When people hear the word "metal", it is usually associated with a cold and solid substance that conducts electricity. However, metals and their alloys can be very different from each other. There are those that belong to the heavy group, these substances have the highest density. And some, such as lithium, are so light that they could float in water if only they did not actively react with it.
What metals are the most active?
But which metal exhibits the most intense properties? The most active metal is cesium. In terms of activity among all metals, it ranks first. Also, his "brothers" are considered francium, which is in second place, and ununenniy. But little is known about the properties of the latter.
Cesium properties
Cesium is an element that is similarly easy to melt in the hands. True, this can be done only under one condition: if the cesium is in a glass ampoule. Otherwise, the metal can quickly react with the surrounding air - ignite. And the interaction of cesium with water is accompanied by an explosion - such is the most active metal in its manifestation. This is the answer to the question of why it is so difficult to put cesium into containers.
In order to place it inside a test tube, it is necessary that it be made of special glass and filled with argon or hydrogen. The melting point of cesium is 28.7 o C. At room temperature, the metal is in a semi-liquid state. Cesium is a golden-white substance. In the liquid state, the metal reflects light well. Cesium vapor has a greenish-blue tint.
How was cesium discovered?
The most active metal was the first chemical element, the presence of which in the surface of the earth's crust was detected using the method of spectral analysis. When the scientists received the spectrum of the metal, they saw two sky-blue lines in it. Thus, this element got its name. The word caesius in Latin means "sky blue".
Discovery history
Its discovery belongs to the German researchers R. Bunsen and G. Kirchhoff. Even then, scientists were interested in which metals are active and which are not. In 1860, researchers studied the composition of water from the Durkheim Reservoir. They did this with the help of spectral analysis. In a water sample, scientists found elements such as strontium, magnesium, lithium, and calcium.
Then they decided to analyze a drop of water with a spectroscope. Then they saw two bright blue lines, located not far from each other. One of them practically coincided with the line of strontium metal in its position. Scientists decided that the substance they identified was unknown and attributed it to the group of alkali metals.
In the same year, Bunsen wrote a letter to his colleague, photochemist G. Roscoe, in which he spoke about this discovery. And officially, cesium was announced on May 10, 1860 at a meeting of scientists at the Berlin Academy. After six months, Bunsen was able to isolate about 50 grams of cesium chloroplatinite. Scientists processed 300 tons of mineral water and isolated about 1 kg of lithium chloride as a by-product in order to ultimately obtain the most active metal. This suggests that there is very little cesium in mineral waters.
The difficulty of obtaining cesium is constantly pushing scientists to search for minerals containing it, one of which is pollucite. But the extraction of cesium from ores is always incomplete; during operation, cesium dissipates very quickly. This makes it one of the most inaccessible substances in metallurgy. The earth's crust, for example, contains 3.7 grams of cesium per ton. And in one liter of sea water, only 0.5 micrograms of a substance is the most active metal. This leads to the fact that the extraction of cesium is one of the most labor-intensive processes.
Receipt in Russia
As mentioned, the main mineral from which cesium is obtained is pollucite. And also this most active metal can be obtained from a rare avogadrite. In industry, it is pollucite that is used. It was not mined in Russia after the collapse of the Soviet Union, despite the fact that even at that time gigantic reserves of cesium were discovered in the Voronya tundra near Murmansk.
By the time the domestic industry could afford to extract cesium, the license to develop this deposit was acquired by a company from Canada. Now the extraction of cesium is carried out by the Novosibirsk company CJSC Rare Metals Plant.
Use of cesium
This metal is used to make various solar cells. And also cesium compounds are used in special branches of optics - in the manufacture of infrared devices, cesium is used in the manufacture of sights that allow you to notice the equipment and manpower of the enemy. It is also used to make special metal halide lamps.
But this does not exhaust the scope of its application. On the basis of cesium, a number of medicines have also been created. These are drugs for the treatment of diphtheria, peptic ulcers, shock and schizophrenia. Like lithium salts, cesium salts have normothymic properties - or, simply, they are able to stabilize the emotional background.
francium metal
Another of the metals with the most intense properties is francium. It got its name in honor of the motherland of the discoverer of metal. M. Pere, who was born in France, discovered a new chemical element in 1939. It is one of those elements about which even chemists themselves find it difficult to draw any conclusions.
Francium is the heaviest metal. At the same time, the most active metal is francium, along with cesium. Francium possesses this rare combination - high chemical activity and low nuclear stability. Its longest-lived isotope has a half-life of only 22 minutes. Francium is used to detect another element - actinium. As well as francium salts, it was previously proposed to use for the detection of cancerous tumors. However, due to the high cost, this salt is unprofitable to produce.
Comparison of the most active metals
Ununennium is not yet a discovered metal. It will rank first in the eighth row of the periodic table. The development and research of this element is carried out in Russia at the Joint Institute for Nuclear Research. This metal will also have to have a very high activity. If we compare the already known francium and cesium, then francium will have the highest ionization potential - 380 kJ / mol.
For cesium, this figure is 375 kJ/mol. But francium still does not react as quickly as cesium. Thus, cesium is the most active metal. This is the answer (chemistry is most often the subject in the curriculum of which you can find a similar question), which can be useful both in the classroom at school and in vocational school.
In the section on the question Active metals, what are these metals? given by the author Olesya Oleskina the best answer is Those that donate electrons most easily.
The activity of metals in the Mendeleev system increases from top to bottom and from right to left, thus, the most active is francium, on the last layer of which there is 1 electron located far enough from the nucleus.
Active - alkali metals (Li, Na, K, Rb, Cs, Fr)
They are inferior to alkaline earth (Ca, Sr, BA, Ra)
Stirlitz
Artificial intelligence
(116389)
They are not classified as alkaline earth
Answer from Natalia Kosenko[guru]
Those that react easily
Answer from Reader.[guru]
Rapidly oxidizing in air, sodium, potassium, lithium.
Answer from KSY[guru]
Eu, Sm, Li, Cs, Rb, K, Ra, Ba, Sr, Ca, Na, Ac, La, Ce, Pr, Nd, Pm, Gd, Tb, Mg, Y, Dy, Am, Ho, Er, Tm, Lu, Sc, Pu, Th, Np, U, Hf, Be, Al, Ti, Zr, Yb, Mn, V, Nb, Pa, Cr, Zn, Ga, Fe, Cd, In, Tl, Co, Ni, Te, Mo, Sn, Pb, H2, W, Sb, Bi, Ge, Re, Cu, Tc, Te, Rh, Po, Hg, Ag, Pd, Os, Ir, Pt, Au
Answer from Durchlaucht Furst[guru]
Alkali metals are elements of the main subgroup of Group I of the Periodic Table of Chemical Elements of D. I. Mendeleev: lithium Li, sodium Na, potassium K, rubidium Rb, cesium Cs and francium Fr. These metals are called alkaline because most of their compounds are soluble in water. In Slavic, "leach" means "dissolve", and this determined the name of this group of metals. When alkali metals are dissolved in water, soluble hydroxides are formed, called alkalis.
Due to the high chemical activity of alkali metals in relation to water, oxygen, nitrogen, they are stored under a layer of kerosene. To carry out the reaction with an alkali metal, a piece of the required size is carefully cut off with a scalpel under a layer of kerosene, the metal surface is thoroughly cleaned from the products of its interaction with air in an argon atmosphere, and only then the sample is placed in the reaction vessel.
Impersonal metal account on Wikipedia
Impersonal metal account
Common squirrel on Wikipedia
Check out the wikipedia article on common squirrel
Alkali metals on Wikipedia
Check out the wikipedia article on alkali metals
All metals, depending on their redox activity, are combined into a series called the electrochemical voltage series of metals (since the metals in it are arranged in order of increasing standard electrochemical potentials) or a series of metal activity:
Li, K, Ba, Ca, Na, Mg, Al, Zn, Fe, Ni, Sn, Pb, H 2 , Cu, Hg, Ag, Рt, Au
The most reactive metals are in the order of activity up to hydrogen, and the more to the left the metal is located, the more active it is. Metals that are next to hydrogen in the activity series are considered inactive.
Aluminum
Aluminum is a silvery white color. The main physical properties of aluminum are lightness, high thermal and electrical conductivity. In the free state, when exposed to air, aluminum is covered with a strong oxide film Al 2 O 3 , which makes it resistant to concentrated acids.
Aluminum belongs to the p-family metals. The electronic configuration of the external energy level is 3s 2 3p 1 . In its compounds, aluminum exhibits an oxidation state equal to "+3".
Aluminum is obtained by electrolysis of the molten oxide of this element:
2Al 2 O 3 \u003d 4Al + 3O 2
However, due to the low yield of the product, the method of obtaining aluminum by electrolysis of a mixture of Na 3 and Al 2 O 3 is more often used. The reaction proceeds when heated to 960C and in the presence of catalysts - fluorides (AlF 3 , CaF 2 , etc.), while aluminum is released at the cathode, and oxygen is released at the anode.
Aluminum is able to interact with water after removing the oxide film from its surface (1), interact with simple substances (oxygen, halogens, nitrogen, sulfur, carbon) (2-6), acids (7) and bases (8):
2Al + 6H 2 O \u003d 2Al (OH) 3 + 3H 2 (1)
2Al + 3 / 2O 2 \u003d Al 2 O 3 (2)
2Al + 3Cl 2 = 2AlCl 3 (3)
2Al + N 2 = 2AlN (4)
2Al + 3S \u003d Al 2 S 3 (5)
4Al + 3C \u003d Al 4 C 3 (6)
2Al + 3H 2 SO 4 \u003d Al 2 (SO 4) 3 + 3H 2 (7)
2Al + 2NaOH + 3H 2 O \u003d 2Na + 3H 2 (8)
Calcium
In its free form, Ca is a silvery-white metal. When exposed to air, it instantly becomes covered with a yellowish film, which is the product of its interaction with the constituent parts of the air. Calcium is a fairly hard metal, has a cubic face-centered crystal lattice.
The electronic configuration of the external energy level is 4s 2 . In its compounds, calcium exhibits an oxidation state equal to "+2".
Calcium is obtained by electrolysis of molten salts, most often chlorides:
CaCl 2 \u003d Ca + Cl 2
Calcium is able to dissolve in water with the formation of hydroxides that exhibit strong basic properties (1), react with oxygen (2), forming oxides, interact with non-metals (3-8), dissolve in acids (9):
Ca + H 2 O \u003d Ca (OH) 2 + H 2 (1)
2Ca + O 2 \u003d 2CaO (2)
Ca + Br 2 \u003d CaBr 2 (3)
3Ca + N 2 \u003d Ca 3 N 2 (4)
2Ca + 2C = Ca 2 C 2 (5)
2Ca + 2P = Ca 3 P 2 (7)
Ca + H 2 \u003d CaH 2 (8)
Ca + 2HCl \u003d CaCl 2 + H 2 (9)
Iron and its compounds
Iron is a gray metal. In its pure form, it is quite soft, malleable and ductile. The electronic configuration of the external energy level is 3d 6 4s 2 . In its compounds, iron exhibits the oxidation states "+2" and "+3".
Metallic iron reacts with water vapor, forming a mixed oxide (II, III) Fe 3 O 4:
3Fe + 4H 2 O (v) ↔ Fe 3 O 4 + 4H 2
In air, iron is easily oxidized, especially in the presence of moisture (it rusts):
3Fe + 3O 2 + 6H 2 O \u003d 4Fe (OH) 3
Like other metals, iron reacts with simple substances, for example, halogens (1), dissolves in acids (2):
Fe + 2HCl \u003d FeCl 2 + H 2 (2)
Iron forms a whole range of compounds, since it exhibits several oxidation states: iron (II) hydroxide, iron (III) hydroxide, salts, oxides, etc. So, iron (II) hydroxide can be obtained by the action of alkali solutions on iron (II) salts without air access:
FeSO 4 + 2NaOH \u003d Fe (OH) 2 ↓ + Na 2 SO 4
Iron(II) hydroxide is soluble in acids and oxidized to iron(III) hydroxide in the presence of oxygen.
Salts of iron (II) exhibit the properties of reducing agents and are converted into iron (III) compounds.
Iron oxide (III) cannot be obtained by the combustion reaction of iron in oxygen; to obtain it, it is necessary to burn iron sulfides or calcinate other iron salts:
4FeS 2 + 11O 2 \u003d 2Fe 2 O 3 + 8SO 2
2FeSO 4 \u003d Fe 2 O 3 + SO 2 + 3H 2 O
Iron (III) compounds exhibit weak oxidizing properties and are able to enter into OVR with strong reducing agents:
2FeCl 3 + H 2 S \u003d Fe (OH) 3 ↓ + 3NaCl
Iron and steel production
Steels and cast irons are alloys of iron with carbon, and the carbon content in steel is up to 2%, and in cast iron 2-4%. Steels and cast irons contain alloying additives: steels - Cr, V, Ni, and cast iron - Si.
There are various types of steels, so, according to their purpose, structural, stainless, tool, heat-resistant and cryogenic steels are distinguished. According to the chemical composition, carbon (low, medium and high carbon) and alloyed (low, medium and high alloyed) are distinguished. Depending on the structure, austenitic, ferritic, martensitic, pearlitic and bainitic steels are distinguished.
Steels have found application in many sectors of the national economy, such as construction, chemical, petrochemical, environmental protection, transport energy and other industries.
Depending on the form of carbon content in cast iron - cementite or graphite, as well as their quantity, several types of cast iron are distinguished: white (light color of the fracture due to the presence of carbon in the form of cementite), gray (gray color of the fracture due to the presence of carbon in the form of graphite ), malleable and heat resistant. Cast irons are very brittle alloys.
The areas of application of cast iron are extensive - artistic decorations (fences, gates), body parts, plumbing equipment, household items (pans) are made from cast iron, it is used in the automotive industry.
Examples of problem solving
EXAMPLE 1
| Exercise | An alloy of magnesium and aluminum weighing 26.31 g was dissolved in hydrochloric acid. In this case, 31.024 liters of colorless gas were released. Determine the mass fractions of metals in the alloy. |
| Decision | Both metals are capable of reacting with hydrochloric acid, as a result of which hydrogen is released: Mg + 2HCl \u003d MgCl 2 + H 2 2Al + 6HCl \u003d 2AlCl 3 + 3H 2 Find the total number of moles of hydrogen released: v(H 2) \u003d V (H 2) / V m v (H 2) \u003d 31.024 / 22.4 \u003d 1.385 mol Let the amount of substance Mg be x mol, and Al be y mol. Then, based on the reaction equations, we can write an expression for the total number of moles of hydrogen: x + 1.5y = 1.385 We express the mass of metals in the mixture: Then, the mass of the mixture will be expressed by the equation: 24x + 27y = 26.31 We got a system of equations: x + 1.5y = 1.385 24x + 27y = 26.31 Let's solve it: 33.24 -36y + 27y \u003d 26.31 v(Al) = 0.77 mol v(Mg) = 0.23mol Then, the mass of metals in the mixture: m (Mg) \u003d 24 × 0.23 \u003d 5.52 g m(Al) \u003d 27 × 0.77 \u003d 20.79 g Find the mass fractions of metals in the mixture: ώ =m(Me)/m sum ×100% ώ(Mg) = 5.52 / 26.31 × 100% = 20.98% ώ(Al) = 100 - 20.98 = 79.02% |
| Answer | Mass fractions of metals in the alloy: 20.98%, 79.02% |
Metals that react easily are called active metals. These include alkali, alkaline earth metals and aluminium.
Position in the periodic table
The metallic properties of the elements weaken from left to right in Mendeleev's periodic table. Therefore, elements of groups I and II are considered the most active.
Rice. 1. Active metals in the periodic table.
All metals are reducing agents and easily part with electrons at the external energy level. Active metals have only one or two valence electrons. In this case, the metallic properties are enhanced from top to bottom with an increase in the number of energy levels, because. the farther an electron is from the nucleus of an atom, the easier it is for it to separate.
Alkali metals are considered the most active:
- lithium;
- sodium;
- potassium;
- rubidium;
- cesium;
- francium.
The alkaline earth metals are:
- beryllium;
- magnesium;
- calcium;
- strontium;
- barium;
- radium.
You can find out the degree of activity of a metal by the electrochemical series of metal voltages. The more to the left of hydrogen an element is located, the more active it is. The metals to the right of hydrogen are inactive and can only interact with concentrated acids.
Rice. 2. Electrochemical series of voltages of metals.
The list of active metals in chemistry also includes aluminum, located in group III and to the left of hydrogen. However, aluminum is located on the border of active and medium active metals and does not react with certain substances under normal conditions.
Properties
Active metals are soft (can be cut with a knife), light, and have a low melting point.
The main chemical properties of metals are presented in the table.
|
Reaction |
The equation |
Exception |
|
Alkali metals ignite spontaneously in air, interacting with oxygen |
K + O 2 → KO 2 |
Lithium reacts with oxygen only at high temperatures. |
|
Alkaline earth metals and aluminum form oxide films in air, and spontaneously ignite when heated. |
2Ca + O 2 → 2CaO |
|
|
React with simple substances to form salts |
Ca + Br 2 → CaBr 2; |
Aluminum does not react with hydrogen |
|
React violently with water, forming alkalis and hydrogen |
|
The reaction with lithium proceeds slowly. Aluminum reacts with water only after the removal of the oxide film. |
|
React with acids to form salts |
Ca + 2HCl → CaCl 2 + H 2; 2K + 2HMnO 4 → 2KMnO 4 + H 2 |
|
|
React with salt solutions, first reacting with water and then with salt |
2Na + CuCl 2 + 2H 2 O: 2Na + 2H 2 O → 2NaOH + H 2; |
Active metals easily react, therefore, in nature they are found only in mixtures - minerals, rocks.
Rice. 3. Minerals and pure metals.
What have we learned?
Active metals include elements of groups I and II - alkali and alkaline earth metals, as well as aluminum. Their activity is due to the structure of the atom - a few electrons are easily separated from the external energy level. These are soft light metals that quickly react with simple and complex substances, forming oxides, hydroxides, salts. Aluminum is closer to hydrogen and its reaction with substances requires additional conditions - high temperatures, destruction of the oxide film.
At room temperature (20 °C), all metals, except for mercury, are in a solid state and conduct heat and well. When cut, metals glisten and some, like iron and nickel, are magnetic. Many metals are ductile - they can be used to make wire - and forging - it is easy to give them a different shape.
noble metals
Noble metals in the earth's crust are found in pure form, and not in the composition of compounds. These include copper, silver, gold and platinum. They are chemically passive and hardly enter into with others. Copper is a noble metal. Gold is one of the most inert elements. Due to their inertness, noble metals are not susceptible to corrosion, so jewelry and coins are made from them. Gold is so inert that ancient gold pieces still shine brightly.
alkali metals
Group 1 in the periodic table consists of 6 very active metals, incl. sodium and potassium. They melt at a relatively low temperature (the melting point of potassium is 64°C) and are so soft that they can be cut with a knife. Reacting with water, these metals form an alkaline solution and are therefore called alkaline. Potassium reacts violently with water. At the same time, it is released, which burns with a lilac flame.
alkaline earth metals
The six metals that make up the 2nd group (including magnesium and calcium) are called alkaline earth metals. These metals are part of many minerals. So, calcium is present in calcite, the veinlets of which can be found in limestone and chalk. Alkaline earth metals are less reactive than alkali metals, they are harder and melt at a higher temperature. Calcium is found in shells, bones and sponges. Magnesium is part of chlorophyll, the green pigment needed for photosynthesis.
Metals of the 3rd and 4th groups
The seven metals of these groups are located in the periodic table to the right of the transition metals. Aluminum is one of the least dense metals, so it is lightweight. But lead is very dense; it is used to make screens that protect against x-rays. All these metals are quite soft and melt at a relatively low temperature. Many of them are used in alloys - mixtures of metals created for specific purposes. Bicycles and airplanes are made from aluminum alloys.
transition metals
Transition metals have typically metallic properties. They are strong, hard, shiny and melt at high temperatures. They are less reactive than the alkali and alkaline earth metals. These include iron, gold, silver, chromium, nickel, copper. They are all malleable and are widely used in industry - both in pure form and in the form of alloys. About 77% of the mass of the car is made up of metals, mainly steel, i.e. an alloy of iron and carbon (see the article ""). Wheel hubs are made of chrome-plated steel - for shine and corrosion protection. The body of the machine is made of sheet steel. Steel bumpers protect the car in the event of a collision.
Activity row
The position of the metal in the activity series indicates how readily the metal reacts. The more active the metal, the more easily it takes away oxygen from less active metals. Active metals are difficult to isolate from compounds, while inactive metals are found in pure form. Potassium and sodium are stored in kerosene, as they instantly react with water and air. Copper is the least active of the inexpensive metals. It is used in the production of pipes, hot water tanks and electrical wires.
Metals and flames
Some metals, when brought near a fire, give the flame a certain hue. The presence of a particular metal in the compound can be determined by the color of the flame. To do this, a grain of substance is placed in a flame at the end of a wire made of inert platinum. Sodium compounds color the flame yellow, copper compounds blue-green, calcium compounds red, and potassium compounds lilac. The composition of fireworks includes different metals, giving the flame different shades. Barium is green, strontium is red, sodium is yellow, and copper is blue-green.
Corrosion
Corrosion is a chemical reaction that occurs when a metal comes into contact with air or water. The metal interacts with atmospheric oxygen, and an oxide is formed on its surface. The metal loses its luster and becomes coated. Highly active metals corrode faster than less active ones. Knights lubricated steel armor with oil or wax so that it would not rust (steel contains a lot of iron). To protect against rust, the steel car body is covered with several layers of paint. Some metals (for example, aluminum) are covered with a dense oxide film that protects them. Iron, when corroded, forms a loose oxide film, which, when reacted with water, gives rust. The rust layer easily crumbles, and the corrosion process spreads in depth. To protect against corrosion, steel cans are coated with a layer of tin, a less active metal. Large structures, such as bridges, are protected from corrosion by paint. Moving parts of machines, such as bicycle chains, are lubricated with oil to prevent corrosion.
The method of protecting steel from corrosion by coating with a layer of zinc is called galvanization. Zinc is more active than steel, so it “draws” oxygen from it. Even if the zinc layer gets scratched, the oxygen in the air will react faster with the zinc than with the iron. To protect ships from corrosion, blocks of zinc or magnesium are attached to their hulls, which corrode themselves, but protect the ship. For additional protection against corrosion, the steel sheets of the car body are cleanly galvanized before painting. From the inside they are sometimes covered with plastic.
How metals were discovered
People probably learned how to get metals by chance, when metals were released from minerals when they were heated in charcoal furnaces. Pure metal is released from the compound during the reduction reaction. 
The action of blast furnaces is based on such reactions. Around 4000 BC The Sumerians (find out more in the article "") made gold, silver and copper helmets and daggers. First of all, people learned to process copper, gold and silver, i.e. noble metals because they occur in their pure form. Around 3500 BC The Sumerians learned how to make bronze - an alloy of copper and tin. Bronze is stronger than noble metals. Iron was discovered later, since very high temperatures are needed to extract it from compounds. The drawing on the right shows a bronze ax (500 BC) and a Sumerian bronze bowl.
Before 1735, people knew only a few metals: copper, silver, gold, iron, mercury, tin, zinc, bismuth, antimony and lead. Aluminum was discovered in 1825. Nowadays, scientists have synthesized a number of new metals by irradiating uranium with neutrons and other elementary particles in a nuclear reactor. These elements are unstable and decay very quickly.
