What is Dalton's main achievement? What's his evaluation?

Establish atomism. 1803 inherited the naive atomism of ancient Greece and Newton's particle theory, and put forward atomism. The main points are as follows:

(1) Chemical elements are composed of inseparable particles-atoms. He believes that the atom is the smallest unit that cannot be separated in all chemical changes.

(2) The atomic properties and mass of the same element are the same, but the atomic properties and mass of different elements are different, and atomic mass is one of the basic characteristics of elements.

(3) When different elements are combined, atoms are combined in a simple integer ratio. The law of multiple is deduced and proved by experiments. If the mass of one element is fixed, the mass of another element in various compounds must be a simple integer ratio.

He was the first to determine the atomic weight, put forward the relative comparison method to calculate the atomic weight of various elements, and published the first atomic scale, which opened up a bright future for the later work of determining the atomic weight of elements.

In addition, Dalton's contribution to meteorology and physics is also outstanding. He is a meteorological fan. He observed the weather continuously from 1787 until a few hours before his death, and kept a weather diary of about 200,000 words. 180 1 also puts forward the law of gas partial pressure, that is, the total pressure of mixed gas is equal to the sum of the partial pressures of each component gas. He also measured the relationship between the density of water and temperature, the thermal expansion coefficient of gas and so on. Unfortunately, Dalton once stubbornly opposed Avon Gardlow's molecular theory preserved for him and passed it as a "joke".

In order to devote his whole life to the cause of science, Dalton never married and engaged in scientific research under harsh conditions. Britain only gave a pension at the appeal of famous European scientists, but Dalton saved it and gave it to the University of Manchester as a student scholarship.

1793, Dalton became a teacher of mathematics and natural philosophy at Manchester New College, relying on the knowledge of natural science obtained from the blind philosopher Goff. Shortly after he came to the college, he published Meteorological Observations and Essays, in which he described thermometers, barometers and devices for measuring dew points, and put forward an atomistic model in the appendix. But this book sells very little. 1794, Dalton was elected as a member of the Manchester Literature and Philosophy Association, which was founded by students from Priestley to discuss various issues other than theology and English politics. 65438+1October 3 1 He read "a special case of color vision" in the society. In this article, he first described the visual defects of color blindness, and summarized the special symptoms of color blindness observed from himself and many people. For example, besides blue and green, he can only see yellow. So color blindness is also called Dalton's disease by many people. 1799, the new college moved to York, and Dalton stayed in Manchester. By this time, he was already very famous and could make a living as a tutor.

1800, Dalton began to serve as the secretary of the society, and then studied the pressure of gas. He heated different gases with the same volume, and found that the change of gas pressure caused by temperature increase had nothing to do with the gas type. When the temperature changes are the same, the gas pressure changes are also the same. He actually came to the same conclusion as Charlie and Gay-Lussac later, but he didn't discuss the problem further. Dalton added water vapor to dry air in 180 1, and found that the pressure of one component in the mixed gas has nothing to do with the pressure of other components, and the total pressure is equal to the sum of the two pressures, that is, Dalton's law of partial pressure. In the same year, willaim henley, Dalton's closest friend, discovered that the amount of water-insoluble gas dissolved in water is proportional to the pressure, which is Henry's law. Later, Henry also observed that the same relationship existed for mixed gases, except that the pressure was replaced by the partial pressure of the gas. Dalton concluded from this study that dissolution is a purely physical process.

Dalton put forward a systematic theory of chemical atoms, introduced atoms and atomic weights, and made a pioneering contribution to the capacity analysis method.

Dalton suggested using simple symbols to represent the composition of elements and compounds.

Dalton was the first scientist to discover the phenomenon of color blindness.

Personality assessment

After the establishment of atomism, Dalton became famous in Britain and even Europe, and various honors came one after another. 18 16, Dalton was elected as an academician of the French Academy of Sciences. 18 17, Dalton was elected president of Manchester Literature and Philosophy Society; 1826, the British * * * awarded him the Science Gold Medal; 1828, Dalton was elected as a member of the Royal Society. Since then, he has been elected honorary academician of Berlin Academy of Sciences, honorary academician of Munich Academy of Sciences, honorary member of Moscow Science Association, and also won the title of Doctor of Law, the highest honor awarded to scientists by Oxford University at that time. In the face of honor, Dalton was calm and modest at first. Later, the honor became higher and higher, and he gradually became a little proud and conservative, moving towards a rigid and self-satisfied mentality. Fortunately, however, his love for science remained constant. Dalton's life is just as Engels pointed out: the new era of chemistry began with atomism, so Dalton should be the father of modern chemistry.

In terms of scientific theory, Dalton's atomism is another great progress in theoretical chemistry after lavoisier's oxidation theory. He revealed that the essence of all chemical phenomena is atomic motion, and defined the research object of chemistry, which is of great significance for chemistry to truly become a discipline. Since then, chemistry and its related disciplines have flourished. Philosophically, atomism reveals the relationship between chemical reaction phenomena and essence. After the birth of celestial evolution theory, it once again impacted the rigid view of nature at that time, which is of great significance to the development of scientific methodology, the formation of dialectical view of nature and the development of the whole philosophical epistemology.