Of material composition, structure and nature of its transformation of subjects
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No. 2
Refers to celluloid. Such as: This comb is a chemical.
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No. 3
① research material composition, structure, properties and changes of the science disciplines is the basis of one of the natural sciences. ② celluloid known: This comb is ~ of.
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The basic concepts of chemistry
Chemistry (chemistry) is the study of the composition of the material, structure, properties, and changes of science. The term "chemical", if one explanation is that "changing science" from the literal meaning. Basic sciences like physics chemistry are the natural sciences. Many chemical is called the "central science" (Central science), because the chemical is a core part of scientific disciplines, such as materials science, nanotechnology, biochemistry. We recognize and use of chemical substances has an important role in the world is composed of matter, chemistry is one of the main methods and means for humans to understand and transform the material world, it is a historic yet vibrant discipline , its relationship to human progress and social development very closely, its achievement is an important symbol of social civilization. From the beginning of the use of fire primitive society, to use a variety of synthetic materials in modern society, human beings are enjoying chemistry results. Human life can continue to enhance and improve the contribution of chemistry in which plays an important role. Chemistry is one of the important basic science in physics, biology, physical geography, astronomy and other disciplines of mutual penetration, has been rapid development, but also promoted the development of other disciplines and technologies. For example, nucleic acid chemistry research to make today's biology increased from the cellular level to the molecular level, the establishment of molecular biology; chemical composition of the Earth, the Moon and other celestial bodies in the analysis, the distribution of the elements of the law, found the interstellar space there is a simple compound of celestial evolution and modern cosmology provides experimental data, but also enriched the content of dialectics of nature! Chemistry is an experimental basis in science.
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Chemical sprout
In ancient times, primitive humans in order to survive in the natural world to fight all kinds of disasters, the discovery and use of fire. Hominid from the beginning when the fire from barbarism to civilization, but also began using chemical methods to understand and transform the natural substances. Combustion is a chemical phenomenon. (Discovery and use of fire to improve the conditions of human existence, and to mankind wiser and stronger.) Mastered fire after humans began eating cooked food; then mankind has gradually found some changes in substance, as found in emerald green malachite and other copper ore above the burning charcoal, red copper will be generated. Thus, humans gradually learn and use of these substances change process, were prepared for human use value of the product. Humans gradually learned pottery, smelting; and later learned the brewing, dyeing and so on. These natural substances adapted from processed products, become a symbol of ancient civilizations. On the basis of these production practices on the germination of the ancient knowledge of chemistry. The ancients had some properties of substances according to the classification of the substance, and attempted to trace its primitive and its variation. 4th century BC or earlier, China put forward the theory of yin and yang that everything is composed of metal, wood, water, fire, earth made of five basic substances, and the five elements are formed by the interaction of yin and yang . This argument is simple materialist view of nature, with the "yin and yang" concept to explain the nature and substance of two opposing forces of mutual growth and decline that the interaction between the two is the root of all natural phenomena change. This saying is one of the theoretical basis of Chinese alchemy. 4th century BC, the Greek theory of five elements are also presented with a similar fire, wind, earth, water, said the four elements and ancient atomism. These simple elements of thought, namely the structure of matter and its changes budding theory. Later, the alchemy in China, to the 2nd century BC, the Qin and Han times, quite prevalent in alchemy, roughly in the 7th century spread to the Arab countries, and the integration of ancient Greek philosophy formed the Arab alchemy, alchemy in the Arab Incoming medieval Europe, the formation of European alchemy, the gradual evolution of modern chemistry. Guiding ideology of alchemy is convinced that the material can be transformed in an attempt alchemy furnace bullion or synthetic practice elixir. They have various types of material with the purpose clinkering experiment was conducted. To do this involves a change in substance use research vessels of various types, such as sublimation, a distiller, mortar, etc., but also created a variety of experimental methods, such as grinding, mixing, dissolving, clean burning, melting, sublimation and sealing . At the same time, a further classification of the properties of various materials, in particular the performance of each reaction. These are produced in modern chemistry laid the foundation for many instruments and methods after the improvements, still in use in today's chemical experiments. Alchemists invention of gunpowder during the experiment and found that a number of elements, made some alloys, also prepared a number of compounds and purification of these results we still use.
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ZTE chemistry
The 16th century, European industrial production booming, promote the creation and development of medicinal chemistry and metallurgical chemistry, alchemy turning life and make practical application, and then pay more attention to the chemical changes of matter itself. After the establishment of the elements of scientific concepts through sophisticated experimental study of combustion phenomena, the establishment of a scientific theory and the law of mass conservation oxidation, and subsequently established the law of definite proportions, the amount of times more than the law and the law of the compounds for further development of science chemistry foundation. Early 19th century, the foundations of the modern atomic theory, highlighted the quality of atoms of various elements of its basic characteristics, which introduced the concept of the amount, is a major difference with the ancient atomism. Modern chemical atomism make knowledge and theory at the time was a reasonable explanation, become unified description of theoretical chemistry phenomena. Molecular hypotheses put forward to establish the atomic and molecular theory, laid the foundation for the study of the structure of matter. After Mendeleev discovered the periodic law, not only the initial formation of inorganic chemistry system, and together form a system of chemical theory and atomic and molecular theory. Through the analysis of the mineral, discovered many new elements, combined with the experimental verification of the theory of atoms and molecules, classical chemical analysis methods also have their own system. Oxalic acid and urea synthesis, valence concept generation, six-ring structure of benzene and carbon valence bond theory, such as the creation of the tetrahedron, tartaric split into optical isomers, and molecular asymmetry, etc. discovery, leading to organic establishment of the theory of chemical structure, make people more in-depth understanding of the molecular nature, and laid the foundation for organic chemistry. After the 19 th century, theory of thermodynamics in physics into chemistry, not only to clarify the concept of chemical equilibrium and reaction rates, and can quantitatively determine the direction of chemical reactions and conditions of substance transformation. Have established a theoretical basis for the solution theory, ionization theory, electrochemistry and chemical kinetics. Birth of physical chemistry, the chemical increased from theory to a new level. Chemistry of the twentieth century is an established on an experimental basis in science, experimental and theoretical chemistry research has been interdependent, both with each other promotion. After the 20th century, due to the influence of other disciplines of natural sciences development and widespread application of contemporary scientific theories, techniques and methods, understanding the chemical composition of the material in the structure, synthesis, and testing aspects have a considerable progress, And in theory achieved many important results. In inorganic chemistry, analytical chemistry to produce a new branch of basic chemistry, organic chemistry and physical chemistry of the four branches of the. Theories of modern physics and technology, mathematics and computer technology applications in chemistry, played an important role in promoting the development of modern chemistry. 19th century, electronic, X-rays and radioactive chemical found significant progress in the 20th century created the conditions. Structural chemistry, since the beginning of electronic discovery and modern nuclear atomic model established, not only enrich and deepen the understanding of the periodic table, and the development of the molecular theory. Molecular structure of quantum mechanics, quantum chemistry produced. Hydrogen molecular structure from the beginning, and gradually reveals the nature of the chemical bond, has created the valence bond theory, molecular orbital theory and Pei field theory. With the deepening of the chemical reaction theory to the micro level. Application of X-ray analysis as a new method to study the structure of matter, chemical insight into the crystal structure of the material. Chemical determination of three-dimensional structure of the diffraction, X-ray diffraction, electron diffraction and neutron diffraction methods. Precise three-dimensional structure of the molecule to which the application of X-ray diffraction method accumulated the most information. Genealogy also studied the structure of matter from the visible spectrum, UV, IR extended to nuclear magnetic resonance spectroscopy, electron-demand resonance spectroscopy, photoelectron spectroscopy, radiation resonance spectroscopy, Mossbauer spectroscopy, and the computer associated with the accumulation a lot of material structure and performance-related information, is being developed by experience to theory. Electron microscope magnification continues to improve, people with direct observation of molecular structure. Because radioactive elements in the classic doctrine of discovery and profound change. From the creation of the theory of radioactive decay, isotopes found to artificial nuclear fission reactions and realize the discovery of deuterium, neutrons and positrons discovery and other elementary particles, not only human knowledge deep into the subatomic level, and the creation of appropriate experimental methods and theory; not only realized the ancient alchemists idea of changing elements, but also changed people's view of the universe. As a sign of the times in the 20th century, humans began to grasp and use of nuclear energy. Branches radiochemistry and nuclear chemistry have produced, and the rapid development; isotope geology, chemistry and other interdisciplinary isotope universe was born one after another. Expanded the periodic table, element number 109 in there, and is exploring the superheavy element to validate element "island of stability hypothesis." Modern cosmology and interdependent elements relative to the origin and evolution of doctrine and doctrine closely related radionuclide dating, etc., are constantly added and updated concept elements. In the theory of chemical reactions, molecular structure and chemical bonding due to increased awareness, the classic response to further deepen the theoretical statistics, in the transition state theory to build gradually to develop micro-response theory with microscopic molecular orbital theory reaction mechanism, and gradually establish a law of conservation of orbital symmetry and frontier orbital theory. Application of molecular beam, laser and plasma technology, making the detection of unstable chemical species and study to become a reality, so it has been possible from classical chemical kinetics, the macroscopic to microscopic dynamics depth statistics kinetics of single molecules or atomic level school. Development of computer technology, the molecules, quantum chemical calculations of the electronic structure and chemical reactions, chemical statistics, chemical pattern recognition, and large-scale processing and comprehensive surgical techniques, etc., have been considerable progress, some have gradually entered the chemical Education being. Research on catalysis to various models and theories proposed, into the organic catalysis and catalytic Monk from inorganic catalysis, starting from the angle of eukaryotic molecular microstructure and physical size of the angle of organic chemistry, and to study the role of enzymes The relationship between structure and function of enzymes. Analytical methods and tools are the basic methods and means of chemical research. On the one hand, the classic ingredients and composition analysis continues to improve, from the constant development of analytical sensitivity to trace, ultra trace, trace; on the other hand, many of the early development of new analytical methods, can penetrate to the structural analysis, conformational determination , isotope, a variety of direct determination of reactive intermediates such as free radicals, ionic, carbene, nitrene, prayer cards, etc., as well as the detection of short-lived metastable molecules and so on. Separation technology innovation, ion exchange, membrane technology, chromatography, and the like. Synthesis of various substances, chemical research is one of the purposes. Inorganic synthesis, the first synthetic ammonia. Not only created a synthetic inorganic ammonia synthesis industry, and led to the catalytic chemistry, the development of chemical thermodynamics and kinetics. Later, after another synthetic ruby, synthetic crystal, boron-hydrogen compounds, diamond, semiconductors, superconducting materials and ferrocene ligands and other compounds. Under the impetus of electronic technology, nuclear industry, aerospace technology and other modern industrial technology, a variety of ultra-pure materials, novel compounds and materials needed for the production of special techniques have been greatly developed. Successful synthesis of rare gas compounds ED chemists presented new challenges, the need to re-study of the chemical properties of zero to group elements. Inorganic chemistry and organic chemistry, biochemistry, physical chemistry and other subjects of mutual penetration of produce organometallic chemistry, bioinorganic chemistry, inorganic chemistry, solid emerging disciplines. Synthetic phenolic resin, opened up the field of polymer science. Polyamide synthetic fibers in the 1930s, so the concept of polymer is widely recognized. Later, the synthesis, structure and properties of polymers, three applications to maintain and promote co-ordination, the polymer chemistry to develop rapidly. Various polymer materials synthesis and applications of modern industry and agriculture, transportation, health care, military technology, as well as all aspects of people's basic needs, offers a variety of excellent performance and lower cost of important materials, has become an important symbol of modern material civilization . Polymer industry is an important pillar of the development of the chemical industry. The 20th century was the golden age of organic synthesis. Separation means the chemical and structural analysis methods have made significant progress, many of the structural problems of natural organic compounds have been satisfactorily resolved, also found many new important organic reactions and specific organic reagents, on this basis, fine organic synthesis, in particular made great progress in asymmetric synthesis. On the one hand, the synthesis of various structures and special properties are special organic compounds; other synthesized from radicals has an unstable protein, nucleic acids and other biologically active substances based life. Organic chemists have also synthesized complex structure of natural organic compounds and have effects of the drug. These achievements in promoting the development of science has played a huge role; for the synthesis of highly biologically active substances, and cooperative solutions to the synthesis of living matter and solve problems with other disciplinary problems before the chemical substance of life, to provide favorable conditions. Since the 20th century, the development trend of the chemical can be summarized as follows: there is a macro to micro, qualitative to quantitative, stable state to the metastable state of development, gradually increased from experience to theory, and then used to guide the design of research and open innovation. On the one hand, for the production and technical departments to provide as much new material, new material; the other hand, with the other natural sciences in the process of mutual penetration of continuous generation of new disciplines, and to explore the direction of the origin of the universe and life sciences development.
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The role of chemistry
A chemical plays an important role in ensuring the survival of mankind and to continuously improve the quality of human life aspects. Such as: the use of chemical fertilizers and pesticides production in order to increase food production; using chemical synthetic drugs to inhibit bacteria and viruses, safeguard human health; using chemical development of new energy, new materials to improve the human condition; using chemical naturally integrated application resources and protect the environment in order to make human life better. 2 Chemistry is a practical discipline, and mathematical physics and other disciplines that form the basis of a common rapid development of natural science. Core knowledge of chemistry has been used in various areas of natural science, chemistry is to create and transform the nature of the power of an important pillar. Currently, the use of chemical house to observe and chemical point of thinking about social problems, and use of chemical knowledge to analyze and solve social problems, such as energy, food issues, environmental issues, health issues, resources and sustainable development issues. 3. Chemistry and other disciplines intersect with penetration, resulting in a lot of edge disciplines such as biochemistry, geochemistry, cosmic chemistry, marine chemistry, atmospheric chemistry, and so on, making biotechnology, electronics, aerospace, laser, geology, marine science and technology, etc. rapid development. Today, chemical increasingly penetrated into all aspects of life, especially the major issues of human and social development are closely related. In short, chemistry and human clothing, food, housing, transportation and energy, information, materials, national defense, environmental protection, medicine and health, resource utilization, and other aspects are closely linked, it is a practical discipline a pressing social need.
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Subject classification chemistry
Chemistry in the development process, according to the means of molecular classes and research studies, for different purposes, tasks, and derive different levels of many branches. Before the 1920s, the chemical traditionally divided into inorganic chemistry, organic chemistry, physical chemistry and analytical chemistry of the four branches. After the 1920s, due to the rapid development of world economy, the birth of the electronic bond theory and quantum mechanics, the rise of chemical research and computer technology, electronic technology in theory and experimental technologies have gained new tools, resulting from this discipline rapid development since the 1930s, there has been a new look. Now the chemical content is generally divided into biochemistry, organic chemistry, polymer chemistry, applied chemistry and chemical engineering, physical chemistry, inorganic chemistry, a total of 80 top-five, actually includes seven branches. According to the development of today's chemistry and the circumstances it with astronomy, physics, mathematics, biology, medicine, earth science and other subjects of mutual penetration of the chemical can be classified as follows: Inorganic Chemistry: Elements of chemistry, inorganic synthetic chemistry, inorganic chemistry, inorganic solids chemistry, coordination chemistry (ie, complex chemistry), isotope chemistry, bioinorganic chemistry, organometallic chemistry, metal enzyme chemistry Organic Chemistry: general chemistry, organic synthetic chemistry, metallic and non-metallic organic chemistry, physical chemistry, bio-chemistry, organic analytical chemistry. Physical chemistry: chemical structure, thermal chemistry, chemical thermodynamics, chemical kinetics, electrochemistry, solution theory, fluid interface chemistry, quantum chemistry, catalysis and theory. Analytical chemistry: chemical analysis, instruments and new technology analysis. Polymer Chemistry: Natural polymer chemistry, synthetic polymer chemistry, polymer chemistry, polymer applications, polymer material. Nuclear Chemistry: radioactive chemical, radiation chemistry, radiation chemistry, isotope chemistry, nuclear chemistry. Biochemistry: general biochemistry, enzymes, microbial chemistry, plant chemistry, immunochemistry, fermentation and biological engineering, food chemistry. Other chemical-related interdisciplinary include: geochemistry, marine chemistry, atmospheric chemistry, environmental chemistry, cosmic chemistry, interstellar chemistry.
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化学诺贝尔奖得主
1963 K. Ziegler (German), G. Natta (Italian) found the use of new catalysts for polymerization method, and basic research in this field
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Chemical Education
China's chemical education from junior high school, high school became one of science, in addition to two compulsory textbooks, and "Chemistry and Life", "Chemistry and Technology", "material structure and properties", "chemical reaction principle", "Organic Chemistry basis "," chemistry experiment "six elective courses. Green Chemistry Green chemistry, also known as "environmentally benign chemistry", "environmentally friendly chemistry", "cleaning chemicals" green chemistry in recent years has generated and developed, is a "new chemical baby." It involves organic synthesis, catalysis, biochemistry, analytical chemistry and other disciplines, extensive content. Green chemistry is the most important feature in the beginning of the prevention of pollution on the use of scientific methods, and thus the process and end are zero or zero pollution emissions. Many countries have already "green chemistry" as one of the main directions of progress in the new century chemistry. One of the core content of green chemistry is the "atom economy", that take full advantage of the various atoms in the reactants and thus can fully utilize resources, but also to prevent contamination. The concept of atom economy in 1991 the famous American chemist Trost (for which he was awarded the Presidential Green Chemistry Challenge Award in the 1998 academic awards) proposed utilization of reaction measured by atomic atom economy for efficient Organic Synthesis should maximize the use of raw materials every atom molecule, making it binding to the target molecule, to achieve zero emissions. Green organic synthesis should be of atom economy. Atom utilization is higher, the reaction produces less waste, pollution of the environment caused by the less. The core content of the two green chemistry, its meaning is mainly reflected in the five "R" on: first, Reduction eleven "reduction" that reduce the "three wastes" emissions; Second Reuse - "re-use", such as PROCESS catalyst carrier, etc. This is to reduce the costs and the need to reduce waste; third Recycling - "Recovery", can effectively achieve the "resource saving, less pollution, less cost" requirement; fourth Regeneration - "Regeneration", that turning waste into treasure, save resources, energy, effective way to reduce pollution; fifth Rejection - "Say No" means no substitute for some, they can not be recovered, recycled and reused, significant toxic side effects and pollution of raw materials, refused to use in the chemical process, which is the most fundamental way to prevent contamination. Definition of green chemistry is to use technology, principles and methods to eliminate chemical on human health, safety and the environment of toxic and hazardous chemicals, therefore, also known as environmentally friendly chemical or chemical clean. In fact, green chemistry is not a new science. Green chemistry not only have major social, environmental and economic benefits, but also illustrate the negative effects of the chemical can be avoided, revealing a people's initiative. Green chemistry reflects the linkages and interactions of chemical science, technology and society is highly developed chemical sciences and the social role of chemical products for the scientific development of the chemical itself is an arrival of a new phase. As the new century generation, not only have the ability to develop new, more environmentally friendly chemicals to prevent chemical contamination; And let the younger generation to understand green chemistry, green chemistry accepted for green chemistry and make due contributions. Talking Fun memory chemical knowledge Fun things can cause interest, leading to nervous excitement, sparking motivation to create the best memories mental state, easy to remember and can be securely maintained. Therefore, in the teaching and learning process, we should put some knowledge of chemistry dull taste of difficult to remember as much as possible. If compile verses, use homonym, metaphor and other methods that can help memory. First, verses mnemonics Verses mnemonics to remember that for the use of chemical knowledge compiled phonology, financial knowledge and interest in one, read fluently, Lee Kee easy to chant. If the liquid poured from the small jar to tube operation verses: "three-finger grip palm to label leaching pipeline relative to the line of sight down.", "Three-finger grip" refers to the thumb when holding test tubes, index finger, middle finger grip tubes; " sight down "refers to observe the amount of liquid pouring liquid inside the tube to prevent the dumping of excess. Another example is the oxidation of ammonia nitrate can be programmed as follows legal verses: "heating the catalytic oxidation of ammonia, a nitrogen ammoniated water heating; re-oxidation of nitric oxide, nitrogen dioxide brown; nitrogen dioxide dissolved in water, nitric acid to the system came out." Like element symbols, valence, solubility table and so can be compiled verses to memory. Verses in the teaching and learning process can indeed be used to help memory, so you relaxed and happy to consolidate learning outcomes. Second, the homophonic memory Homophonic mnemonics to remember is to take the chemical content of everyday life combined homonym for garbage. As the percentage content of the crust of the first three elements of the "oxygen, silicon, aluminum," North harmonic tones to be "raised girl." Again, the metal activity order: potassium, calcium, sodium, magnesium, aluminum, manganese, zinc, iron; tin, lead, copper, mercury, silver, platinum, gold can homonym for: "add a beautiful new tin Lead altogether a hundred pounds. " Third, knowing mnemonics Knowing memory method is to put some abstract concept of self-understanding and re-processing, and then go to Memorize. Experimental manipulations such as hydrogen or carbon monoxide reduction of copper oxide is: when the start of the experiment, after the first heating ventilation, end of the experiment, the first stop after stop heating ventilation, thus knowing denoted as "spare gas, kerosene lamp late and leave early." Another example is the reaction of the four basic types are knowing as "one divides into many" (decomposition reaction) "together more than one" (combination reaction), "replaced" (displacement reaction), "mutual exchange" (metathesis). Fourth, Associative Memory Associative memory is to put some chemical experiments or conceptual approach to memory with Lenovo. Association method is a method with verification of memory, is the product of old and new knowledge to establish contact. In the process of teaching chemistry characteristics should seize the issue, from here the development of the association. As memories of hydrogen, carbon, carbon monoxide reduction of copper oxide experiment available experimental Lenovo, Lenovo contrast, another example of elemental and compound will put together the two concepts of memory: "the pure substance the same (different) kinds of elements called elemental ( compound). For the text less difficult to remember but messy little problem peculiar to seize key words carried Lenovo, such as sodium hydroxide uses are: for the soap, oil, paper, textile, printing and dyeing industry, can be written as: "paper (weave) on dyed Feiyou." V. concentrated mnemonics Concentrated mnemonic is for a class of chemical knowledge or rule based on a deep understanding, you can _select_ a representative abbreviated word or phrase into the broad outline of the skeleton must be memories. Seven Steps laboratory experiments such as oxygen system denoted;. "Inspection, installation, clip, points, closing, moving, put out", "check" means checking device tightness; "loaded" refers to a test tube fitted drugs; " Folder "refers to the tube clip in formwork stage;" point "refers to ignite the alcohol lamp;" revenue "refers to the collection of gas;" shift "refers to the first out of the water conduit;" put out "refers to extinguish an alcohol lamp. Another example is filtering operation concentrated attention points as: "a, two low, three against." Six guessing mnemonics Puzzle Memory law is full of some chemical knowledge compiled informative, interesting, vivid and humorous riddle for garbage. Such as carbon monoxide nature riddles memory is: "May children bend the left, to the right circle on children, the meniscus can be warm, full moon energy combustion, toxic, colorless, taste, restore and combustible." Seven metaphor mnemonics Metaphor vivid memory method is by means of metaphor, to visualize the concepts difficult to remember, to remember with a visual image. If the arrangement is extranuclear law: "the opportunity of low energy electrons is usually closer to a place away from the nucleus appears much chance of high energy electrons is usually a place far away from the nucleus appears much." This problem is more abstract, not all of a sudden you can understand. If we play like this parable can be understood, but also easy to remember it. Compared to the nucleus of the earth, the high capacity of geese, eagles and other birds compared to high energy electrons, the low capacity of sparrows and other birds swallow compared with low energy electrons. High ability of birds often fly sky high from the ground, often in low capacity bird low ground where activities. Another example of the olefin double bond in organic chemistry, and prone to polymerization of the addition reaction to produce polyvinyl polymerization reaction, can use the image of the hand _insert_ion Yin "C = C" and the hand in hand "-C-C-" analogy, so easier to remember Zhu short, fun memories in many ways, such as icons memory, induction memories, song lyrics by memory and so on. In the process of teaching and learning according to the actual situation, summed up in his memory suitable method. Just remember that fast, I remember accurate, remember the prison, it may be a good memory method. [] Periodic Table Periodic Table is a specific form of periodicity in tabular expression, which reflects the internal structure of the atomic elements and rules of interlinkages between them. Referred to the periodic table periodic table. There are many forms of expression of the periodic table, the most commonly used is the long-form periodic table Werner. There are seven cycles of the periodic table, there are 16 races and four zones. Element in the periodic table to reflect the structure of the atomic element. In the same row of the periodic table of elements constituting a cycle. Electronic layers of elements with atomic cycle is equal to the ordinal number of the cycle. Elements in the same vertical line (Section Ⅷ family includes three vertical lines) called "family." Family is inside the outer shell of atomic configurations reflected. E.g., the outer electron configuration, IA family is ns1, IIIA family is ns2 np1, O family is ns2 np4, IIIB family is (n-1) d1 · ns2 like. Periodic Table can vividly periodicity. Graded according to the law of the periodic table can be speculated that the atomic structure and properties of elements and their compounds of various elements. That year, according to the nature of the Mendeleev periodic table of elements around the unknown elements and compounds, after a comprehensive speculated that successfully predicted the nature of the unknown elements and their compounds. Now scientists use the periodic table, looking for guidance preparation semiconductors, catalysts, chemical pesticides, new material elements and compounds. The periodicity of modern science is 1869 Russian scientist Dmitri Ivanovich Mendeleev (Dmitri Ivanovich Mendeleev) finishing first, he will then known 63 elements in accordance with the table of atomic weights and sizes arranged in the form, the elements have similar chemical properties on the same line, is the prototype of the periodic table. Use of the periodic table, Mendeleev predicted characteristics of success had not yet discovered the elements (gallium, scandium and germanium). 1913 British scientists Merthyr 勒利 hit with a metal cathode ray generating X-rays and found that the larger the atomic number, X-ray, the higher the frequency, so he thinks positively charged nucleus determines the chemical properties of the elements, and the elements according to the nucleus positive charge (ie, the number of protons or atomic number) arrangement, after years of amendments before becoming a contemporary of the periodic table.
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Baidu chemistry right
Baidu chemistry it plays a leading role in the development of absolute chemical theory and practice, the chemical industry is an important network platform for discussion.
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化学在改善衣食住行所起的作用
With the long-kettle, the boiler wall layer of brownish sediment, where it comes from it? We know that water dissolve many inorganic salts such as calcium bicarbonate, magnesium bicarbonate, and a small amount of calcium sulfate, calcium chloride, the class of calcium, magnesium class. Heating, bicarbonate is easily decomposed to produce carbon dioxide and carbonate, carbon dioxide emitted into the air, insoluble in water calcium carbonate, magnesium carbonate is slightly soluble in water, so they could _set_tle down with a long-kettle, boiler, so With the scale. " "Scale" thermal conductivity is poor, with "scale" the kettle, boiler water heating will result in energy waste, factory boilers, the "scale" from Thick, automatic peeling part of the down, the various parts of uneven heating also cause an explosion. Want to remove the "scale" can be used very dilute hydrochloric acid and acetic acid wash, and then immediately drained of acid and washed with water.
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History of Chemistry
Very old history of chemistry, we can say from humans learned to use fire, began the earliest chemical practice. Our ancestors log fires, the use of fire, baked goods, cold nights heating, driven beast, take advantage of the phenomenon of combustion heat and light. It's just a time to accumulate experience. The formation of chemical knowledge, the development of chemistry through a long and winding road. It is accompanied by the development progress of human society, is the inevitable result of social development. And its development, and promote the development of productive forces and promote historical progress. Development of chemical, mainly through the following periods: (A) chemical infancy: From ancient times to 1500 BC, humans learned by the raging fire made out of clay pottery, metal from the ore is burned out, learn from grain brewing wine, linen and other fabrics dyed to, these are the practical experience After a long journey under the direct inspiration from the earliest chemical process, but has not yet formed chemical knowledge, but infancy chemistry. (B) the period of alchemy and medicinal chemistry: From about 1500 BC to AD 1650, is controlled by chemical alchemy, alchemy. To obtain the elixir of immortality, or a symbol of wealth in gold, alchemists and alchemists began the earliest chemical experiments, and then record sum alchemy books have also emerged. Although the alchemists, alchemists have ended in failure, but they are in the process of refining the elixir of life, exploring the "Midas touch" approach to achieve a mutual transformation between substance use artificial methods, and accumulated a lot of material conditions and chemical changes occurring phenomenon, for the development of chemistry has accumulated a wealth of practical experience. "Chemistry" was the word appears, its meaning is "alchemy." But with the decline of alchemy, alchemy, people see it more absurd side, turned to get the proper chemical methods play in medicine and metallurgy, development, outside of Pharmacology and Chemical Metallurgy become a Prepare a wealth of material science. (C) phlogiston chemistry periods: The period from 1650 to 1775, was conceived during the modern chemistry. With the accumulation of metallurgical industry and laboratory experience, people have come up perceptual knowledge, theoretical studies of chemical change, the chemical becomes a branch of natural science. This stage marks the beginning of a British chemist Robert Boyle Chemical elements specified scientific concepts. Followed by chemical and borrow phlogiston freed from alchemy. Phlogiston considered capable of burning fuel because it contains phlogistic, fuel combustion is discharged in phlogistic processes, although this theory is wrong, but the fact that the large number of chemical under a unified concept explains many chemical phenomena . In the phlogiston theory popular hundred years, chemists to explain the phenomenon, a lot of experiments and found that the presence of a variety of gases accumulated more new knowledge about the material transformation. In particular phlogiston theory holds that the chemical reaction is a process of mass transfer to another substance, conservation of matter in chemical reactions, these ideas laid the foundation of modern chemistry thinking. During this period, not only from the scientific practice, but also ideologically and made preparations for the development of modern chemistry, became pregnant during this period of modern chemistry. (D) quantitative chemical periods: The period from 1775 to 1900, was a period in the development of modern chemistry. After 1775 years ago, Lavoisier elaborated experiments with quantitative chemical oxidation combustion theory, pioneered the quantitative chemical periods, so that the development of the chemical on the right track. Early 19th century, the British chemist Dalton proposed the modern atomic theory, and then the Italian scientist Avogadro proposed molecular concepts. Since the atomic - molecular theory to study chemistry, chemistry really been established as a science. During this period, the establishment of a number of basic laws of chemistry. Russian chemist Dmitri Mendeleev discovered the periodic law, the German chemist Liebig and Wheeler developed the theory of organic structures, which are the chemical sciences to become a system, but also for the development of modern science foundation. (E) Scientific interpenetration periods: The period from the beginning of the 20th century, essentially, is a modern learning period. Early 20th century, the rapid development of physics, the emergence of various physical testing methods, promoting research solution theory, the structure of matter, catalysts and other areas, especially the development of quantum theory, the chemical and physics have more in common language, solve many of the outstanding issues on the chemistry, physical chemistry, structural chemistry theory gradually improved. Meanwhile, chemistry and geology, biology ED penetration, protein, enzymes difficult to solve structural problems in the past to get in-depth research, biochemistry rapid development. Indeed, the development of science is never enough, and thus the development of chemistry will never stagnant.
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物理百科
The historical development of chemistry
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English Expression
n.: chemistry, scientific study of the structure of substances, how they react when combined or in contact with one another, and how they behave under different conditions, chemical
biochemistry