I am a senior three student, and the college entrance examination is coming soon. I'm also applying for chemistry. There are many answers online. I'll intercept some useful answers for you, which are within the outline.
Carbon and oxygen groups are not classified separately in the syllabus because they cover a large area: AL and Fe have separate chapters.
Brief introduction of carbon element
Carbon is a nonmetallic element, which is located in the second periodic group of the periodic table of elements.
Carbon is a very common element, which exists widely in the atmosphere and crust in various forms. The understanding and utilization of simple carbon has a long history, and a series of compounds of carbon-organic matter are the basis of life. Carbon is one of the components of pig iron, wrought iron and steel. Carbon can chemically combine with itself to form a large number of compounds, which is an important molecule in biology and commerce. Most molecules in organisms contain carbon [1].
Carbon compounds are generally obtained from fossil fuels, and then separated and further synthesized into various products needed for production and life, such as ethylene and plastics.
Carbon has various forms, such as crystal element carbon, such as diamond and graphite; There is amorphous carbon such as coal; There are complex organic compounds such as animals and plants; Carbonate, such as marble. The physical and chemical properties of elemental carbon depend on its crystal structure. High hardness diamond and soft graphite have different crystal structures, each with its own appearance, density and melting point.
The chemical properties of elemental carbon are relatively stable at room temperature and insoluble in water, dilute acid, dilute alkali and organic solvents. React with oxygen at different high temperatures to generate carbon dioxide or carbon monoxide; Among halogens, only fluorine can react directly with elemental carbon; Under heating, elemental carbon is easily oxidized by acid; At high temperature, carbon can also react with many metals to form metal carbides. Carbon is reducible and can be used to smelt metal at high temperature.
Chemical symbol: c
Number of protons: 6
Atomic number: 6
Period: 2
Family: IVA
Electron shell distribution: 2-4
Electronic configuration: 1 s222p 2
Oxidation value (oxide): 4,3,2 (weakly acidic)
Color and appearance: black (graphite), colorless (diamond)
State of matter: solid state
Melting point: about 3550℃ (diamond)
Boiling point: about 4827℃ (sublimation)
Mohs hardness: graphite 1-2, diamond 10.
Oxidation state: mainly -4,, C+2, C+4 (and other oxidation states).
Chemical bond energy: (kj/mol) c-h 411c-c348c = c 614c ≡ c839c = n 615c ≡ n891c =
Bonding: carbon atoms are generally tetravalent and need four single electrons, but its ground state has only two single electrons, so hybridization is always needed when bonding. The most common hybridization method is sp3 hybridization, which makes full use of four valence electrons, evenly distributed in four orbits, and belongs to isotropic hybridization. This structure is completely symmetrical, and it is a stable σ bond after bonding, and it is very stable without the repulsion of lone electron pairs. All the carbon atoms in the diamond are combined in this way. The carbon atoms of alkanes also belong to this category.
Pay attention to the electronic type of CO2 and its crystal type.
Note that diamond and graphite are the same element, but their internal structures are different.
Many organic substances are related to carbon! !
oxygen
Element attribute data
Element symbol: o
Relative atomic mass: 16
Oxidation state:
Main -2
Other-1, 0,+1, +2
Element description:
Normally colorless, odorless and tasteless gas. Density 1.429g/L, 1.4 19g/cm3 (liquid), 1.426g/cm3 (solid). Melting point -2 18.4℃, boiling point-182.962℃, liquefied into light blue liquid at-182.962℃, and solidified into snowy light blue at -2 18.4℃. The valence of solids is generally 0 and -2. The ionization energy is13,438+08 ev. All chemical elements can form compounds with oxygen except inert gas. Most elements can generate oxides when heated in an oxygen-containing atmosphere. Many elements can form more than one oxide. Oxygen molecules can form hydrated crystals O2. H2O and oxygen. H2O2 is unstable at low temperature. The solubility of oxygen in air is 4.89 ml/100 ml of water (0℃), which is the basis of life in water. The abundance of oxygen in the earth's crust ranks first. The dry air contains 20.946% oxygen by volume; Water consists of 88.8 1 wt% oxygen. Besides O 16, there are O 17 and O 18 isotopes.
Element source:
Oxygen can be produced by heating mercury oxide or decomposing nitrate in glass containers and the reaction between concentrated sulfuric acid and manganese dioxide. Oxygen is usually produced by heating potassium permanganate in the laboratory, or by heating the mixture of potassium chlorate and manganese dioxide. It is also convenient to use catalyst to catalyze the decomposition of hydrogen peroxide [1] to produce oxygen. Large-scale production of oxygen is realized by liquefaction and fractionation of air under the condition of low purity requirements, and a small amount of oxygen or high purity oxygen is produced by electrolytic water.
Element usage:
Oxygen is widely used in metallurgical processes, such as smelting, refining, welding, cutting and surface treatment. Liquid oxygen is the refrigerant and oxidant of high-energy fuel. Its mixture with sawdust and coal powder is called liquid oxygen explosive, which is a good explosive material. When oxygen is mixed with steam, it can be used instead of air to blow into the gas producer, and high calorific value gas can be obtained. Liquid oxygen can also be used as rocket propellant; Oxygen is the basic component of many biological processes, so oxygen has become one of the necessities that need to be loaded in large quantities to undertake any task in space. Oxygen therapy is used in medical treatment to treat anoxia such as pneumonia and gas poisoning. The exploitation, production and creation of stone and glass products need a lot of oxygen.
Element auxiliary data:
Oxygen is the main component of air. Many oxygen-containing compounds, such as potassium nitrate and mercury oxide, give off oxygen when heated. Oxygen is the most abundant element in the earth's crust. All these indicate that oxygen may have been obtained long ago. However, because oxygen exists as a gas under normal conditions, it is different from solid and liquid that can be contacted and seen, so people can't simply identify it by intuitive observation.
Since the16th century, in western Europe, many researchers have carried out preliminary scientific and chemical experiments on the gas obtained by heating oxygenated compounds and the role of air in material combustion and animal respiration, thus discovering oxygen. That is to say, after people correctly realized the burning phenomenon and discovered oxygen, they completely overturned the phlogiston theory.
Properties This product is a colorless gas; Odorless and tasteless; Strong combustion-supporting ability.
This product 1 can be dissolved in 7 times of ethanol or 32 times of water at 20℃ and atmospheric pressure.
Identification of this product can make red wood suddenly ignite and burn.
The chapter on oxygen in senior high school involves oxidation-reduction reaction, which can be done through the idea of conservation in the process of doing the problem.
This teacher can talk!
aluminium (Al)
A metallic element, symbol AI, silvery white, shiny, tough, light and malleable. Aluminum used in daily utensils is usually called steel fine or steel grade.
Element name: aluminum
Element symbol: Al
Element type: metal
Number of protons in the nucleus: 13
Number of electrons in the nucleus: 13
Nuclear power number: 13
Oxidation state: mainly Al+3.
Other Al0, Al+2
Period: 3
Number of families: IIIA
Molar mass: 27
Hydride: AlH3
Oxide: Al2O3
Chemical formula of the highest valence oxide: Al2O3
Element source: the most abundant metal in the earth's crust, more than 7%.
Element uses: It can be used as structural materials for airplanes, vehicles, ships, ships and rockets. Pure aluminum can be used as EHV cable. Aluminum used as daily utensils is usually called "steel essence" and "steel grade"
Industrial method: electrolytic melting of the mixture of alumina and cryolite.
Other compounds: AlCl3- aluminum chloride NaAlO2- sodium metaaluminate Al(OH)3- aluminum hydroxide.
Introduction: Blue silvery white trivalent metallic element, with good ductility, toughness and [loud] sound, is famous for its light weight, good electrical and thermal conductivity, high reflectivity and oxidation resistance.
source
Aluminum exists as a compound in various rocks or ores, such as feldspar, mica, Gaolingcheng, bauxite, alum and so on. Made of alumina and cryolite (Na3AlF6)*** by melting electrolysis.
Reaction proces of extracting aluminum from bauxite
① dissolution: bauxite is dissolved in NaOHaq.
Alumina +2 sodium hydroxide = 2 sodium aluminate +H2O
② Filtering: removing residual iron oxide, sodium aluminosilicate, etc.
③ Acidification: excessive CO2 is introduced into the filtrate.
NAA lo 2+CO2+2H2O = Al(OH)3↓+nah co 3
(4) filtering and burning aluminum hydroxide.
2Al(OH)3= Al2O3+3H2O (high temperature)
Note: In order to reduce the melting temperature of alumina during electrolysis, cryolite (Na3AlF6) is added to Al2O3.
⑤ electrolysis: 2Al2O3 (melting) = 4Al+3O2 ↑ (electrifying)
Note: The reason why AlCl3 is not melted by electrolysis is that AlCl3 is a valence compound and its molten state is not conductive.
use
Aluminum can replace metals in other oxides (aluminothermic method). Its alloy is light and tough, and it is a structural material for making airplanes, rockets and automobiles. Pure aluminum is widely used in cables. Widely used in making daily utensils.
Aluminum and its alloys
Pure aluminum is very soft, not tough, and has good ductility. It can be drawn into filaments and rolled into foil, and is widely used in manufacturing wires, cables, radio industries and packaging industries. Its conductivity is about two-thirds of that of copper, but its density is only one-third of that of copper. Therefore, compared with copper wire and aluminum wire with the same quality and length, the conductivity of aluminum is about twice as high as that of copper, and the price is lower. Therefore, high-voltage lines in the field are mostly made of aluminum, which saves a lot of costs and relieves the tension of copper materials.
The thermal conductivity of aluminum is three times that of iron. In industry, aluminum is often used to make various heat exchangers and heat dissipation materials, and many cookers used in families are also made of aluminum. Compared with iron, it is not easy to rust and prolongs the service life. Aluminum powder has silvery white luster and is often mixed with other substances as a coating, which is painted on the surface of iron products to protect iron products from corrosion and is beautiful. Because aluminum can emit dazzling white light and a lot of heat when burned in oxygen, it is often used to make some explosive mixtures, such as ammonium aluminum explosive.
In metallurgical industry, thermite is often used to melt refractory metals. For example, when aluminum powder and iron oxide powder are mixed together, they will react violently after being triggered, and are often used to weld railway tracks in traffic; Aluminum is often used as deoxidizer in steelmaking industry; Smooth aluminum plate has good reflective performance, and can be used to manufacture high-quality mirrors, condensing bowls, etc. Aluminum also has good sound absorption performance. According to this feature, some broadcast rooms and ceilings in modern buildings are made of aluminum. Pure aluminum is softer. 1906, German metallurgist Villm added a small amount of magnesium and copper to aluminum to make a tough aluminum alloy. Later, this patent was bought by the German Dura company, so aluminum is also called "Dura aluminum". In the development process of the next few decades, people developed a lot of aluminum alloys according to different needs, which played a very important role in many fields.
Adding a small amount of aluminum to some metals can greatly improve their properties. For example, bronze aluminum (containing 4% ~ 15% aluminum) has high-strength corrosion resistance, hardness close to that of low-carbon steel, and metallic luster that is not easy to blacken. It is often used in jewelry and construction industries, manufacturing machine parts and tools, pickling equipment and other equipment in contact with dilute sulfuric acid, hydrochloric acid and hydrofluoric acid. Making brushes and clamping handles for electric welding machines; Heavy gear and worm wheel, metal forming mold, machine tool guide rail, non-spark tool, non-magnetic chain, pressure vessel, heat exchanger, compressor blade, ship propeller and anchor, etc. Adding magnesium to aluminum produces aluminum-magnesium alloy, which is much harder than pure magnesium and aluminum, and retains the characteristics of light weight, and is often used to manufacture aircraft fuselage and rocket body; Make doors and windows to beautify the living environment; Build ships.
Aluminizing is one of the chemical heat treatment methods of steel. A high-temperature resistant alumina film is formed on the surface of ordinary carbon steel or cast iron to protect the iron inside. Aluminum is a very important metal, however, many aluminum-containing compounds are also very important to human beings.
Aluminum-containing compound
The content of aluminum in the earth's crust is higher than that of silicon and oxygen, ranking third, mainly existing in aluminosilicate ores, bauxite and cryolite. Alumina is a white amorphous powder with many variants, among which α-A 12O3 and β-Al2O3 are the most common. Corundum, which exists in nature, belongs to α-Al2O3. Its hardness is second only to that of diamond, with high melting point and acid and alkali resistance. It is usually used to make some bearings, abrasives and refractories. Such as corundum crucible, can withstand the high temperature of 1800℃. Corundum has many colors because it contains different impurities. For example, a trace of Cr(III) is red, which is called ruby; Sapphire containing Fe(II), Fe(III) or Ti(IV) is called sapphire.
β-A 12O3 is a porous substance with a surface area of several hundred square meters per gram. Also called activated alumina, it can adsorb many kinds of gas and liquid molecules such as water vapor, and is often used as adsorbent, catalyst carrier and desiccant. It is also used as raw material for industrial aluminum smelting.
Aluminum hydroxide can be used to prepare aluminum salts, adsorbents, mordants and ion exchangers, and can also be used as raw materials for porcelain glazes, refractories, fireproof fabrics and so on. Its glue solution and thousand glue are used as acidic drugs in medicine, which have the functions of neutralizing gastric acid and treating ulcers, and are used to treat gastric and duodenal ulcers and hyperacidity.
Sodium metaaluminate is often used in printing and dyeing fabrics, producing lake blue dye, making wool glass rot, soap and hardened building stone. In addition, it is also a good water softener, filler for papermaking, water purifier and polishing agent for rayon.
Aluminum trichloride is a commonly used catalyst in petroleum industry and organic synthesis. For example, the alkylation reaction of aromatic hydrocarbons, also known as Friedel-Crafts alkylation reaction, generates electrophilic substitution between aromatic hydrocarbons and halogenated hydrocarbons (or olefins and alcohols) under the catalysis of anhydrous aluminum trichloride, resulting in alkyl substituents of aromatic hydrocarbons. Aluminum chloride hexahydrate can be used to prepare deodorizers, safe disinfectants and petroleum refining.
Aluminum bromide is a common catalyst for organic synthesis and isomerization.
Aluminum phosphide will emit highly toxic phosphine gas when it is wet or acid, which can poison pests. It is used as a fumigant to kill pests in warehouse in agriculture.
Aluminum sulfate is often used as filler, mordant, water purifying agent and fire extinguishing agent, petroleum purifying agent and decoloring agent in papermaking, and is also used to make precipitated pigments, fireproof cloth and medicines.
Cryolite, namely sodium hexafluoroaluminate, is often used as an insecticide in agriculture; White opacifier used for making glass and enamel in silicate industry.
Alum extracted from alunite by heating is an important water purifying agent and mordant, which is used as an astringent in medicine. Aluminum nitrate can be used for tanning and making white thermoelectric wires, and can also be used as mordant. Aluminum silicate is often used to make pigments for glass, ceramics and paints, as well as fillers for paints, rubbers and plastics. Silica-alumina gel has hygroscopicity and is often used as a catalyst carrier for petroleum catalytic cracking or other organic synthesis.
In the carboxylate of aluminum; Aluminum dicarboxylate and aluminium triformate are commonly used as mordants, waterproofing agents and fungicides. Aluminum diacetate is not only used as mordant, but also used as sword collector and disinfectant, and also used in embalming solution for corpses. Aluminum triacetate is used to make waterproof and fireproof fabrics and lakes; Drugs (mouthwash, astringent, preservative, etc. ) and used as mordant. ; Aluminum octadecanoate (aluminum stearate) is often used as anti-precipitation agent for paint, waterproof agent for fabric, thickener for lubricating oil, antirust oil for tools, heat-resistant stabilizer for PVC plastics, etc. Aluminum oleate is not only used as a waterproof agent for fabrics and a thickener for lubricating oil, but also as a drier for paints and a lubricant for plastic products.
Sucralfate, also known as Weikuining, is an alkaline aluminum salt of sucrose sulfate. Can be combined with pepsin, directly inhibit proteolytic activity, and has a lasting effect. It can also form a protective film, which has a strong protective effect on gastric mucosa, helps mucosal regeneration and promotes ulcer healing, and has low toxicity. It is a good therapeutic agent for gastrointestinal ulcer.
In recent years, people have developed some new aluminum-containing compounds, such as alkyl aluminum. With the development of science, people will make better use of aluminum and its compounds for the benefit of mankind.
Related chemical equations of aluminum:
2AL+6HCL=2ALCL3+3H2↑
2AL+3H2SO4=AL2(SO4)3+3H2↑
2Al+2NaOH+2H2O=2NaAIO2+3H2↑
2Al(OH)3= (heated) Al2O3+H2O
Aluminum sulfate +6NH3. H2O=2Al(OH)3↓+3(NH4)2SO4
Al2O3+6HCl=2AlCl3+3H2O
Al2O3+2NaOH+3H2O=2Na[Al(OH)4]
AlCl3+3NaOH=Al(OH)3↓+3NaCl
Aluminum hydroxide+sodium hydroxide = sodium [aluminum hydroxide]
AlCl3+3NaOH=Al(OH)3↓+3NaCl
Al2(SO4)3+6 nah co 3 = 2 Al(OH)3↓+3 na2so 4+6 CO2
Naalo2+HCl (small amount) +H2O = Al (OH) 3 ↓+NaCl.
Aluminum hydroxide = aluminum trichloride+trihydrate.
Naalo2+4hcl (excess) = AlCl3+NaCl+2h2o.
2nalo2+CO2+3H2O = 2al (OH) 3 ↓+Na2CO3 Strong acid generates weak acid.
AL's words pay attention to his duality, that is, both acidity and alkalinity, as well as his ionization equation, preparation method and AlO2- salt.
Iron Fe
Chemical properties of iron
[One of the chemical properties of iron]
Iron Fe, atomic number 26, relative atomic mass 55.847. There are many allotropes of iron, such as α-iron, β-iron, γ-iron and б-iron. Iron is a relatively active metal, which ranks ahead of hydrogen in the metal activity sequence table. At normal temperature, iron is not easy to react with nonmetallic elements such as oxygen, sulfur and chlorine in dry air, but it reacts violently at high temperature. Iron burns in oxygen to generate Fe3O4, and hot iron reacts with water vapor to generate Fe3O4. Iron is easily dissolved in dilute inorganic acid and concentrated hydrochloric acid to form divalent iron salt and release hydrogen. When it meets concentrated sulfuric acid or concentrated nitric acid at room temperature, an oxide protective film is formed on the surface to "passivate" iron, so iron products can be used to contain concentrated sulfuric acid or concentrated nitric acid. Iron is a valence-changing element, and its common valence states are +2 and +3. When iron reacts with sulfur, copper sulfate solution, hydrochloric acid and dilute sulfuric acid, it loses two electrons and becomes +2 valence. It reacts with Cl2, Br2, nitric acid and hot concentrated sulfuric acid and is oxidized to Fe3+. Fe3O4 produced by the reaction of iron with oxygen or water vapor can be regarded as FeO Fe2O3, in which 1/3 of Fe is +2 and the other 2/3 is +3. The trivalent compounds of iron are relatively stable.
[The second chemical property of iron]
The electronic configuration of iron is (Ar)3d64s2, and its oxidation states are 0, +2, +3, +4, +5 and +6. Iron is a strong reducing agent with active chemical properties, which can slowly replace hydrogen in water at room temperature, and the reaction rate increases above 500℃.
3Fe+4H2O===Fe3O4+4H2↑
It is difficult for iron to react with oxygen in dry air, but it is easy to corrode in humid air, and the corrosion is faster if it contains acid gas or halogen vapor. Iron can reduce gold, platinum, silver, mercury, bismuth, tin, nickel or copper plasma from solution, for example:
Copper sulfate+iron = = ferrous sulfate+copper
Iron is dissolved in non-oxidizing acids such as hydrochloric acid and dilute sulfuric acid to form ferrous ions and release hydrogen; In cold dilute nitric acid, ferrous ions and ammonium nitrate are formed;
Fe+H2SO4===FeSO4+H2↑
4Fe+ 10 HNO 3 = = = 4Fe(NO3)2+nh4no 3+3H2O
Iron is dissolved in hot or concentrated nitric acid to produce iron nitrate and release nitrogen oxides. In concentrated nitric acid or cold concentrated sulfuric acid, the surface of iron will form an oxide film and be passivated. Iron reacts violently with chlorine when heated. Iron can also be directly combined with sulfur, phosphorus, silicon and carbon. Iron and nitrogen can not be directly combined, but react with ammonia to form iron nitride Fe2N.
The most important oxidation states of iron are +2 and +3. Ferrous ion is light green, and it is easy to be oxidized into trivalent iron ion in alkaline solution. With the increase of hydrolysis degree, the color of iron ions changed from orange to brown. Pure trivalent iron ions are lavender. Both divalent and trivalent iron are easy to form stable coordination compounds with inorganic or organic ligands, such as Phen, which is phenanthroline, and the coordination number is usually 6. Zero-valent iron can also form various carbonyl irons with carbon monoxide, such as Fe(CO)5, Fe2(CO)9, Fe3(CO) 12, etc. Iron carbonyl is volatile, and its vapor is highly toxic. Iron also has +4, +5 and +6 valence compounds, but only +6 valence compounds in aqueous solution.
There are two main types of compounds: ferrous (II) and ferric (III) compounds. Ferrous compounds include ferrous oxide, ferrous chloride, ferrous sulfate and ferrous hydroxide. Iron-containing compounds include iron oxide, ferric chloride, ferric sulfate and ferric hydroxide.
For example, in potassium ferrocyanide K4 [Fe (CN) 6] 3H2O (common name: yellow blood salt) and potassium ferricyanide K3[Fe(CN)6] (common name: red blood salt). Ferrocene is a compound of iron and cyclopentadiene, and it is a metal-organic compound with sandwich structure.
Three States of Chemical Properties of Iron
The electronic configuration of iron is (Ar)3d64s2, and its oxidation states are 0, +2, +3, +4, +5 and +6. Iron is a strong reducing agent with active chemical properties. It can slowly replace hydrogen in water at room temperature, and the reaction rate increases above 500℃: 3Fe+4H2O = = Fe3O4+4H2.
It is difficult for iron to react with oxygen in dry air, but it is easy to corrode in humid air, and the corrosion is faster if it contains acid gas or halogen vapor. Iron can reduce gold, platinum, silver, mercury, bismuth, tin, nickel or copper plasma from solution, such as CuSO4+Fe = = FeSO4+Cu.
Iron is dissolved in non-oxidizing acids such as hydrochloric acid and dilute sulfuric acid to form ferrous ions and release hydrogen; In cold dilute nitric acid, ferrous ions and ammonium nitrate are formed;
Fe+h2so 4 = = = feso 4+H2↑4Fe+ 10 HNO 3 = = = 4Fe(NO3)2+nh4no 3+3H2O
Element source
Iron is an abundant element in the earth's crust, second only to oxygen, silicon and aluminum. Magnetite, hematite, limonite and siderite are important iron ores. Monomer metals are usually made of coke, iron ore and Carboniferous stones. Pure iron can be obtained by reducing pure iron oxide with hydrogen. Iron with carbon content exceeding 1.7% is called pig iron (or cast iron). Iron melt with carbon content less than 0.2% is called wrought iron or wrought iron. Iron melt with carbon content between 1.7-0.2 is called steel. Pig iron is hard, but brittle; Steel is elastic; Wrought iron is easy to process, but softer than steel. Pig iron steelmaking is to reduce the carbon content in pig iron and remove impurities such as silicon, sulfur and phosphorus.
Element usage
Its biggest use is steelmaking; It is also widely used to make cast iron and wrought iron. Iron and its compounds are also used as magnets, dyes (ink, blue printed cloth, rouge pigment) and abrasives (red iron powder). Reduced iron powder is widely used in metallurgy.
Element auxiliary data
One of the main components of the crust. Iron is widely distributed in nature, but it was discovered and utilized later than gold and copper. First of all, there is no iron in the state of natural elements on the earth, which is easy to oxidize and rust. In addition, its melting point (1535℃) is much higher than that of copper (1083℃), and it is more difficult to smelt than copper.
Note that iron has valence +2 and valence +3. Here, the application of iron ions and ferrous ions in redox reaction should be mentioned. Meanwhile, pay attention to Fe3O4, which is a mixture of FeO and Fe2O3.
Pay attention to two equations of high school key Fe.
3Fe+8HNO3 (diluted) = = 3Fe (NO3) 2+2NO+4H2O
Fe+4HNO3 (diluted) = = Fe (NO3) 3+NO+2h2o
Under the same Fe content, the latter equation contains more nitric acid, which can oxidize Fe to +3 valence Fe ions, while the first equation can only oxidize to +2 valence Fe ions because of a small amount of nitric acid.