germination period
From ancient times to BC 1500, humans learned to make pottery with clay, burn metal with ore, make wine with grain, and dye fabrics such as silk and flax with fire. These are the earliest chemical processes that have not formed chemical knowledge after a long period of exploration under the direct inspiration of practical experience, but they are just the embryonic stage of chemistry. In ancient times, in order to survive, primitive humans discovered and used fire in the struggle against various disasters in nature. Primitive humans began to use fire, from barbarism to civilization, and at the same time began to understand and transform natural substances by chemical methods. Combustion is a chemical phenomenon. The discovery and utilization of fire has improved the living conditions of human beings and made them smart and powerful. )
After mastering fire, humans began to eat cooked food; Then humans discovered some material changes one after another. For example, burning charcoal fire on emerald malachite and other copper ores will produce red copper. In China, the bronze society began to transform during the Spring and Autumn Period and the Warring States Period, and the social changes triggered by the iron Niu Geng promoted the development of chemistry. [3]
In this way, in the process of gradually understanding and utilizing the changes of these substances, human beings have made products of use value to human beings. Humans gradually learned to make pottery and smelt; Later, I learned wine making, dyeing and so on. These products, which are processed and transformed from natural materials, have become symbols of ancient civilization. On the basis of these production practices, ancient chemical knowledge sprouted.
Dan medicine period
From about 1500 BC to 1650 AD, chemistry was controlled by alchemy and alchemy. In order to obtain immortal elixir or gold symbolizing wealth, alchemists and alchemists began the earliest chemical experiments, and then books recording and summarizing alchemy appeared one after another. Although both alchemists and alchemists ended in failure, in the process of refining elixir and exploring the method of "turning stone into gold", they realized the mutual transformation between substances by artificial methods, accumulated the conditions and phenomena of chemical changes of many substances, and accumulated rich practical experience for the development of chemistry.
The word "chemistry" that appeared at that time meant "alchemy". But with the decline of alchemy and alchemy, people see its absurd side more and more. In fact, chemical methods have been properly played in medicine and metallurgy, and the development of pharmacology and metallurgy at home and abroad has prepared rich materials for chemistry to become a science. At the same time, the properties of various substances, especially the properties of mutual reaction, are further classified and studied. All these laid the foundation for the emergence of modern chemistry, and many instruments and methods are still used in today's chemical experiments after improvement. An alchemist invented gunpowder in his experiment, discovered some elements, made some alloys, and made and purified many compounds. These achievements are still in use today.
Phlogiston period
This period, from 1650 to 1775, is the gestation period of modern chemistry. With the accumulation of metallurgical industry and laboratory experience, people sum up perceptual knowledge and make theoretical research on chemical changes, making chemistry a branch of natural science. British chemist Boyle pointed out the scientific concept of chemical elements, which marked the beginning of this stage. Then chemistry was liberated from alchemy by phlogiston. According to phlogiston theory, combustible can burn because it contains phlogiston, and the combustion process is the process in which combustible releases phlogiston. Although this theory is wrong, it unifies a large number of chemical facts under one concept and explains many chemical phenomena.
During the more than one hundred years when phlogiston theory prevailed, chemists did a lot of experiments to explain various phenomena, discovered the existence of various gases, and accumulated more new knowledge about substance transformation. In particular, phlogiston theory holds that chemical reaction is a process of transferring one substance to another, and substances are conserved in chemical reaction, which lays the foundation of modern chemical thought. This period not only prepared for the development of modern chemistry in scientific practice, but also in thought, and became the gestation period of modern chemistry.
/kloc-Since the beginning of the 6th century, industrial production in Europe has flourished, which has promoted the establishment and development of pharmaceutical chemistry and metallurgical chemistry. Make alchemy turn to life and practical application, and then pay more attention to the study of substance and chemical change itself. After the scientific concept of elements was established, the scientific oxidation theory and the law of mass conservation were established through the accurate experimental study of combustion phenomenon, and then the law of constant ratio, law of multiple proportions and the law of combined quantity were established, which laid the foundation for the further scientific development of chemistry.
period of expansion
This period, from 1775 to 1900, is a period of modern chemistry development. 1775 or so, lavoisier expounded the oxidation theory of combustion with quantitative chemical experiments, which initiated the period of quantitative chemistry and made chemistry develop along the right track. /kloc-At the beginning of the 9th century, British chemist Dalton put forward modern atomism, emphasizing that the atomic mass of various elements is its most basic feature, and the introduction of the concept of quantity is a big difference from ancient atomism. Modern atomism made the chemical knowledge and theory at that time reasonably explained and became a unified theory to explain chemical phenomena. Then, the Italian scientist Avo Gardero put forward the concept of molecule. Since atomic and molecular theories were used to study chemistry, chemistry has really been established as a science. During this period, many basic laws of chemistry were established. Russian chemist Mendeleev discovered the periodic law of elements, while German chemists Justus von Liebig and Willer developed the theory of organic structure, which made chemistry a systematic science and laid the foundation for the development of modern chemistry.
/kloc-In the second half of the 9th century, after introducing physical theories such as thermodynamics into chemistry, not only the concepts of chemical equilibrium and reaction rate were clearly defined, but also the direction and conditions of substance transformation in chemical reactions could be quantitatively judged. The theoretical foundations of solution theory, ionization theory, electrochemistry and chemical kinetics have been established one after another. The birth of physical chemistry raised chemistry to a new level in theory. Through the analysis of minerals, many new elements have been found, and with the experimental verification of atomic and molecular theory, the classical chemical analysis method has its own system. The synthesis of oxalic acid and urea, the emergence of the concept of valence, the establishment of the six-ring structure of benzene and the tetrahedron of carbon valence bond, the resolution of tartaric acid into optical isomers, and the discovery of molecular asymmetry have led to the establishment of the theory of organic chemical structure, deepened people's understanding of molecular essence and laid the foundation of organic chemistry.
Modern Times
Chemistry in the 20th century is a science based on experiments. Experiment and theory have always been interdependent and mutually promoting aspects in chemical research. After entering the 20th century, influenced by the development of other disciplines of natural science, the theories, techniques and methods of contemporary science have been widely used. Chemistry has made great progress in understanding the composition, structure, synthesis and testing of substances, and has made many important achievements in theory. On the basis of inorganic chemistry, analytical chemistry, organic chemistry and physical chemistry, a new branch of chemistry has emerged.
The application of modern physical theory and technology, mathematical methods and computer technology in chemistry has greatly promoted the development of modern chemistry. At the end of 0/9, the discovery of electrons, X-rays and radioactivity created conditions for the great progress of chemistry in the 20th century.
In structural chemistry, the modern nucleated atom model established by the discovery of electrons not only enriches and deepens the understanding of the periodic table of elements, but also develops the molecular theory. Applying quantum mechanics to study molecular structure.
From the study of the molecular structure of hydrogen, the nature of chemical bonds was gradually revealed, and valence bond theory, molecular orbital theory and coordination field theory were established successively. The theory of chemical reaction also goes deep into the microscopic field. Using X-ray as a new analytical method to study the structure of matter can provide insight into the crystal chemical structure of matter. There are three methods to determine the chemical three-dimensional structure: X-ray diffraction, electron diffraction and neutron diffraction. Among them, the application of X-ray diffraction method has accumulated the most accurate information of molecular three-dimensional structure.
Spectral methods for studying the structure of matter have also been extended from visible spectrum, ultraviolet spectrum and infrared spectrum to nuclear magnetic resonance spectrum, electron selective resonance spectrum, photoelectron spectrum, ray resonance spectrum and Mossbauer spectrum. Combined with computer, a large number of materials related to material structure and performance have been accumulated, which are developing from experience to theory. With the increasing magnification of electron microscope, people can directly observe the structure of molecules.
Due to the discovery of radioactivity, the classical theory of elements has undergone profound changes. From the establishment of radioactive decay theory, the discovery of isotopes to the realization of artificial nuclear reaction and nuclear fission, the discovery of deuterium, neutrons, positrons and other basic particles, not only human understanding goes deep into the subatomic level, but also the corresponding experimental methods and theories are established; It not only realized the ancient alchemists' idea of changing elements, but also changed people's world outlook.
As a symbol of the 20th century, mankind began to master and use nuclear energy. Radiochemistry and nuclear chemistry appeared one after another and developed rapidly. Interdisciplinary disciplines such as isotope geology and isotope cosmochemistry have been born one after another. The periodic table of elements has been extended to 109, and overweight elements are being explored to verify the "stable island hypothesis" of elements. The theory of element origin, which depends on modern cosmology, and nuclide dating, which is closely related to evolution, are constantly supplementing and updating the concept of elements.
The synthesis of phenolic resin opens up the field of polymer science. With the synthesis of polyamide fiber in 1930s, the concept of polymer has been widely recognized. Later, the synthesis, structure and properties research and application of polymers constantly cooperated and promoted each other, which made polymer chemistry develop rapidly.
The synthesis and application of various polymer materials provide various important materials with excellent performance and low cost for modern industry and agriculture, transportation, medical and health care, military technology and people's daily necessities, and become an important symbol of modern material civilization. Polymer industry has developed into an important pillar of chemical industry. The 20th century is the golden age of organic synthesis. Great progress has been made in chemical separation methods and structural analysis methods. The structural problems of many natural organic compounds have been satisfactorily solved, and many new important organic reactions and specific organic reagents have been discovered. On this basis, fine organic synthesis, especially asymmetric synthesis, has made great progress.
On the one hand, various organic compounds with special structures and properties were synthesized. On the other hand, the basic substances of life, from unstable free radicals to bioactive protein and nucleic acids, were synthesized. Organic chemists have also synthesized natural organic compounds with complex structures and drugs with special effects. These achievements have greatly promoted the development of science; It provides favorable conditions for the synthesis of substances with high biological activity and the cooperation with other disciplines to solve the synthesis problems of biological substances and the chemical problems of prebiotics.
Since the 20th century, the development trend of chemistry can be summarized as: from macro to micro, from qualitative to quantitative, from stable to metastable, from experience to theory, and then used to guide design and pioneering research. On the one hand, provide as many new substances and materials as possible for the production and technical departments; On the other hand, in the process of mutual infiltration with other natural sciences, new disciplines are constantly emerging and developing in the direction of exploring life sciences and the origin of the universe.