PART 1
1. Metals (M) are located in groups I-III, or in the lower part of groups IV-VI. B groups are made up of metals only.
2. Metal atoms have 1-3 electrons in the outer electron layer and a relatively large atomic radius. Metal atoms tend to lose outer electrons.
3. Simple substances- metals consist of elements connected by a metallic chemical bond, which can be represented by a general diagram:
4. All M are solids, except Hg. The softest metals are group IA, the hardest is Cr.
5. M have thermal and electrical conductivity and have a metallic sheen.
6. Tin has the property of forming two simple substances- white and gray, i.e. the property of allotropy.
7. Complete the table “Properties and applications of some metals.”
PART 2
1. Choose the names of simple substances - metals. Using the letters corresponding to the correct answers, you will form the name of the metal, which means “stone” in Greek: lithium.
2) magnesium L
3) calcium I
5) copper T
7) gold I
8) mercury J
2. The following statements characterizing metals are incorrect:
5) non-plastic and non-malleable
3. Select the four most electrically conductive metals (arrange the numbers in descending order of electrical 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 diagrams of the formation of metallic chemical bonds for substances with the formulas:
5. Analyze the drawing “Metal crystal lattice”.
Draw 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 move freely from one formed ion to another, connecting the ionic core of the metal into a giant molecule. The high thermal conductivity and electrical conductivity of metals are due to the presence in their crystal lattices of mobile electrons moving under the influence of an electric field. Most metals are ductile due to the displacement of layers of metal atoms without breaking the bonds between them.
6. Fill out the “Metals” table. Find 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; not only mercury itself was used, but also its alloy, cinnabar.
2) It is very toxic, evaporates at room temperature, and poisons humans if inhaled. Accumulating in the body, it affects internal organs, respiratory tracts, hematopoietic organs and the brain.
3) Mercury is used very widely. 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 energy). This element is used in the manufacture of fluorescent lamps, quartz lamps, pressure gauges, thermometers and other scientific instruments.
Conductivity
Superconductivity theory
When crystal lattices of solids are formed from atoms of various substances, valence electrons located in the outer orbits of the atoms interact with each other in different ways and, as a result, behave differently (see band
solid state superconductivity theory and theory
molecular orbitals). Thus, the freedom of valence electrons to move within a substance is determined by its molecular-crystalline structure. In general, according to their electrically conductive properties, all substances can (with some degree of convention) be divided 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 “common property” of the atoms of the crystal lattice (see.
chemical bonds and electronic theory of conductivity).
If you apply an electrical voltage to such a substance (for example, connect the poles of a battery to its two ends), the electrons will begin to move unhindered in an orderly manner towards the south pole of the potential difference, thereby creating an electric current. Conducting substances of this kind are usually called conductors. The most common conductors in technology are, of course, metals, primarily copper and aluminum, which have minimal 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 that have good electrical conductivity, such as salt, alkaline and acidic 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 caused by 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 there are so many different salts dissolved, which decompose when dissolved into negatively charged cations and positively charged anions, that water (even fresh water) 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 (particularly glass, porcelain, plastics), electrons are tightly bound to atoms or molecules and
are not capable of free movement under the influence of externally applied electrical voltage. Such 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 also form complex and very strong interweavings. The easiest way to imagine the structure of the polymer is in the form of a plate of long and thin noodles entangled and stuck together. In such materials, electrons are tightly bound to their ultra-long molecules and are not able to leave them under the influence of external voltage. 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 technological civilization, which uses electricity as the main means of transmitting energy over distances. Electricity is carried through conductors from power plants to our homes and to various industrial enterprises, and insulators ensure our safety by protecting us from the harmful 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 them are silicon and germanium). In the crystal lattices of these substances, all valence electrons, at first glance, are connected by chemical bonds and, it would seem, there should be no free electrons left to ensure electrical conductivity. However, in reality the situation looks somewhat different, since some 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 (silicon conducts electric current millions of times worse than copper), but they still conduct some 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 - and a very unusual one. 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 moment 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 as long as desired, and from the outside (on a macroscopic scale) everything will look like the electric current under external voltage is caused not by the movement of electrons (which just jump from the outer orbit of one atom to the outer orbit of a neighboring atom), but by a directed migration of a positively charged hole (electron deficiency) towards the negative pole of the applied potential difference. As a result, a second type of conductivity is observed in semiconductors (the so-called hole or p-conductivity), which is, of course, also caused by the movement of negatively charged electrons, but from the point of view of the macroscopic properties of the substance, it appears to be a directed current of positively charged holes towards the negative pole.
The phenomenon of hole conduction is most easily illustrated using the example of a traffic jam. As the car stuck in it moves forward, a free space is formed in its place, which is immediately occupied by the next car, whose place is immediately occupied by a third car, etc. This process can be imagined in two ways: you can describe the rare movement 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 the episodic movement in the opposite direction of the few voids between the cars stuck in the traffic jam. It is guided by this analogy that physicists talk about hole conductivity, conventionally taking it for granted that electric current is conducted not due to the movement of numerous, but rarely moving 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 conductivity is purely conditional, since from a physical point of view, the current in semiconductors is in any case determined exclusively by the directional movement of electrons.
Semiconductors have found wide practical application in modern radio electronics and computer technology precisely due to the fact that their conductive properties are easily and accurately controlled by changing external conditions.
electronic conductivity theory
The electrical conductivity of solids is due to the collective directed movement of free electrons
Option 1.
1. Distribution of electrons by energy levels in a magnesium atom:
G. 2e, 8e, 2e.
A.1.
3. Type of chemical bond in the simple substance lithium:
G. Metal.
G. Strontium.
5. Radius of atoms of elements of the 3rd period with increasing nuclear charge from alkali metal to halogen:
D. Decreases.
6. An aluminum atom differs from an aluminum ion:
B. The radius of the particle.
A. Potassium.
8 . Does not react with dilute sulfuric acid:
B. Platinum.
9. Beryllium hydroxide interacts with a substance whose formula is:
A. CON (rr).
10. A series in which all substances react with zinc:
A. HCl, NaOH, H2SO4.
11.Suggest three ways to obtain potassium hydroxide. Confirm your answer with reaction equations.
2K + 2H2O = 2KOH + H2
K2O + H2O = 2KOH
K2CO3 + Ca(OH)2 = CaCO3↓ + 2KOH
X CuO
Y CuSO4
Z Cu(OH)2
13. How, using any reagents (substances) and barium, to obtain an oxide, base, salt? Write down reaction equations in molecular form.
13. 2Ba + O2 = 2BaO
Ba + 2H2O = Ba(OH)2 + H2
Ba + Cl2 = BaCl2
14. Arrange the metals: iron, tin, tungsten, lead in order of increasing relative hardness (Fig. 1).
lead – tin – iron – tungsten
15. Calculate the mass of metal that can be obtained from 144 g of iron (II) oxide.
n (FeO) = 144g/ 72g/mol = 2 mol
n(Fe) = 2 mol
m (Fe) = 2mol*56g/mol = 112g
Option 2.
PART A. Multiple Choice Tests
1. Distribution of electrons by energy levels in a lithium atom:
B. 2e, 1e.
2. The number of electrons in the outer electron layer of alkali metal atoms:
A. 1.
3. Type of chemical bond in the simple substance sodium:
G. Metal.
4. A simple substance with the most pronounced metallic properties:
G. Indium.
B. Increases.
6. A calcium atom differs from a calcium ion:
B. The number of electrons at the external energy level.
7. Reacts most vigorously with water:
A. Barium.
B. Silver.
9. Aluminum hydroxide interacts with a substance whose formula is:
B. NaOH(p-p).
10. A series in which all substances react with iron:
B. Cl2, CuC12, HC1.
PART B. Free-response questions
11. Suggest three ways to obtain calcium hydroxide. Confirm your answer with reaction equations.
Ca + 2H2O = Ca(OH)2 + H2
CaO + H2O = Ca(OH)2
CaCl2 + 2KOH = Ca(OH)2 + 2KCl
12. Identify substances X, Y, Z, write down their chemical formulas.
X ZnO
Y ZnCl2
Z Zn(OH)2
13. How, using any reagents (substances) and lithium, to obtain an oxide, base, salt? Write down reaction equations in molecular form.
4Li + O2 = 2Li2O
2Li + 2H2O = 2LiOH + H2
2Li + Cl2 = 2LiCl
14. Arrange the metals: aluminum, lead, gold, copper in order of increasing relative electrical conductivity (Fig. 2).
Lead, aluminum, gold, copper.
15. Calculate the mass of metal that can be obtained from 80 g of iron (III) oxide.
n(Fe2O3) = 80g/160g/mol = 0.5mol
n (Fe) = 2n (Fe2O3) = 1 mol
m (Fe) = 1mol*56g/mol = 56g
Option 3.
PART A. Multiple Choice Tests
1. Distribution of electrons by energy levels in the sodium atom:
B. 2e, 8e, 1e.
2. Number of the period in the Periodic Table of D.I. Mendeleev, in which there are no chemical metal elements:
A. 1.
3. Type of chemical bond in the simple substance calcium:
G. Metal.
4. A simple substance with the most pronounced metallic properties:
G. Sodium.
5. Radius of atoms of elements of the 2nd period with increasing nuclear charge from alkali metal to halogen:
D. Decreases.
6. A magnesium atom differs from a magnesium ion:
B. Charge of the particle.
7. Reacts most vigorously with water:
G. Rubidium.
8. Does not interact with dilute sulfuric acid:
G. Mercury.
9. Beryllium hydroxide does not interact with a substance whose formula is:
B. NaCl (solution)
10. A series in which all substances react with calcium:
B. C12, H2O, H2SO4.
PART B. Free-response questions
11. Suggest three ways to obtain iron (III) sulfate. Confirm your answer with reaction equations.
Fe + H2SO4 = FeSO4 + H2
FeO + H2SO4 = FeSO4 + H2O
Fe + CuSO4 = FeSO4 + Cu
12. Identify substances X, Y, Z, write down their chemical formulas.
X Fe2O3
YFeCl3
Z Fe(OH)3
13. How, using any reagents (substances) and aluminum, to obtain an oxide, amphoteric hydroxide? Write down reaction equations in molecular form.
4Al + 3O2 = 2Al2O3
2Al + 6H2O = 2Al(OH)3 + 3H2
14. Arrange the metals: copper, gold, aluminum, lead in order of increasing density (Fig. 3).
aluminum, copper, lead, gold
15. Calculate the mass of metal obtained from 160 g of copper (II) oxide.
n(CuO) = 160g/80g/mol = 2mol
n (Cu) = n (CuO) = 2 mol
m (Cu) = 2mol*64g/mol = 128g
Option 4.
PART A. Multiple Choice Tests
1. Distribution of electrons by energy levels in an aluminum atom:
B. 2e, 8e, 3e.
2. Group number in the Periodic Table of D.I. Mendeleev, consisting only of chemical elements-metals:
B. II.
3. Type of chemical bond in the simple substance magnesium:
G. Metal.
4. A simple substance with the most pronounced metallic properties:
G. Rubidium.
5. Radius of atoms of elements of the main subgroup with increasing nuclear charge:
B. Increases.
6. The sodium atom and ion are different:
B. The radius of the particle.
7. Reacts most vigorously with water:
B. Potassium.
8. Does not interact with hydrochloric acid:
B. Copper.
9. Aluminum hydroxide does not interact with a substance whose formula is:
B. KNO3(p-p).
10. A series in which all substances react with magnesium:
B. C12, O2, HC1.
PART B. Free-response questions
11. Suggest three ways to obtain aluminum oxide. Confirm your answer with reaction equations.
2Al(OH)3 = Al2O3 + 3H2O
4Al + 3O2 = 2Al2O3
2Al + Cr2O3 = Al2O3 + 2Cr
12. Identify substances X, Y, Z, write down their chemical formulas.
XCaO
YCa(OH)2
ZCaCO3
13. How, using any reagents (substances), to obtain an oxide, base, salt from zinc? Write down reaction equations in molecular form.
2Zn + O2 = 2ZnO
Zn + 2H2O = Zn(OH)2 + H2
Zn + Cl2 = ZnCl2
14. Arrange the metals: aluminum, tungsten, tin, mercury in order of decreasing melting point (Fig. 4).
tungsten, aluminum, tin, mercury
15. Calculate the mass of metal that can be obtained by aluminothermy from 34 g of chromium (II) oxide.
n(CrO) = 34g/68g/mol = 0.5mol
n (Cr) = n (CrO) = 0.5 mol
m (Cr) = 0.5mol*52g/mol = 26g