Dalton and the Atom (Cornell University Press, 1966) Henry E. Roscoe and Arthur Harden, A New View of the Origin of Daltons Atomic Theory (Johnson Reprint, 1970) Elizabeth C. Patterson, John Dalton and the Atomic Theory (Doubleday, 1970). 

Which statements in Dalton s original atomic theory are now considered to be incorrect Describe how modem atomic theory differs from these statements. 

Whose work is credited with being the beginning of modem atomic theory (4.1)... 

Dalton s atomic theory (p. 89) Atheory proposed by John Dalton in 1808, based on numerous scientific experiments, that marked the beginning of the development of modem atomic theory. 

Dalton s 1808 version of the atomic theory of matter included five general statements (see Section 1.3). According to modem understanding, four of those statements require amendment or extension. List the modifications that have been made to four of the five original postulates. 

Ostwald, Wilhelm. (1853-1932). A German chemist who won the Nobel Prize for chemistry in 1909. He was considered to be a founder of modem physical chemistry. His work involved research in catalysis, the rates of chemical reactions, equilibrium, and conductivity of organic acids. He was an admirer of Mach and did not readily accept the atomic theory. He was educated at the University of Dorpat. 

Spectroscopy has played a vital role in the development of modem atomic theory. In addition, spectrochemical methods have provided perhaps the most widely... 

Dalton believed that atoms were solid, indivisible spheres, an idea we now reject. But he showed remarkable insight into the nature of matter and its interactions. Some of his ideas could not be verified (or refuted) experimentally at the time. They were based on the limited experimental observations of his day. Even with their shortcomings, Dalton s ideas provided a framework that could be modified and expanded by later scientists. Thus John Dalton is often considered to be the father of modem atomic theory. 

Dalton s work marked the beginning of the modem era of chemistry. The hypotheses about the nature of matter on which Dalton s atomic theory is based can be summarized as follows ... 

Modem chemistry began with Dalton s atomic theory, which states that all matter is composed of tiny, indivisible particles called atoms that all atoms of the same element are identical that componnds contain atoms of different elements combined in whole-nnmber ratios and that atoms are neither created nor destroyed in chemical reactions (the law of conservation of mass). 

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