catalogue
Basic information
Element description
Preparation and application of fluorine
Use of fluorine
Main characteristics and uses
isotope
It is found that hydrofluoric acid group is an element.
French physicist Ampere
Strive for the discovery right of fluorine
Experimental device designed by Knox brothers
Enlightenment of fluorine separation, Professor Freimut, Dr. Gore.
The fluorine element which is difficult to control is separated.
Movasan successfully separated fluorine for the first time in the laboratory.
trait
chemical property
Recommended daily intake of fluorine and health
food source
Need crowd
deficiency disease
Overexpression
efficacy
Chemical knowledge of fluorine with chemical properties
Valence of fluorine
How to get the basic information of fluoride from food?
Element description
Preparation and application of fluorine
Use of fluorine
Main characteristics and uses
isotope
It is found that hydrofluoric acid group is an element.
French physicist Ampere
Strive for the discovery right of fluorine
Experimental device designed by Knox brothers
Enlightenment of fluorine separation, Professor Freimut, Dr. Gore.
The fluorine element which is difficult to control is separated.
Movasan successfully separated fluorine for the first time in the laboratory.
trait
chemical property
Fluorine and health
It is suggested that the daily food intake should be based on the chemical properties of human deficiency and reality.
How does the chemical knowledge of fluorine absorb fluorine from food? Edit the basic information in this paragraph.
Element name: fluorine.
Pinyin: fú element symbol: relative atomic mass of element F: 18.998 403 2 Element type: nonmetal CASNo. 7782-4 1-4 EINECSNo。 23 1-954-8 atomic volume: (cm3/mol) 12.6 density: (kg: 15 16(85K, liquid),1.696 (273.
Chemical bond energy: (kj/mol) f-f159f-o190f-n272c-f484 standard heat of formation standard Gibbs free energy 0.0kJ/mol standard entropy 202.7 J/K*mol ionization energy (kj/mol) m-m+65438.
M2+-M3+6050 m3+-M4+8408 M4+-M5+ 1 1023 M5+-M6+ 15 164 M6+-M7+ 17867 M7+-M8+99。
α = 90 β = 90 γ = 90 Thermal conductivity: w/(m k) 27.7 Discovered by H.Moissan Date of discovery: 1886. Discovery process: 1886. The Frenchman Movasan made a U-shaped tube out of platinum.
Edit this paragraph element description
It belongs to halogen, a nonmetallic element with negative valence in compounds. Under normal circumstances, fluorine gas is a yellowish green, strong combustion-supporting and irritating poison gas, and it is one of the strongest oxidants known, with the element symbol F. Fluorine gas is a light yellow gas with a density of 1.696g/L (273. 15K, 0℃), a melting point of -2 19.62℃ and a boiling point of-188.1. It can react violently with most nonmetallic elements and metal elements to generate fluoride and burn it. It is extremely corrosive and toxic, so it should be handled with special care, and its liquid or vapor should not contact skin and eyes.
Preparation and use of editing this paragraph
Preparation of fluorine
Because of the strong oxidation of fluorine, aqueous electrolyte can't be used when producing fluorine. (The generated fluorine will immediately oxidize H2O and replace the oxygen in the water. Industrial method: electrolytic mixture of liquid anhydrous hydrogen fluoride (boiling point 20℃) and potassium hydrogen fluoride. When using anhydrous hydrogen fluoride as electrolyte to prepare fluorine, the anode fluorine yield is 2f = F2+2e, and the cathode hydrogen yield is 2hf2+2e = H2+4f. Laboratory method: lead sodium hexafluoride was heated to generate lead sodium tetrafluoride and fluorine gas. Chemical equation: NaPbF6=NaPbF4+F2. Condition: heating.
Use of fluorine
Elemental uses: Liquid fluorine can be used as oxidant for rocket fuel. Fluorine-containing plastics and fluorine-containing rubber have excellent properties. Polymers such as fluorine-containing plastics and fluorine-containing rubber have excellent properties, and are used for fluorine-oxygen blowing pipes and manufacturing various fluorides. Auxiliary data of elements: It was after repeated analysis by chemists at the beginning of19th century that the composition of hydrochloric acid was confirmed and chlorine was determined as an element, while fluorine was quickly confirmed as an element because it was similar to chlorine, and accordingly it existed in hydrofluoric acid. Although its element state was delayed to the 1980s of 19. Like chlorine, fluorine is one of the elements widely distributed in nature. Among halogens, its content in the earth's crust is second only to chlorine. As early as the first half of16th century, fluorite (CaF2 _ 2), a natural compound of fluorine, was described in the works of European mineralogists. At that time, this kind of ore was used as a flux and added to the molten ore to lower its melting point. So the Latin name of fluorine comes from fluo. The element symbol is thus determined as F. lavoisier regards hydrofluoric acid group as an element in the chemical element list 1789. At 18 10, David determined that chlorine is an element. In the same year, French scientist Ampere boldly inferred that there was a new element in hydrofluoric acid based on the similar properties and components of hydrofluoric acid and hydrochloric acid. He also suggested that the element fluorine be named after chlorine. However, elemental fluorine was not produced by Movasan, a student of French chemist Fremut, until June 26th, 886. 65438-0906 Movasan won the Nobel Prize in Chemistry. He is the second person who won the Nobel Prize in chemistry for discovering the contribution of chemical elements. It is meaningful to compare the discovery history of chlorine and fluorine. It was not until more than 30 years later that chlorine was separated that chlorine was considered as an element. However, fluorine was considered as an element before it was separated into elemental states. This historical fact shows that in the process of understanding objective things, people can understand them more quickly and clearly after gradually mastering some of their laws.
The main nature and purpose of editing this paragraph.
The melting point is -2 19.6℃, the boiling point is-188. 1℃, and the density is 1.696 g/L(0℃). Pale yellow gas is the most active nonmetallic element. Fluorinated reagents and fluxes used in metal smelting. PS: fluorine, atomic number 9, atomic weight 18.94032, the element name comes from the English name of its main mineral fluorite. 18 12 French scientist ampere pointed out that hydrofluoric acid contains a new element, but free fluorine has never been prepared. It was not until 1886 that French chemist Mu Wasang dissolved potassium fluoride in anhydrous hydrofluoric acid and electrolyzed it to produce elemental fluorine. Because fluorine is very active, there is no free fluorine in nature. The content of fluorine in the crust is 0.072%, and the important minerals are fluorite and calcium fluorophosphate. The natural isotope of fluorine is only fluorine 19. Fluorine is the most active and oxidizing substance, which can combine with almost all elements. Fluorine can react violently with all metals and nonmetals except noble metals such as inert gas, nitrogen, oxygen, chlorine, platinum, gold, etc. at room temperature, and it can also react violently with all organics except perfluoroorganics. When heated, fluorine can react violently with all metals, including inert metals such as gold and platinum, with all nonmetals except helium, neon, nitrogen and oxygen, and also with krypton and oxygen under special conditions. Fluorine ion is small in volume and easy to form stable coordination compounds with many positive ions; Fluorine reacts rapidly with hydrocarbons and is difficult to control. Fluorine reacts with NaOH: 2NaOH+2F2=2NaF+H2O+OF2, and fluorine reacts with water: 2H2O+2F2 =4HF+O2. Fluorine is the first element in halogen family, but it was discovered at the latest. From 177 1 year when Swedish chemist Scheler made hydrofluoric acid to 1886 when French chemist Movado separated elemental fluorine, it took more than 100 years. During this period, many people, such as David, Gay-Lussac and Knox brothers, were poisoned by the production of elemental fluorine, and Runje and Nikolai died of deep poisoning. Movasan summed up the experience and lessons of predecessors. He thinks that fluorine is very active and can't be electrolyzed, and the electrolyzed fluorine can be combined with substances as soon as it comes into contact with them. If low temperature electrolysis is adopted, it may be a solution to the problem. After many experiments,1On June 26th, 886, Movado, France finally prepared free fluorine by electrolyzing the mixture of potassium hydrogen fluoride and anhydrous hydrogen fluoride at low temperature, and won the Nobel Prize in chemistry.
Edit this isotope
Fluorine (atomic mass unit: 18.94032 (5)) * * has 18 isotopes, only one of which is stable, and fluorine-18 is a good positron. Changes of nuclear spin relative abundance in the half-life of neutron mass (U) of symbolic proton
excited energy
14F 9 5 14.03506(43)#？ 2-#
15F 9 6 15.0 180 1( 14)4 10(60)E-24s[ 1.0(2)MeV]( 1/2+)
16F 9 7 16.0 1 1466(9) 1 1(6)E-2 1s[40(20)keV]0-
17F 9 8 17.00209524(27)64.49( 16)S5/2+
1 8F9918.0009380 (6)109.771(20) minimum1
19f91018.4322 (7) stable 1/2+ 1.0000?
20F 9 1 1 19.99998 132(8) 1 1. 163(8)S2+
2 1F 9 12 20.9999490( 19)4. 158(20)s 5/2+
22F 9 13 22.002999( 13)4.23(4)S4+，(3+)
23F 9 14 23.00357(9)2.23( 14)s(3/2，5/2)+
24f9 1 5 24.00812 (8) 400 (50) ms (1,2,3)+
25f916 25.01210 (1) 50 (6) ms (5/2+)#
26F 9 17 26.0 1962( 18)9.6(8)ms 1
27F 9 18 27.02676(40) 4.9(2) millisecond 5/2+#
28F 9 19 28.03567(55)# & lt； 40 ns？
29F 9 20 29.04326(62)# 2.6(3)ms 5/2+#
30F 9 2 1 30.05250(64)# & lt； 260 ns？
3 1F 9 22 3 1.06043(64)# 1 # ms[& gt； 260ns] 5/2+#
Remarks: The data marked with # indicates that it has not been proved by experiments, and it is only theoretical speculation. The data in brackets represent data uncertainty.
Edit this paragraph to find out the answer.
The stock of fluorine in the crust is 0.072%, the Clark value is 0.0625, and the rank number of the existing quantity is 12. Fluorite mainly exists in nature, and its main components are calcium fluoride (CaF2) and cryolite (3NaF). AlF3) and calcium fluorophosphate [Ca5F(PO4)3].
Hydrofluoric acid group is an element.
Because the composition of hydrochloric acid has been completely determined, people have made a comprehensive study on the properties of hydrochloric acid group (chlorine). 1774, Swedish chemist Scheler c w (1742 ~1786, discoverer of chlorine) decomposed fluorite with sulfuric acid and found that a gas similar to hydrochloric acid gas (HCl) was released, and the acid obtained by dissolving in water was similar to hydrochloric acid. Then replace sulfuric acid and fluorite with nitric acid, hydrochloric acid and phosphoric acid. During the period, it was found that silicon compound deposits appeared in the instrument, which he thought was released by the interaction between a new acid and water. This is obviously a misunderstanding. According to the present chemical explanation, silicon compound is the residue of hydrofluoric acid rotten glass. French chemist lavoisier (A.L., 1743~ 1794) thinks that this new acid contains oxygen like hydrochloric acid (19 century ago chemists thought that all acids contain oxygen, so the oxygen element is also called acid element). He proposed that it was composed of an unknown compound of acid group and oxygen 1784. 1794, lavoisier was guillotined, because he was a minor official of Louis XVI's government, and was characterized as an accomplice of the tyrant by the masses of the French Revolution, ending his research career. After lavoisier's death, the French chemist Gai. Gay-Lussac (1778~ 1850) and others continued to study the purification of hydrofluoric acid. By 18 19, although anhydrous hydrofluoric acid has not been separated, the essence of this acid to glass and silicate has been clarified. casio 3+6hf→caf 2+si F4+3H2O； SiO2 + 4 HF → SiF4 + 2H2O
French physicist Ampere
/kloc-At the beginning of the 9th century, the chemical analysis technology has made rapid progress. At that time, the famous British chemist David (H. Davy, 1778~ 1829) received a letter from French Ampere (A.J.Ampere, 1775~ 1836). This letter (1865438+August 25, 2002) pointed out that there is an unknown chemical element in hydrofluoric acid, just like chlorine in hydrochloric acid, and it is suggested to name it "fluor", which comes from Latin and French and originally means "flowing, fluere".
Strive for the discovery right of fluorine
Ampere's suggestion was quickly recognized by European chemists. At this time, no one seems to doubt its existence, but no one really sees its true face. After 70 years, the separation of fluorine became the most tragic page in the history of chemical element discovery. In the second year after receiving the letter from Ampere, that is, in 18 13, David used his killer battery to electrolyze fuming hydrofluoric acid in an attempt to obtain elemental fluorine. At first, he found that hydrofluoric acid not only strongly corrodes glass, but also corrodes silver, so he made an electrolytic device with platinum (Pt) and amphibole (main component AgCl). At the beginning of the experiment, the anode produced a kind of. Later, he used fluorite as a container for hydrofluoric acid for electrolysis. As a result, the anode generates oxygen (O2) instead of fluorine (F2), which means that water in the acid is electrolyzed instead of hydrofluoric acid. At this time, chemists realized that water was one of the reasons for the success of the intervention. David's efforts not only ended in failure, but also he was forced to stop his research because of severe fluorosis because he didn't understand the harm of fluorine compounds to human body at that time. Lussac and others were poisoned by inhaling excessive hydrogen fluoride (HF) and withdrew from the stage of fluorine competition.
Experimental device designed by Knox brothers
1836 Two Scots, George Knox and Thomas, are members of the Irish Academy of Sciences. The Thomas Knox brothers made exquisite utensils out of fluorite. They put mercury fluoride in it and treated it with chlorine when heating. After a period of experiment, mercury chloride crystals were produced in the reactor, but at the same time, they found that the gold foil placed in the receiver above the vessel was corroded. In order to study the causes of gold foil corrosion, they put the gold foil in a glass bottle and injected concentrated sulfuric acid. As a result, the glass was corroded again, which undoubtedly transferred fluorine to the gold foil. It seems that the mercury chloride in the mixed product can be explained as the decomposition of mercury fluoride to produce fluorine and corrode gold. During the experiment, they accumulated hydrogen fluoride poisoning, Thomas was badly hit by fluorosis, and George was sent to Italy to recuperate for nearly three years before gradually recovering. Later, the Belgian chemist Runje (Louyet P., 18 18~ 1850) was not determined to continue their experiment because of the injury of the Knox brothers. Although he carried out the experiment step by step, he suffered from fluorosis for a long time.
Enlightenment of fluorine separation, Professor Freimut, Dr. Gore.
Freimut (e.1814 ~1894, left), curator of the French Museum of Natural History, decomposes calcium fluoride (CaF2), silver fluoride (AgF) and potassium fluoride (KF) with current, and the cathode produces metallic calcium respectively. However, because the electrolysis temperature is too high, when it appears, it immediately combines with the surrounding substances (such as electrodes and utensils) to form stable compounds, which insulates the electrodes, hinders electrolysis, and finally prevents the collection of anode substances. After that, he electrolyzed anhydrous hydrogen fluoride, but without success. Later, he proved that similar to the Knox brothers' method of treating fluoride with chlorine gas, only oxyfluoride (OF2) was obtained, not fluorine, due to the influence of experimental conditions. At this time, chemists feel that fluorine seems to be too active, and any substance will be corroded when it comes into contact with it. Freimut thought that this element seemed inseparable, and these hopeless experimental schemes were shelved. 1869, British chemist Dr. George Gore (1826~ 1908) electrolyzed hydrogen fluoride, which may have produced a small amount. However, it explodes with the hydrogen produced by the cathode. In order to improve the performance of the electrode, he used carbon, platinum, palladium and gold, but it was still corroded by the substances released by the anode. In his experimental report, he pointed out that the electrolysis temperature must be lowered to weaken the activity of fluorine, and the separation was successful. 17 years later, Mu Wasang, a student from Freimut, was born in June 1886.
The fluorine element which is difficult to control is separated.
Movasan was born in Paris on September 28th, 852. His father is an employee of the Oriental Railway Company, and his mother does some needlework to support his family. Movasan suffered from poverty when he was young. Although he was interested in learning and received more than five years of primary education, he was forced to drop out of school because of family embarrassment. 1870 Apprentice in a pharmacy called Brandry in Paris. 1872 is taught part-time by two professors, Fremi and Heron from Taiwan Province. His talent was noticed by Tai's family and persuaded to engage in chemical research. At the age of 27, he obtained the certificate of senior pharmacist, published a paper on chromium oxide the following year, and obtained a doctorate in physics. 188 1 Worked as an experimental assistant at the Paris Institute of Pharmacy, and engaged in the research project of extracting fluorine under the guidance of chemistry professor Freimut. Mohs summed up the reasons why the predecessors failed to separate fluorine, and based on their experimental scheme, in order to reduce the electrolysis temperature, he used phosphorus trifluoride and arsenic trifluoride with low melting point for electrolysis. A few bubbles appeared on the anode, but they still corroded the platinum electrode, and most of the bubbles were absorbed by liquid arsenic fluoride before rising to the liquid, so the separation failed again, and four poisoning incidents occurred, forcing the experiment to stop.
Movasan successfully separated fluorine for the first time in the laboratory.
1886 He summed up his teacher's failure experience in electrolyzing hydrogen fluoride. He used liquid hydrogen fluoride (HF, melting point -83℃) as electrolyte, and added potassium hydrogen fluoride (KHF2) to this nonconductive substance to make it a conductor. He used a platinum U-shaped tube to hold electrolyte, platinum-iridium alloy as electrode material, fluorite as nozzle cock, and shellac coated at the joint. The electrolytic cell (platinum U-tube) uses gaseous chloroethane (C2H5Cl) as the condenser. During the experiment, the temperature of the electrolyzer will drop to -23℃, and the experiment will start on June 26th, and the anode will release gas. When he passed gas through the silicon, the furnace ignited and gave off dazzling light. According to his report, the concentrated gas was yellow-green, and fluorine was finally separated successfully. Later, Mohs proved that fluorine can combine with most elements except a few inert gases. Later, he cooperated with Dewar to liquefy fluorine at a low temperature of-185℃. In such a low temperature environment, although fluorine no longer corrodes glass, it still has obvious effects on hydrocarbons and hydrogen, and fluorine is the most active element. Mo's achievements in discovering fluorine earned him the La Katz Award and the David Medal awarded by the Royal Society of Science. 1903 The German Chemical Society awarded him the Hoffman Medal; 1906 won the nobel prize in chemistry. He died on February 20, 1907 at the age of 54 due to long-term exposure to carbon monoxide and fluorine-containing toxic gases. His only son, Louis. Movasan died on the battlefield of the First World War.
Edit the special properties of this paragraph
Halogen elements have some similar properties, but F has some special properties because its atomic radius is particularly small. Special properties of 1 Main oxidation number: f no positive oxidation number 2. Dissociation energy: f-f br > I 5 .. thermodynamic stability of halides: fluoride is the most stable. 6. Halide coordination number (C.N.): fluoride is the largest. Some special properties of Asf3Asb3AsF5 Ascl5 (decomposed at -50℃) PbF4 PbCl4 (decomposed at room temperature) 2 .f can be explained from the following aspects: 1. F is the most electronegative. 2.φ? (X2/X-) F2/F- maximum; 3. the atomic radius r of f is the smallest; * * * Valence bonding compound p∏- p ∏ or p∏-d ∏ exists, and F-F bond energy is small. 4. Thermodynamic ionic halide: lattice energy U of fluoride is the largest. 5.* * * Valence halide: fluoride δδf GmO is the most negative. δ rhm = s+1/2d+I+(-e)+(-u) f has low dissociation energy, the largest lattice capacity of NaF, more negative enthalpy of formation and strong thermodynamic stability. Note: Hydrogen fluoride (hydrofluoric acid) is the only acid that can dissolve silicon dioxide and generate water-soluble fluorosilicic acid.
Edit the chemical properties of this paragraph.
Fluorine can react with water to generate hydrofluoric acid, which is weakly acidic but extremely corrosive.
Edit this paragraph fluorine and health
In order to prevent dental caries, fluoride began to appear in drinking water, toothpaste and various foods and beverages. To scientists' surprise, fluoride soon showed two sides: fewer patients with dental caries and more patients with dental fluorosis. What other effects fluoride has on human body has become a new problem that scientists must face. Dental fluorosis is just a warning to people of fluorosis. Even more frightening is that long-term intake of high-dose fluoride may lead to cancer, nervous system diseases and endocrine system dysfunction! Therefore, experts remind that the dosage of fluoride toothpaste must be small, generally not more than 1 g at a time, and toothpaste can account for one-fifth to one-quarter of the toothbrush head, so there is no need to squeeze the toothbrush head. Because children are not skilled in using toothbrushes, they may eat fluoride toothpaste by mistake, which is harmful to their health. Therefore, experts advise children not to use fluoride toothpaste. For many years, the whole people have been using high fluoride toothpaste, and almost all toothpastes take fluoride as the selling point of toothpaste. Popularizing fluoride toothpaste will increase tooth hardness and prevent dental caries. This is seriously wrong. For example, Northeast China, Inner Mongolia, Ningxia, Shaanxi, Shanxi, Gansu, Hebei, Shandong, Guizhou and Fujian. They are all high fluorine areas, and such areas are not suitable for using fluoride toothpaste. Fluorine is one of the important trace elements in human body, and fluoride is widely distributed in nature in the form of fluoride ions. Most fluoride in human body exists in bones and teeth, and fluoride is closely related to human life activities and metabolism of teeth and bone tissue. Fluorine is an indispensable component of teeth and bones. A small amount of fluoride can promote enamel to resist bacterial acid corrosion and prevent dental caries. Therefore, water treatment plants generally add a small amount of fluorine to tap water and drinking water. According to statistics, in areas with high fluoride intake, the osteoporosis rate and the incidence of dental caries in the elderly will decrease. There has always been a saying that drinking fluoride water for a long time will cause cancer. At present, this statement has been denied by the National Cancer Society of the United States, and everyone can rest assured.
Recommended daily intake
The recommended daily intake has not been determined. Most people drink water treated with fluorine, from which they can get 1 ~ 2 mg of fluorine every day. & gt& gt Human body's demand for fluorine
food source
Cod, salmon, sardines and other seafood, tea, apples, milk, eggs, fluoride-treated drinking water, etc.
Need crowd
The elderly lose a lot of bone calcium (calcium supplement products, calcium supplement information) and are prone to osteoporosis. Pay attention to fluoride intake is good for your health; Teens' enamel is still very fragile. They like sweets, so they are prone to dental caries. It is necessary to supplement fluoride.
deficiency disease
Dental caries, osteoporosis, slow bone growth, increased bone density and brittleness are the main manifestations of fluoride deficiency, which may also cause infertility or anemia.
Overexpression
Fluorosis: mainly manifested as skeletal fluorosis and dental fluorosis. Dental fluorosis: tooth deformity, softening, loss of luster, yellow enamel; Skeletal fluorosis: the bones become thicker and softer, osteoporosis, and easy to fracture. Chronic cough, lumbago and leg pain, osteoporosis, calcification of tendons and ligaments, hypertrophy of joints (joint products and joint information), hyperosteogeny, joint deformation and so on often occur in the later stage of fluorosis. In addition, some enzyme systems needed in the metabolic process of the body will also be destroyed, leading to multiple organ diseases.
efficacy
● Prevent dental caries ● Strengthen bones and prevent osteoporosis.
Edit the chemical properties of this paragraph.
Chemical knowledge of fluorine
Fluorine gas is the strongest oxidant known. Almost all organic and inorganic substances can react with fluorine except the highest valence metal fluoride and a few pure perfluoroorganic compounds. Even perfluorinated organic compounds can burn in fluorine atmosphere if they are contaminated by combustible substances. The compound of hydrogen and fluorine is extremely violent and reacts to generate hydrogen fluoride. Generally speaking, oxygen does not react with fluorine. However, there are two known oxyfluoride, namely OF2 and O2F2. Compounds formed by halogen itself include ClF, ClF3, BrF3 and IF5. As mentioned above, the reaction of carbon or most hydrocarbons with excess fluorine will produce carbon tetrafluoride and a small amount of tetrafluoroethylene or hexafluoropropane. Generally speaking, nitrogen is inert to fluorine and can be used as a diluent gas for gas phase reactions. Fluorine can also replace other halogens in many halogen-containing compounds. Most organic compounds will explode when they react with fluorine.
Valence of fluorine
The valence of fluorine is generally-1, but it is zero when it exists as a simple substance (but it is difficult for F to combine with H2 violently in the dark at room temperature). At present, fluorine has not been found to have a positive valence. Fluorine ions in fluoride are all-1 valence, and generally cannot be oxidized into elemental fluorine. However, it is known that dioxin difluoride can oxidize a small amount of fluoride such as boron trifluoride and phosphorus pentafluoride at low temperature. 2O2F2+2PF5 → 2[O2+]PF6+F2 In this reaction, the valence of oxygen is+1 before the reaction and +0.5 after the reaction, and the valence of fluorine is-1 before the reaction, and part of it rises to 0 after the reaction, resulting in fluorine gas. The reaction entropy increases obviously, pushing the reaction to the right. "Positive valence" fluorine has not been prepared, such as fluoperchloric acid FOClO3 (it should be called "perfluoroperchloric acid"), fluoronitrate FONO2 and fluorosulfonic acid FSO3F. The experimental results show that the oxidation state of fluorine is-1, and the oxidation state of oxygen connected with fluorine is 0. However, it should be noted that although these substances are prone to electrophilic addition and electrophilic substitution reactions of organic compounds, most of the products do not follow Marconi's law, but some literatures think that this is a free radical addition (substitution) reaction.
Edit this paragraph on how to get fluoride from food.
[2] About 25% of fluoride intake every day comes from food. All foods, including plant or animal foods, contain a certain amount of fluorine, but there are great differences. Plant food, such as grain seeds, vegetables, fruits, seasonings, etc. The fluorine content varies greatly due to different regions. For example, the fluorine content of Indian tea is higher than that of China, while the fluorine content of tea in northern China is lower than that in southern China. The fluorine content of rice in the south is also higher than that in the north. In animal food, the fluorine content of cartilage and tendon is high, and its dry products contain 45 ~ 880 mg/kg of fluorine, followed by epidermis. The fluorine content is 10 ~ 100 mg/kg. The fluorine content of glands with vigorous metabolism and secretion function is the least, about 1 mg. The average fluorine content of marine plants is about 4.5 mg/kg. Among the flavoring agents, the fluorine content of sea salt is the highest, generally 17 ~ 46 mg/kg, and the refined salt is 12 ~ 2 1 mg/kg.
Tisch
In our life, we will have many friends, but few can really talk to each other. But they accompanied us through our youth. What is a friend? Many peo