1860, Mendeleev was deeply troubled by the lack of systematicness in inorganic chemistry when considering the writing plan of the book Principles of Chemistry. Therefore, he began to collect information about the nature of various known elements and related data, and collected all the achievements made by predecessors in practice. The long-term practice and cognitive activities of human beings on the issue of elements have provided him with rich materials. On the basis of studying predecessors' achievements, he found that some elements have similarities besides characteristics. For example, fluorine, chlorine, bromine and iodine of halogen elements are known to have similar properties; Alkali metal elements such as lithium, sodium and potassium are oxidized quickly in the air, so they can only exist in the form of compounds in nature. Some metals, such as copper, silver and gold, can be kept in the air for a long time without corrosion, which is why they are called precious metals.
So Mendeleev began to try to arrange these elements. He made a rectangular cardboard for each element. Element symbols, atomic weights, element properties and their compounds are written on each rectangular cardboard. Then nail them to the wall of the laboratory and arrange them repeatedly. After a series of queues, he discovered the regularity of chemical properties of elements.
Therefore, when someone regarded Mendeleev's discovery of the periodic law of elements as simple and easily said that he got this great discovery by playing poker, Mendeleev seriously replied that it took him about 20 years to publish the periodic law of elements in 1869. He picked out the chemical elements from the chaotic maze. In addition, because of his great courage and confidence, he was not afraid of famous critics, laughed at, practiced and publicized his own views, and finally he was widely recognized. In order to commemorate his achievements, people named the new element 10 1 discovered by American chemist Hipperg in 1955 as Mendeleev, that is, "holmium".
periodic law of elements
The periodic law of elements reveals a very important and interesting law: the properties of elements change periodically with the increase of atomic weight, but they are not simply repeated. According to this truth, Mendeleev not only corrected some wrong atomic weights, but also predicted the existence of more than 15 unknown elements. As a result, Mendeleev discovered three elements when he was still alive. 1875, French chemist Bois Baudrin discovered the first filled element, named gallium. All the properties of this element are the same as Mendeleev predicted, but the proportion is inconsistent. Mendeleev wrote a letter to the Paris Academy of Sciences, pointing out that the proportion of gallium should be around 5.9, not 4.7. At that time, the gallium was still in the hands of Boyce Baldwin, and Mendeleev had never seen it. This incident surprised Boise Baudrin, so he tried to purify and re-measure the proportion of gallium, and the result confirmed Mendeleev's prediction that the proportion was indeed 5.94. This result greatly improves people's understanding of the periodic law of elements, and also shows that many scientific theories are called truth, not when scientists create these theories, but when they are constantly confirmed by practice. When Mendeleev predicted new elements through the periodic table, some scientists said that he arrogantly invented some nonexistent elements. Through practice, Mendeleev's theory has been paid more and more attention.
Later, according to the theory of periodic law, people sorted out and classified more than 100 elements that had been discovered, and listed today's periodic table of chemical elements, which was posted on the laboratory wall and arranged at the back of the dictionary. It is a lesson that every student must learn and master when studying chemistry.
Now we know that in the vast universe of human life, all substances are composed of this 100 element, including ourselves.
However, what are chemical elements? Chemical elements are the general name of the same kind of atoms. So people often say that atoms are the "basic bricks" that make up the material world, which is still possible in a certain sense. But the periodic law of chemical elements shows that chemical elements do not exist in isolation and are not related to each other. These facts mean that elements and atoms must have their own internal laws. There has been a revolution in the theory of material structure.
At last, at the end of 19, there was a new development in practice and radioactive elements and electrons were discovered, which was originally an excellent opportunity to uncover the inside story of atoms. However, Mendeleev was puzzled in practice. On the one hand, he is afraid that these findings "will complicate things" and shake "the foundation of the whole world outlook"; On the other hand, I think this "will be a very interesting thing ... the reason for the periodic law may be revealed". But Mendeleev himself died in 1907 with this contradictory thought on the eve of uncovering the essence of periodic law.
Mendeleev didn't see it. It is precisely because of a series of great discoveries and practices at the end of 19 and the beginning of the 20th century that the essence of the periodic law of elements was revealed and the old idea that atoms were inseparable in Mendeleev's era was abandoned. While sublating its inaccurate part, it fully affirms its reasonable connotation and historical position. On this basis, the new theory of periodic law of elements is more practical than Mendeleev's theory.
Mendeleev's life
190765438+1October 27th, the cold wind in Petersburg, the capital of Russia, was bleak, the mercury column on the thermometer dropped to more than 20 degrees below zero, and lanterns covered with black gauze were lit everywhere in the street, showing a sad atmosphere. Tens of thousands of people marched slowly in the street. Walking at the front of the line is neither a wreath nor a portrait, but a big wooden sign held by more than a dozen young students, with many squares written on it, such as "C", "O", "Fe" and "Zn".
It turned out that the deceased was a famous Russian chemist Mendeleev, and the table with many squares on it was the periodic table of chemical elements-Mendeleev's main contribution to chemistry.
Mendeleev was born in a family of middle school principals with 17 children, and he ranked 14. Just a few months after his birth, his father suddenly went blind, and then he lost his position as principal. It is difficult to make a living on a small pension, so the whole family moved to a nearby village because my uncle runs a small glass factory there. The scene of workers melting and processing glass has a great influence on his future chemical research on beakers and flasks. 184 1 In the autumn of, Mendeleev, who was under seven years old, was admitted to the city middle school with his teenage brother, which caused a sensation in the local area. Misfortune is always accompanied by poor families. Mendeleev's father died at the age of 13, and the factory was burned to ashes at the age of 14. The mother had to move again, marry off her adult daughters and let her two sons work. /kloc-in the spring of 0/849, Mendeleev graduated from middle school, and the mother sold her property and was bent on letting her youngest son go to college. With the help of a friend of his father, Mendeleev entered the Physics Department of Petersburg Teachers College. After only one year, he became a top student. In addition to intense study, I also wrote a brief scientific review to get a small amount of manuscript fees. By this time, he had lost any financial support: his uncle and mother died one after another. 1854 graduated from university and won the college gold medal. He became an associate professor at the age of 23 and a professor at the age of 3 1.
It was "organic chemistry" that made him gain his initial fame. In order to write this book, he never left his desk for almost two months. After the age of 70, I broke down from overwork and my eyes were half blind. Work from early morning to 5: 30 pm every day, and continue to work late into the night after lunch. He died at his desk with a pen in his hand. 1869 The discovery of the periodic law of elements made him famous, and many foreign academies hired him as an honorary academician. Once, a reporter asked him how he came up with the periodic law. Mendeleev said with a smile, "I've been thinking about this question for 20 years. Do you think I'm just waiting for death, and suddenly I succeed?"
It is true that we should always remember Mendeleev's motto: "What is a genius? If you work hard for your life, you will become a genius! "
well-known saying
The seeds of science grow for the people's harvest.
A theory that has not been tested by practice, no matter how beautiful, will lose its weight and will not be recognized; Practice that is not based on weighty theory is doomed to failure.
Science can not only "give young people knowledge and happiness", but also make people accustomed to labor and the pursuit of truth, create real spiritual wealth and material wealth for the people, and create things that cannot be obtained without it.
To discover fruitful truth, a person needs millions of people to ruin their lives in failed exploration and tragic mistakes.
Genius is like this, work for life, and then become a genius!
The seeds of science grow for the people's harvest.
There is no double diligence, neither talent nor genius.
The exploration road of element period
The road to climb the peak of science is difficult and tortuous. Mendeleev also suffered a lot on this road. When he became an associate professor of chemistry, he was responsible for teaching the course "Fundamentals of Chemistry". How many elements are there in nature in theoretical chemistry? What are the similarities and differences between elements, and what are their internal relations? How should new elements be discovered? These problems were in the exploratory stage in the field of chemistry at that time. In the past 50 years, chemists all over the world have made tenacious efforts to open this secret door. Although some chemists, such as Debelina and Newlands, objectively described some relationships between elements from a certain depth and different angles, they failed to find the correct classification principle of elements because they did not summarize all elements as a whole. Mendeleev, a young scholar, also rushed into this field without fear and began a difficult exploration.
He studied day and night, exploring the chemical characteristics of elements and their general atomic characteristics, and then recorded each element on a small paper card. He tried to capture the commonness in the complex characteristics of elements. But his research failed again and again. But he didn't give in, didn't lose heart, and went on working.
In order to solve this problem completely, he went out of the laboratory and began to investigate and collect information. 1859, he went to Heidelberg, Germany for further scientific study. In the past two years, he devoted himself to studying physical chemistry, which made him more solid in exploring the internal relations between elements. 1862, he inspected Baku oil field, made an in-depth study of liquids, re-measured the atomic weights of some elements, and gained a deep understanding of the characteristics of elements. 1867, he took the opportunity of working in the Russian exhibition hall of the World Industrial Fair held in France, and visited many chemical plants and laboratories in France, Germany and Belgium, which broadened his horizons and enriched his knowledge. These practical activities not only increased his ability to understand nature, but also laid a solid foundation for him to discover the periodic law of elements.
Mendeleev returned to the laboratory and continued to study his paper card. He arranged the elements with re-determined atomic weights in order of their atomic weights. He found that elements with similar properties have different atomic weights; On the contrary, some elements with different properties have similar atomic weights. He firmly grasped the relationship between the atomic weight and properties of elements, and constantly studied them. His brain is often dizzy from excessive tension. However, his efforts were not in vain. 1February 869 19, he finally discovered the quality law. His periodic law shows that the properties of simple objects, as well as the forms and properties of elemental compounds, are periodically dependent on the atomic weight of elements. Mendeleev boldly pointed out that some recognized atomic weights at that time were inaccurate in the process of sorting out the element list. For example, the atomic weight of gold recognized at that time was 169.2. Accordingly, gold should be ranked before osmium and platinum in the element list, because their recognized atomic weights are 198.6 and 196.7 respectively, and Mendeleev firmly believes that gold should be ranked after these three elements, and the atomic weight should be re-determined. The retest results show that osmium is 190.9, platinum is 195.2 and gold is 197.2. Practice has proved the correctness of Mendeleev's assertion and periodic law.
There are still many gaps in Mendeleev's periodic table, which should be filled by undiscovered elements. Mendeleev theoretically calculated the most important properties of these undiscovered elements and concluded that they were between the properties of adjacent elements. For example, in the two spaces between zinc and arsenic, he predicted that the properties of these two unknown elements are like aluminum and like silicon. Just four years after his prediction, French chemist Boublanc discovered gallium from wurtzite by spectral analysis. Experiments show that the properties of gallium are very similar to that of aluminum, which is exactly what Mendeleev predicted. The discovery of gallium is of great significance, which fully shows that the periodic law of elements is an objective law of nature. It provides rules for studying elements, exploring new elements and looking for new materials in the future. The periodic law of elements exploded in the world like a heavy artillery!
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Mosele
Edit entry Mosele
Henry Gwyn Mosley.
British physicist. 1887165438+1was born in weymouth, Dorset on 23rd October; 1915 August 10 died in grybolu, Turkey.
Moselle's father, an anthropologist and professor of comparative anatomy, participated in the Challenger expedition for the first time as a naturalist. Moselle was only four years old when his father died. Young Moselle doesn't intend to engage in life science research in the future, but is interested in physics. He studied at Eton College and Oxford University (where he won scholarships). Later, he studied under the guidance of Rutherford. Among Rutherford's talented young assistants, he was the youngest and the cleverest.
After Laue and Prague proved that X-rays would be diffracted by crystals, Moselle used this technique to measure and compare the X-ray radiation wavelengths of various elements. This kind of radiation was discovered by Bakla several years ago.
In the above research, Moselle clearly confirmed Bakla's conjecture, that is, the wavelength of labeled X-rays decreased uniformly with the increase of atomic weight of emitting elements. Moselle attributed this rule to the fact that when the atomic weight increases, the number of electrons in the atom increases and the nucleus is positively charged. (It was later discovered that the nuclear charge reflects the number of positively charged protons in the nucleus. )
This discovery led to a major improvement in Mendeleev's periodic table. Mendeleev once arranged his periodic table of elements in the order of atomic weight, but in order to explain periodicity, this order was changed in two places in the table. Moselle proved that if the elements are arranged according to their nuclear charge number (that is, according to the number of protons in the nucleus, which is called atomic number from now on), there is no need to make such a change.
Furthermore, it is conceivable to insert some elements with different numbers between any two adjacent elements in Mendeleev's periodic table, because the minimum atomic weight difference between adjacent elements is irregular. However, if arranged by atomic number, the situation is very different. The atomic number must be an integer, so there can be no undiscovered new elements between iron with atomic number 26 and cobalt with atomic number 27. This also means that there are only 92 elements from the simplest element known at that time to the most complex element uranium. In addition, Moseler's X-ray technology can also determine the vacancies in the periodic table of elements that represent undiscovered elements. In fact, when Moselle realized the concept of atomic number in 19 14, there were still seven such vacancies. In addition, if someone claims to have found a new element to fill the vacancy, Moselle's X-ray technology can be used to check the authenticity of this report. For example, this method is used to verify the authenticity of two reports about lutetium in cities and hafnium in Hevesy.
In this respect, X-ray analysis is a new complex chemical analysis technology that emerged in the 20th century. Like the Heyrovsk, Jaroslav polarimeter, it uses a more accurate method to determine the light absorption performance and potential changes, rather than relying on the old weighing and titration methods.
In other words, although Moselle's work did not make significant changes to Mendeleev's periodic table, it completely fixed the positions of various elements in the periodic table.
At this time, when World War I broke out, Moselle immediately enlisted as a lieutenant in the Corps of Engineers. At that time, people didn't understand the importance of science to human society, so they thought there was no reason not to let Mo Ze Le go to war like millions of other soldiers. Rutherford tried to send mozer to do scientific work, but failed. 19 15 15 On June 3rd, Moselle set sail for Turkey, and two months later, he was killed in Grybolu, for an insignificant and muddled battle. His death did not bring any benefits to Britain and the whole world (if he had to find it, he left his property to the Royal Society). Judging from his achievements (he was only 27 years old when he died), among the countless people who died in the war, his death caused the greatest loss to mankind.
If Moselle can survive, no matter how unpredictable the development of science is, he will surely win the Nobel Prize in Physics. Sigban inherited Moselle's research work and won the Nobel Prize.
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History of the Periodic Table of Chemical Elements
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