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Tasks 3. Periodic table
Answer:
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
It is known that with an increase in the ordinal number of an element in periods, the metallic properties of atoms decrease, and in groups they increase. Arrange, in order of increasing metallic properties, the following elements: Write down the designations of the elements in the desired sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
It is known that with an increase in the ordinal number of an element in periods, the metallic properties of atoms decrease, and in groups they increase. Arrange, in order of increasing metallic properties, the following elements:
Write down the designations of the elements in the desired sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
It is known that with an increase in the ordinal number of an element in periods, the metallic properties of atoms decrease, and in groups they increase. Arrange, in order of increasing metallic properties, the following elements:
Write down the designations of the elements in the desired sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
It is known that with an increase in the ordinal number of an element in periods, the metallic properties of atoms decrease, and in groups they increase. Arrange, in order of increasing metallic properties, the following elements:
Write down the designations of the elements in the desired sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
It is known that with an increase in the ordinal number of an element in periods, the metallic properties of atoms decrease, and in groups they increase. Arrange, in order of increasing metallic properties, the following elements:
Write down the designations of the elements in the desired sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
It is known that with an increase in the ordinal number of an element in periods, the metallic properties of atoms decrease, and in groups they increase. Arrange, in order of increasing metallic properties, the following elements: Write down the designations of the elements in the desired sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
It is known that with an increase in the ordinal number of an element in periods, the metallic properties of atoms decrease, and in groups they increase. Arrange, in order of increasing metallic properties, the following elements:
Write down the designations of the elements in the desired sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
It is known that with an increase in the ordinal number of an element in periods, the metallic properties of atoms decrease, and in groups they increase. Arrange, in order of increasing metallic properties, the following elements:
Write down the designations of the elements in the desired sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
Periodic table of chemical elements of D.I. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups, they increase.
Considering these patterns, arrange the following elements in order of increasing radius of atoms: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
Periodic table of chemical elements of D.I. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups, they increase.
Considering these patterns, arrange the following elements in order of increasing radius of atoms: Write down the signs of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
Periodic table of chemical elements of D.I. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups, they increase.
Considering these patterns, arrange the following elements in order of decreasing radius of atoms: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element, the electronegativity of atoms increases in periods, and decreases in groups.
Considering these patterns, arrange the following elements in order of increasing electronegativity: Write down the designations of the elements in the desired sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of changes in these properties, about the methods of obtaining substances, as well as about their finding in nature. For example, it is known that with an increase in the ordinal number of a chemical element, the electronegativity of atoms increases in periods, and decreases in groups.
Considering these patterns, arrange the following elements in order of decreasing electronegativity: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
Taking into account these regularities, arrange the following elements in the order of strengthening of the acidic properties of higher oxides: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
Periodic table of chemical elements of D.I. For example, it is known that the acidic nature of higher oxides of elements in periods with an increase in the nuclear charge increases, and in groups it decreases.
Considering these patterns, arrange the following elements in the order of weakening of the acidic properties of higher oxides: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
Periodic table of chemical elements of D.I. For example, it is known that acidic
the character of anoxic acids increases with an increase in the charge of the atomic nucleus, both in periods and in groups.
Considering these patterns, arrange the hydrogen compounds in the order of increasing acidic properties:
In the answer, indicate the numbers of the chemical formulas in the desired sequence.
Answer:
Periodic table of chemical elements of D.I. So, for example, it is known that the ease of the release of electrons by atoms of elements in periods with an increase in the charge of the nucleus decreases, and in groups it increases.
Considering these patterns, arrange the following elements in order of increasing ease of electron recoil: Write down the designations of the elements in the required sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
Periodic table of chemical elements D.I. Mendeleev - a rich repository of information about chemical elements, their properties and the properties of their compounds, about the patterns of change in these properties, about the methods of obtaining substances, as well as about their finding in nature. So, for example, it is known that with an increase in the ordinal number of a chemical element in periods, the radii of atoms decrease, and in groups they increase.
Considering these patterns, arrange the following elements in order of decreasing atomic radius: N, Al, C, Si. Write down the designations of the elements in the desired sequence.
In your answer, specify the element designations by separating &. For example, 11 & 22.
Answer:
Periodic table of chemical elements D.I. Mendeleev - a rich repository of information about chemical elements, their properties and the properties of their compounds. For example, it is known that with an increase in the ordinal number of a chemical element, the basic character of the oxide decreases in periods, and increases in groups.
Considering these regularities, arrange the following elements in order of increasing the basicity of oxides: Na, Al, Mg, B. Write down the symbols of the elements in the required sequence.
Answer:
Periodic table of chemical elements D.I. Mendeleev - a rich repository of information about chemical elements, their properties and the properties of their compounds. For example, it is known that with an increase in the ordinal number of a chemical element, the basic character of the oxide decreases in periods, and increases in groups. Considering these regularities, arrange the following elements in the order of increasing the basicity of oxides: Mg, Al, K, Ca. Write down the symbols of the elements in the desired sequence.
Answer:
Considering these patterns, arrange the following elements in order of increasing electronegativity: chlorine, silicon, sulfur, phosphorus. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
Considering these patterns, arrange the following elements in order of increasing the regenerative ability: calcium, sodium, magnesium, potassium. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
Considering these patterns, arrange the following elements in decreasing order of atomic radii: aluminum, carbon, boron, silicon. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
Considering these regularities, arrange the following elements in order of increasing acidic properties of their higher oxides: silicon, chlorine, phosphorus, sulfur. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the ordinal number of a chemical element, the basic properties of oxides in periods weaken, and in groups they increase.
Considering these patterns, arrange the following elements in order of weakening of the main properties of their oxides: aluminum, phosphorus, magnesium, silicon. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the serial number of a chemical element, the acidic properties of higher hydroxides in periods increase, and in groups it weakens.
Considering these regularities, arrange the following elements in order of increasing acidic properties of their higher hydroxides: carbon, boron, beryllium, nitrogen. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the ordinal number of a chemical element, the basic character of hydroxides weakens in periods, and increases in groups.
Considering these regularities, arrange the following elements in order of strengthening the main properties of their hydroxides: calcium, beryllium, strontium, magnesium. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the serial number of a chemical element, the ability of atoms to accept electrons - electronegativity - increases in periods, and weakens in groups.
Considering these patterns, arrange the following elements in order of decreasing electronegativity: nitrogen, oxygen, boron, carbon. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the serial number of a chemical element, the ability of atoms to donate electrons - the reductive ability - weakens in periods, and increases in groups.
Considering these patterns, arrange the following elements in the order of weakening of the reductive ability: nitrogen, fluorine, carbon, oxygen. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the ordinal number of a chemical element, the radii of atoms in periods decrease, and in groups they increase.
Considering these patterns, arrange the following elements in order of increasing radii of atoms: oxygen, fluorine, sulfur, chlorine. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the ordinal number of a chemical element, the acidic character of higher oxides increases in periods, and weakens in groups.
Considering these patterns, arrange the following elements in the order of weakening of the acidic properties of their higher oxides: silicon, chlorine, phosphorus, sulfur. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
Considering these regularities, arrange the following elements in order of strengthening the basic properties of their oxides: aluminum, sodium, magnesium, silicon. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the serial number of a chemical element, the acidic properties of higher hydroxides (acids) in periods increases, and in groups it weakens.
Considering these regularities, arrange the following elements in the order of weakening of the acidic properties of their higher hydroxides: carbon, boron, beryllium, nitrogen. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the serial number of a chemical element, the ability of atoms to accept electrons - electronegativity - increases in periods, and weakens in groups.
Considering these patterns, arrange the following elements in order of increasing electronegativity: nitrogen, fluorine, carbon, oxygen. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the serial number of a chemical element, the ability to donate electrons - the reductive ability - weakens in periods, and increases in groups.
Considering these patterns, arrange the following elements in order of increasing the reductive ability: rubidium, sodium, lithium, potassium. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the ordinal number of a chemical element, the radii of atoms in periods decrease, and in groups they increase.
Considering these patterns, arrange the following elements in decreasing order of atomic radii: phosphorus, carbon, nitrogen, silicon. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the ordinal number of a chemical element, the acidic character of higher oxides increases in periods, and weakens in groups.
Considering these regularities, arrange the following elements in order of increasing acidic properties of their higher oxides: aluminum, sulfur, silicon, phosphorus. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the serial number of a chemical element, the basic properties of oxides in periods weaken, and in groups they increase.
Considering these patterns, arrange the following elements in order of weakening of the main properties of their oxides: magnesium, potassium, sodium, calcium. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the ordinal number of a chemical element, the radii of atoms in periods decrease, and in groups they increase.
Considering these patterns, arrange the following elements in increasing order of atomic radii: carbon, boron, beryllium, nitrogen. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
2019 was declared the International Year of the Periodic Table of Chemical Elements of D. I. Mendeleev. The world scientific community will celebrate the 150th anniversary of the discovery of the Periodic Law of Chemical Elements by D.I.Mendeleev in 1869. DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the serial number of a chemical element, the radii of atoms in periods decrease, and in groups they increase. Considering these patterns, arrange the following elements in decreasing order of atomic radii: aluminum, phosphorus, silicon. In the answer, write down the symbols of the elements in the desired sequence.
Answer:
2019 was declared the International Year of the Periodic Table of Chemical Elements of D. I. Mendeleev. The world scientific community will celebrate the 150th anniversary of the discovery of the Periodic Law of Chemical Elements by D.I.Mendeleev in 1869. DI Mendeleev's Periodic Table of Chemical Elements is a rich repository of information about chemical elements, their properties and the properties of their compounds. So, for example, it is known that with an increase in the ordinal number of a chemical element, the acidic character of higher oxides increases in periods, and weakens in groups. Considering these regularities, arrange the following elements in order of increasing acidic properties of their higher oxides: chlorine, phosphorus, sulfur. In the answer, write down the symbols of the elements in the desired sequence.
All substances are conventionally divided into conductors and dielectrics according to their ability to conduct electric current. Semiconductors occupy an intermediate position between them. By conductors we mean substances in which there are free charge carriers that can move under the action of an electric field. Conductors are metals, solutions or molten salts, acids and alkalis. Metals, due to their unique properties of electrical conductivity, are widely used in electrical engineering. For the transmission of electricity, mainly copper and aluminum wires are used, in exceptional cases, silver. electrical wiring is supposed to be carried out only with copper wires. Aluminum wires are still used because of their cheapness, as well as in cases where their use is completely justified and does not pose a danger. Aluminum wires are allowed to power stationary consumers with a known in advance, guaranteed power, for example, pumps , air conditioners, fans, household outlets with a load of up to 1 kW, as well as for external electrical wiring (overhead lines, underground cables, etc.) In dwellings, only copper-based wires are allowed. Metals in a solid state have a crystalline structure. Particles in crystals are arranged in a certain order, forming a spatial (crystal) lattice. The nodes of the crystal lattice are positive ions, and free electrons move in the space between them, which are not connected with the nuclei of their atoms. electrons are called electron gas. Under normal conditions, the metal is electrically neutral, because. The total negative charge of all free electrons in absolute value is equal to the positive charge of all lattice ions. The carriers of free charges in metals are electrons. Their concentration is quite high. These electrons participate in random thermal motion. Under the influence of an electric field, free electrons begin to move in an orderly manner along the conductor. the fact that electrons in metals serve as carriers of electric current was proved by a simple experiment by the German physicist Karl Ricke back in 1899 He took three cylinders of the same radius: copper, aluminum and copper, arranged them one after another, pressed them with their ends and included them in the tram line , and then for more than a year passed an electric current through them. After that, he investigated the contact points of the metal cylinders and did not find aluminum atoms in copper, but copper atoms in aluminum, i.e. From this, he concluded that when an electric current passes through a conductor, the ions remain stationary, and only free electrons move, which are the same for all substances and are not associated with the difference in their physicochemical properties. So, the electric current in metal conductors is an ordered movement of free electrons under the action of an electric field. The speed of this movement is small - a few millimeters per second, and sometimes even less. But as soon as an electric field appears in the conductor, it is at a tremendous speed, close to the speed of light in a vacuum (300,000 k / s), propagates along the entire length of the conductor. Simultaneously with the propagation of the electric field, all electrons begin to move in one direction along the entire length of the conductor. For example, when the circuit of an electric lamp is closed, and the electrons present in the spiral of the lamp. When we talk about the speed of propagation of an electric current in a conductor, we mean the speed of propagation of an electric field along the conductor. An electric signal sent, for example, by wires from Moscow to Vladivostok (distance of about 8000 km), arrives there in about 0.03 s. Dielectrics or insulators are substances in which there are no free charge carriers, and therefore they do not conduct electric current. Such substances are referred to as ideal dielectrics. For example, glass, porcelain, earthenware and marble are good insulators in a cold state. Crystals of these materials have ionic structure, i.e. are composed of positively and negatively charged ions. Their electric charges are bound in the crystal lattice and are not free, which makes these materials dielectrics. Under real conditions, dielectrics conduct an electric current, not very weakly. To ensure their conductivity, a very high voltage must be applied. The conductivity of dielectrics is less than that of conductors. This is due to the fact that under normal conditions the charges in dielectrics are bound into stable molecules and they are not in state, as in conductors, it is easy to break off and become free. The electric current passing through dielectrics is proportional to the strength of the electric field. At a certain critical value of the electric field strength, an electrical breakdown occurs. The value is called the dielectric strength and is measured in V / cm. Many dielectrics due to their high dielectric strength is used mainly as electrical insulating materials. Semiconductors do not conduct electric current at low voltages, and with increasing voltage they become electrically conductive. Unlike conductors (metals), their conductivity increases with increasing temperature. This is especially noticeable, for example, in transistor radios, which do not work well in hot weather. Semiconductors are characterized by a strong dependence of electrical conductivity on external influences. Semiconductors are widely used in various electrical devices, since their electrical conductivity can be controlled.
PART 1
1. Metals (M) are located in groups I-III, or in the lower part of groups IV-VI. Only metals are B groups.
2. Metal atoms have 1-3 electrons in the outer electron layer and a relatively large radius of the atom. Metal atoms tend to donate external electrons.
3. Simple substances- metals consist of elements linked by a metallic chemical bond, which can be displayed by the general scheme:
4. All M - solids except for Hg. The softest metals of group IA, the hardest - Cr.
5. M have thermal and electrical conductivity and have a metallic luster.
6. Tin has the property of forming two simple substances- white and gray, that is, by the property of allotropy.
7. Complete the table "Properties and uses of some metals".
PART 2
1. Select the names of simple substances - metals. From the letters corresponding to the correct answers, you will compose the name of the metal, which in Greek means "stone": lithium.
2) magnesium L
3) calcium AND
5) copper T
7) gold and
8) mercury Y
2. The following statements characterizing metals are incorrect:
5) non-plastic and non-forging
3. Select the four most conductive metals (place the numbers in descending order of conductivity) from the list:
1) silver
2) gold
3) aluminum
4) iron
5) manganese
6) potassium
7) sodium
Answer: 1, 2, 3, 7.
4. Make schemes for the formation of a metallic chemical bond for substances with the formulas:
5. Analyze the picture "Metal crystal lattice".
Make a conclusion about the reasons for the plasticity, thermal and electrical conductivity of metals.
Each metal atom is surrounded by eight neighboring atoms. The detached outer electrons freely move from one formed ion to another, connecting the ionic core of the metal into a giant molecule. High thermal conductivity, electrical conductivity of metals are due to the presence in their crystal lattices of mobile electrons moving under the action of an electric field. Most metals are plastic due to the displacement of layers of metal atoms without breaking the bond between them.
6. Fill in the "Metals" table. Find the data for the table using additional sources of information, including the Internet.
7. Using the Internet and other sources of information, prepare a short message on the topic "Mercury in Human Life" according to the following plan:
1) knowledge about mercury in antiquity and the Middle Ages;
2) toxicity of mercury and safety measures when working with it;
3) the use of mercury in modern industry.
1) Mercury was one of the 7 metals, it is considered the progenitor of all metals, they used not only mercury itself, but also its alloy, cinnabar.
2) It is very toxic, evaporates at room temperature, and, if inhaled, poisons a person. Accumulating in the body, it affects the internal organs, respiratory tract, hematopoietic organs and the brain.
3) Mercury is widely used. In the chemical industry as a cathode in the production of sodium hydroxide, as a catalyst in the production of many organic compounds, in the dissolution of uranium blocks (in nuclear power). This element is used in the manufacture of fluorescent lamps, quartz lamps, pressure gauges, thermometers and other scientific instruments.
Conductivity
Superconductivity theory
When the crystal lattices of solids are formed from atoms of various substances, valence electrons located in the outer orbits of atoms interact with each other in different ways and, as a result, behave differently (see strip
theory of solid-state superconductivity and theory
molecular orbitals). Thus, the freedom of valence electrons to move inside a substance is determined by its molecular crystal structure. On the whole, according to the electrically conductive properties, all substances can (with some degree of convention) be subdivided into three categories, each of which has pronounced characteristics of the behavior of valence electrons under the influence of an external electric field.
Conductors
In some substances, valence electrons move freely between atoms. First of all, this category includes metals in which the electrons of the outer shells are literally in the "common property" of the atoms of the crystal lattice (see.
chemical bonds and electronic theory of conduction).
If you apply an electric voltage to such a substance (for example, connect the poles of a storage battery to its two ends), the electrons will begin an unobstructed ordered movement in the direction of the south pole of the potential difference, thereby creating an electric current. Conductive substances of this kind are usually called conductors. The most common conductors in technology are, of course, metals, primarily copper and aluminum, which have a minimum electrical resistance and are quite widespread in earthly nature. It is from them that high-voltage electrical cables and household electrical wiring are mainly made. There are other types of materials with good electrical conductivity, such as saline, alkaline and acid solutions, as well as plasma and some types of long organic molecules.
In this regard, it is important to remember that electrical conductivity can be due to the presence in a substance not only of free electrons, but also of free positively and negatively charged ions of chemical compounds. In particular, even in ordinary tap water, so many different salts are dissolved, decomposing when dissolved into negatively charged cations and positively charged anions, that water (even fresh) is a very good conductor, and this should not be forgotten when working with electrical equipment in conditions of high humidity - otherwise, you can get a very noticeable electric shock.
Insulators
In many other substances (in particular, glass, porcelain, plastics), electrons are firmly attached to atoms or molecules and
not capable of free movement under the influence of an external electric voltage applied. These materials are called insulators.
Most often in modern technology, various plastics are used as electrical insulators. In fact, any plastic consists of polymer molecules - that is, very long chains of organic (hydrogen-carbon) compounds - which, moreover, form complex and very strong interweaving. The easiest way to imagine a polymer structure is to imagine a plate of tangled and stuck together long and thin noodles. In such materials, electrons are firmly attached to their ultra-long molecules and are unable to leave them under the influence of external stress. Amorphous substances such as glass, porcelain or rubber, which do not have a rigid crystalline structure, also have good insulating properties. They are also often used as electrical insulators.
Both conductors and insulators play an important role in our technogenic civilization, which uses electricity as the main means of transmitting energy over a distance. Electricity travels through conductors from power plants to our homes and to all kinds of industrial enterprises, and insulators ensure our safety, protecting us from the destructive consequences of direct contact of the human body with high electrical voltage.
Semiconductors
Finally, there is a small category of chemical elements that occupy an intermediate position between metals and insulators (the most famous of which are silicon and germanium). In the crystal lattices of these substances, all the valence electrons, at first glance, are linked by chemical bonds and free electrons to ensure electrical conductivity, it would seem, should not remain. However, in reality, the situation looks somewhat different, since some of the electrons are knocked out of their outer orbits as a result of thermal motion due to insufficient energy of their binding with atoms. As a result, at temperatures above absolute zero, they still have a certain electrical conductivity under the influence of external voltage. Their conductivity coefficient is quite low (the same silicon conducts an electric current millions of times worse than copper), but they still conduct some kind of current, albeit insignificant. Such substances are called semiconductors.
As it turned out as a result of research, electrical conductivity in semiconductors, however, is due not only to the movement of free electrons (the so-called n-conductivity due to the directional movement of negatively charged particles). There is also a second mechanism of electrical conductivity, which is quite unusual. When an electron is released from the crystal lattice of a semiconductor due to thermal motion, a so-called hole is formed in its place - a positively charged cell of the crystal structure, which can at any time be occupied by a negatively charged electron that has jumped into it from the outer orbit of a neighboring atom, where, in turn , a new positively charged hole is formed. Such a process can continue for an arbitrarily long time, and it will look from the side (on a macroscopic scale) that the electric current under external voltage is not due to the movement of electrons (which just jump from the outer orbit of one atom to the outer orbit of a neighboring atom), but directed migration of a positively charged hole (electron deficit) towards the negative pole of the applied potential difference. As a result, a second type of conductivity is also observed in semiconductors (the so-called hole, or p-conductivity), due, of course, also to the movement of negatively charged electrons, but from the point of view of the macroscopic properties of the substance, it is represented by a directed current of positively charged holes to the negative pole.
The hole conduction phenomenon is most easily illustrated with the example of a traffic jam. As the car stuck in it moves forward, free space is formed in its place, which is immediately occupied by the next car, the place of which is immediately taken by the third car, etc. This process can be imagined in two ways: you can describe the rare advance of individual cars from among those standing in a long traffic jam; it is easier, however, to characterize the situation from the point of view of episodic movement in the opposite direction of a few voids between cars stuck in a traffic jam. It is guided by a similar analogy that physicists talk about hole conduction, conditionally taking it for granted that the electric current is conducted not due to the movement of numerous, but rarely moving away from the place of negatively charged electrons, but due to the movement in the opposite direction of positively charged voids in the outer orbits of semiconductor atoms, which they agreed to call holes. Thus, the dualism of electron-hole conduction is purely arbitrary, since from a physical point of view, the current in semiconductors is in any case due exclusively to the directional motion of electrons.
Semiconductors have found wide practical application in modern radio electronics and computer technologies precisely because their conductive properties are easily and accurately controlled by changing external conditions.
electronic theory of conduction
The electrical conductivity of solids is due to the collective directional motion of free electrons
PART A. Multiple Choice Tests
1. Distribution of electrons by energy levels in a lithium atom:
2. The number of electrons on the outer electron layer of alkali metal atoms:
3. The type of chemical bond in a simple sodium substance:
4. A simple substance with the most pronounced metallic properties:
5. The radius of the atoms of the elements of the main subgroup with an increase in the nuclear charge:
6. The calcium atom differs from the calcium ion:
7. Reacts most vigorously with water:
8.Does not interact with hydrochloric acid:
9. Aluminum hydroxide interacts with a substance, the formula of which is:
10. A row in which all substances react with iron:
PART B. Tasks with a free answer
11. Suggest three ways to obtain calcium hydroxide. Confirm the answer with the reaction equations.
12. Determine the substances X, Y, Z, write down their chemical formulas.
13. How, using any reagents (substances) and lithium, to get oxide, base, salt? Write the equations of reactions in molecular form.
14. Arrange the metals: aluminum, lead, gold, copper in order of increasing relative conductivity (Fig. 2).
