Atomic theory Greek

Dalton s application of the Greek atomic theory to the facts established by the analyses of compounds enabled him to attach to each element a number which he called the atomic weight of the element, and to summarise all the facts concerning the compositions of compounds in the statement, that the elements combine in the ratios of their atomic weights, or in the ratios of whole multiples of their atomic weights. All the investigations which have been made into the compositions of compounds, since Dalton s time, have confirmed the generalisation which followed from Dalton s application of the atomic theory. 

BCB Roman poet and philosopher Lucretius writes on Greek atomic theory. 

In Chapter I., I gave a sketch of the atomic theory of the Greek thinkers. The founder of that theory, who flourished about 500 B.C., said that every substance is a collocation of a vast number of minute particles, which are unchangeable, indestmctible, and impenetrable, and are therefore properly called atoms, that the differences which are observed between the qualities of things are due to differences in the numbers, sizes, shapes, positions, and movements of atoms, and that the process which occurs when one substance is apparently destroyed and another is produced in its place, is nothing more... 

By the end of the seventeenth century, then, scientists were not really any closer to enumerating the elements than were the Greek philosophers. Yet a hundred years later the British chemist John Dalton (1766-1844) wrote a textbook that outlined a recognizably modern atomic theory and gave a list of elements that, while still very incomplete and sometimes plain wrong, is in content and in spirit a clear precursor to today s tabulation of the hundred and more elements. Why had our understanding of the elements changed so fast ... 

In the classical era in Europe, the theory and practice of chemistry were pursued mainly by the ancient Greeks, who made many important discoveries in metallurgy in particular and who are also credited with proposing the earliest version of the atomic theory. The Greek chemical tradition declined when mysticism displaced the observational approach in the second century of the Common Era, and subsequently was largely lost in Europe after the fall of Rome in 410 c.E. In the 11th. century c.E., the quasiscience of alchemy returned to Europe via the Arabs, who also introduced Persian, Indian, and Chinese influences. 

To Leucippus and Democritus the Greeks and the Western world are indebted for the first clearly defined atomic theory of matter. Leucippus was the teacher of Democritus,... 

Sala was also an important champion of the introduction of the chemical medicines. Sala s description of fermentation, as an intimate movement of elementary particles which tend to group themselves in a different order to make new compounds, is evidence of a concept doubtless derived from the atomic theory of the Greeks, and differs from the concept of chemical action in the nineteenth century mainly by lacking qualitative and quantitative definition. 

In 400 B.C., the Greeks explained that all matter was made of fire, earth, water, and air. A Greek philosopher, Democritus (460-370 B.C.), reasoned that matter was made of small, indivisible particles called atomos. Though the Greeks did not use experiments to test their ideas, the following scientists did, basing their atomic theories on experimental data ... 

Ancient philosophers in Greece, India, China, and Japan speculated that all matter was composed of four or five elements. The Greeks thought that these were fire, air, earth, and water. Indian philosophers and Aristotle from Greece also thought a fifth element—"aether" or "quintessence"—filled all of empty space. The Greek philosopher Democritus thought that matter was composed of indivisible and indestructible atoms. These concepts are now known as classical elements and classical atomic theory. 

Pasteur in Paris and was one of the pioneers of modern atomic theory, proposed the name phene . The word phene (from the Greek phainen , to shine) was proposed because benzene burns with a bright flame. Although it was not adopted for benzene, this word is now used in a number of names of arenes, such as phenol, phenanthrene, etc. 

In the past 200 years a great deal of experimental evidence has accumulated to support the atomic model. This theory has proved to be both extremely useful and physically reasonable. When atoms were first suggested by the Greek philosophers Democritus and Leucippus about 400 B.c., the concept was based mostly on intuition. In fact, for the following 20 centuries, no convincing experimental evidence was available to support the existence of atoms. The first real scientific data were gathered by Lavoisier and others from quantitative measurements of chemical reactions. The results of these stoichiometric experiments led John Dalton to propose the first systematic atomic theory. Dalton s theory, although crude, has stood the test of time extremely well. 

Although the Greek philosophers Democritus (460-370 Bc) and Epicurus (341-270 Bc) presented views of nature that included atoms, many hundreds of years passed before experimental studies could establish the quantitative relationships needed for a coherent atomic theory. In 1808, John Dalton published A New System of Chemical Philosophy in which he proposed that... 

In 1808, John Dalton, an English school teacher, used the Greek concept of the atom and the law of definite proportions, the law of conservation of mass, and the law of multiple proportions to develop an atomic theory. Dalton believed that a few kinds of atoms made up all matter. 

While a fair amount of Democritus s ideas do not agree with modern atomic theory, his belief in the existence of atoms was amazingly ahead of his time. Despite this, his ideas did not turn out to be a major step toward our current understanding of matter. Over time, Democritus s ideas were met with criticism from other philosophers. What holds the atoms together they asked. Democritus could not answer the question. Other criticisms came from Aristotle (384-322 b.c.), one of the most influential Greek philosophers. Aristotle is shown in Figure 4-3. He rejected the atomic theory entirely... 

Dalton, John. (1766-1844). The first theorist since the Greek philosopher Democritus to conceive of matter in terms of small particles. The founder of the atomic theory on which all succeeding chemical investigation has been based (1807). His essential concept of the indivisibility of the atom was not called into question until 1910 when radioactive decay was established by Rutherford. Dalton s theories relating to pressures of gases and atomic combinations led to the basic generalizations stated in the law of multiple proportions, the law of constant composition, and the law of conservation of matter. 

It is true that the ancient Greeks were concerned with knowledge for its own sake. They even had a well-developed atomic theory which was in many ways similar to atomic theory today. But the Greeks were not fond of doing experimental work, so their theory just stayed on the books and was never developed. 

The ancient Greek philosophers Leucippus and Democritus beheved that atoms existed, but they had no idea as to their nature. Centuries later, in 1803, the English chemist John Dalton, guided by the experimental fact that chemical elements cannot be decomposed chemically, was led to formulate his atomic theory. Dalton s atomic theory was based on the assumption that atoms are tiny indivisible entities, with each chemical element consisting of its own characteristic atoms. ... 

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