Hydrogen compounds of nonmetals. Regularities in changing their properties in connection with the position chemical elements in the periodic system of D. I. Mendeleev.
hydrides. In compounds with non-metals, hydrogen exhibits an oxidation state of +1. Since the ionization energy of hydrogen is very high, its chemical bond with non-metals is not ionic, but polar-covalent. The most electronegative p-elements on the right side of the periods, such as sulfur and chlorine, react with hydrogen to form covalent hydrides, which have acid properties and the strength of these acids increases as the size of the atom of the non-metal attached to the hydrogen increases. The exceptions are methane CH 4 , which is a neutral compound, and ammonia NH 3 , which has basic properties. Hydrogen compounds of non-metals are highly soluble in water and form acids with the same formulas.
The more electronegative p-elements, such as aluminum, silicon, and phosphorus, do not react with hydrogen when heated.
Ticket number 14.
Higher oxides of chemical elements of the third period. Patterns in the change of their properties in connection with the position of chemical elements in the periodic system of D. I. Mendeleev. Characteristic chemical properties of oxides: basic, amphoteric, acidic.
The reactivity of the elements with oxygen generally decreases as one moves to the right along each period. For example, in the 3rd period, two s-metals, sodium and magnesium, and two p-elements, aluminum and phosphorus, react violently with oxygen, forming oxides. In the same period, the elements silicon and sulfur are only able to slowly react with oxygen. Chlorine and argon, located at the right end of the period, do not react with oxygen at all.
Electropositive s-metals form ionic oxides, such as sodium oxide Na 2 O and magnesium oxide MgO. Oxides of elements located in the middle and right parts of the period are predominantly covalent compounds, such as oxides of nitrogen and sulfur.
The acid-base character of the oxides also changes from basic in the oxides of the elements of the left part of the period to amphoteric in the oxides of the elements of the middle part of the period and further to acidic in the oxides of the elements of the right part of the period. For example, s-metals usually form oxides, which dissolve in water to form alkaline solutions:
Molecular oxides of p-elements, such as carbon dioxide and sulfur trioxide, usually have acidic properties. A regular change in the basic properties with the transition to acidic properties is clearly manifested in oxides of elements of the 3rd period.
Ticket number 15.
Acids, their classification and chemical properties based on the concept of electrolytic dissociation. Features of the properties of concentrated sulfuric acid on the example of interaction with copper.
An acid is a complex substance, during the dissociation of which only one type of cations is formed - hydrogen ions.
Classification of acids.
Hydrochloric acid - water solution hydrogen chloride gas in water.
Chemical properties. Acids change the color of indicators: litmus turns red, methyl orange turns yellow.
When reacting with bases, salt and water are formed (neutralization reaction). Both water-soluble and water-insoluble bases react:
When reacting with basic oxides are formed with:
acids react with metals, located in series of voltages to hydrogen, while gaseous hydrogen is released and a salt is formed:
Strong acids react with salts of weak acids, displacing weak acids from their salts:
Getting acids. Many acids can be obtained by the reaction acid oxides with water:
concentrated sulfuric acid at ordinary temperature does not act on many metals. For this reason, for example, anhydrous sulfuric acid, unlike its solutions, can be stored in iron containers.
But concentrated sulfuric acid acts on almost all metals when heated. In this case, salts of sulfuric acid are formed, but hydrogen is not released, but other substances are obtained, for example, sulfur dioxide.
So, when concentrated sulfuric acid is heated with copper, sulfuric acid first oxidizes copper to copper oxide, while itself is reduced to sulfurous acid, which immediately decomposes into sulfur dioxide and water:
The resulting copper oxide reacts with excess sulfuric acid to form salt and water:
Thus, copper oxide is an intermediate in this reaction. Adding these equations, we get the final reaction equation, which includes only the initial and final substances:
1) (2 points). Atomic nuclei were discovered:
A.D. Mendeleev. W. J. Thomson.
B.E. Rutherford. G.D.Chedwig.
2) (2 points). The period number in the Periodic System is determined by:
BUT). The charge of the nucleus of an atom.
B). The number of electrons in the outer layer of an atom.
AT). number electronic layers in the atom.
G). The number of electrons in an atom.
3*) (2 points). The shape of the electron orbitals is characterized by:
BUT). The main thing quantum number.
B). Magnetic quantum number.
AT). Orbital quantum number.
G). Spin quantum number.
4) (2 points). A pair of elements that have a similar structure of the outer and pre-outer energy levels:
BUT). S and Cl. B). Be and B. B). Kr and Xe. G). Mo and Se.
5) (2 points). p-Element is:
BUT). Scandium. B). Barium. AT). Arsenic. G). Helium.
6) (2 points). The electronic configuration …3d104s2 corresponds to the element:
A). calcium. B). Krypton. AT). Cadmium. G). Zinc.
7) (2 points). amphoteric hydroxide is a substance whose formula is:
BUT). Zn(OH)2. B). Mg(OH)2. AT). Ca(OH)2 . G). Cr(OH)2.
8) (2 points). A number of elements, arranged in order of increasing metallic properties:
BUT). Mg-Ca-Zn. B). Al-Mg-Ca. AT). Sr-Rb-K. D).Ge-Si-Sb.
9) (2 points). The element E with the electronic formula 1s22s22p63s23p63d104s24p1 forms the highest oxide corresponding to the formula:
BUT). E2O. B). E2O3. AT). EO2. G). EO3.
10) (2 points) An isotope of iron, the nucleus of which contains 22 neutrons, is denoted by:
BUT). 40/20Ca. B). 42/20Ca. AT). 44/20Ca. G). 48/20Ca.
11) (9 points). Set a match.
A).1s22s22p63s23p1 1). Aluminum.
B).1s22s22p63s2 2). Potassium.
C).1s22s22p63s23p63d104s24p4 3). Selenium.
D).1s22s22p63s23p64s1 4). Magnesium.
Formula of the highest oxide.
1.E2O 2.E2O3 3.EO 4.EO3.
Higher hydroxide formula
1.EON 2. E(OH)2 3. E(OH)3 4.H2EO4.
12) (3 points). Based on the position in the Periodic system, arrange the elements: Germanium, Arsenic, Sulfur, Phosphorus - in descending order of oxidizing properties. Explain your answer.
13) (6 points). How and why do metallic properties change in the Periodic Table?
BUT). Within the period.
B). Within the main subgroup.
14).(7 points). Write the electronic formula of the element with the serial number 30 in the Periodic system. Make a conclusion about whether this element belongs to metals or non-metals. Write down the formulas of its higher oxide and hydroxide, indicate their nature.
15) (5 points). What chemical properties are characteristic of the oxide of the element of the 3rd period, the main subgroup of group VI of the Periodic system? Support your answer by writing the reaction equations.
A1. Chemical signnitrogen element:
BUT)
Al b) N c) Na
d) O
A2. Element name
with sign Fe:
A) copper
b) Iron c) Gold d) Aluminum
A3. complex substance
- This …
A) carbon dioxide b) copper c)
hydrogen d) oxygen
A4. The relative molecular weight is the largest in a substance
With formula:
A) H2S b) SO2 c) K2S d) CuS
A5.
Element of the third period of the main subgroup of group II
Periodic system of chemical elements D.I. Mendeleev is...
A) aluminum b) beryllium c) magnesium d) calcium
A6. An isotope whose nucleus contains 8 protons and
8 neutrons:
A) 168O b) 178O c) 188O d) 198O
A7. An atom of a chemical element whose electron shell contains
16 electrons:
A) Oxygen b) Sulfur
c) Chlorine
d) sodium
A8. Two electron layers (energy levels) contains an atom:
A) Bora
b) Potassium c) Aluminum d) Magnesium
A9. A pair of chemical elements that have an external energy level
4 electrons each:
A) P and C b) Si and Ca c) N and P d) C and Si
A11. Information about
number of energy (electronic) levels
The element atom gives:
A) period number b) group number c)
serial number d) relative atomic mass
A10. Least electronegative
element (of the following):
A) nitrogen
b) Hydrogen c) Chlorine d) Phosphorus
A12.Chemical
element having 20e;20r11;20n01
A) Mg
b) Na c) Be d) Ca
IN 1. atom or ion
having the following distribution of electrons over energy levels 2e8e:
A) Ne
b) Ca+2 c) Mg+2 d) Na+
IN 2. Select
chemical elements arranged in order of decreasing metallic properties:
A) Li, F, Na, O b) Li, Na, O, F
c) F, Na, O, Li d) F, O, Na, Li
IN 3. potassium ions and
chlorine have:
A) the same nuclear charge
B) the same relative
molecular weight
B) the same total number
electrons
D) the same number of electrons per
outer energy level
C1. Write down the schemes
the formation of compounds consisting of atoms of chemical elements:
BUT)
hydrogen and fluorine b) magnesium and chlorine
Determine the type
chemical bond in them
C2. You write
compounds with a covalent polar bond: O2, Li, H2Se, K2O, BaCl2,
Fe, J2, FeS, HJ, SO3,
S, ZnO
relate? Why?
2) Write chemical formulas higher oxides of the elements Mg and S. Which oxides (basic, acidic or amphoteric) do they belong to? Why?
3) Write the chemical formulas of the higher oxides of the elements Ca and Cl. Which oxides (basic, acidic or amphoteric) do they belong to? Why?
4) Write the chemical formulas of the higher oxides of elements K and N. Which oxides (basic, acidic or amphoteric) do they belong to? Why?
5) Write the chemical formulas of the higher oxides of the elements Si and Li. Which oxides (basic, acidic or amphoteric) do they belong to? Why?
Option 2. PART A. Test tasks with a choice of answers. ^ 1. (2 points). Electronic formula of an atom of an element of the main subgroup of group IV, 3rd periodPeriodic system: A. 1s22s22p2. B. 1s22s22p63s23p4. B. 1s22s22p63s23p2. G. 1s22s22p63s23p6. ^ 2. (2 points). Supreme Oxide and hydroxide of an element of the main subgroup of group V of the Periodic system correspond to the general formulas: A. E02 and H2EO3. B. E03 and H2EO4. B. E2O5 and NEO3. D. E2O7 and NET4. ^ 3. (2 points). Oxidizing properties weaken in a number of elements: A. P-N-O-F. B. C1-S-P-As. B. Br-C1-F-I. G. V-C-N-P. 4. (2 points). The electronic formula Is22s22p63s2 corresponds to a particle whose designation is: A.S0. B.A13+. B.S4+. G, Si0. 5. (2 points). A covalent polar bond is formed in a compound whose formula is: A. PH3. B. Nal. B. 02. D. S02 6. (2 points). Valency and oxidation state of nitrogen in nitric acid respectively equal: A. Five and +5. B. Four and +5. B. Three and +5. D. Three and + 3. 7. (2 points). An atomic crystal lattice has: A. Ozone. B. Diamond. B. Oxygen. G. Hydrogen. 8. (2 points). Acid properties in a series of compounds whose formulas are N2O5 - P2O5 - As2O5: ^ A. Change periodically. B. Do not change. B. Strengthen. D. Weaken. 9. (2 points). The simple substance sulfur interacts with each of the substances of the series: A. HC1, Na, 02. B. K, Zn, Na2SO4. B. Mg, 02, H2. G. A1, H20, 02.10. (2 points). The C-4 → C+4 transformation scheme corresponds to the equation: A. CH4 + O2 = C + 2H2O. B. C + O2 = CO2. B. CH4 + 2O2 = CO2 + 2H2O. ^ G. CO2 + C = 2CO. PART B. Tasks with a free answer. 11. (10 points). Write the reaction equations that can be used to carry out the following transformations: NH3 ← N2 → NO → NO2 → HNO3. Specify types chemical reactions. 12. (4 points). Which of the gases will occupy a larger volume (n.a.): 100 g of carbon dioxide or 5 g of hydrogen? Support your answer with calculations. ^ 13. (4 points). In what connection covalent bond will be more polar: in methane or silane? Give a reasoned answer. 14. (6 points). Arrange the coefficients in the reaction scheme P + H2SO4 (KOH.) → H3PO4 + SO2 + H2O using the electron balance method. Specify the oxidizing agent and reducing agent. 15. (6 points). In the acid obtained by dissolving 11.2 liters of gaseous hydrogen chloride (n.a.) in water, placed 13 g of zinc. Calculate the volume of gas released in this case (n. c.).
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Arrangement of elements in periodic table in accordance with their atomic number and external electronic configuration leads to the manifestation of two important regularities in chemical properties ax intransitive elements and their compounds:
1. Elements with similar chemical properties are divided into groups.
For example, all alkali metals are in group I and all halogens are in group VII.
2. The most electropositive elements, and therefore the most reactive metals, are located in the lower left corner of the periodic table. The electropositivity of the elements gradually decreases as one moves from bottom to top along each group, and as one moves from left to right along each period.
The most electronegative elements, and therefore the most reactive non-metals, are located in the upper right corner of the periodic table. The electronegativity of the elements increases when moving along each period in the direction from group I to group VII, but decreases when moving from top to bottom along each group.
Table 11.11. Patterns in the formation of compounds by elements of the 2nd and 3rd periods
Table 11.12. Examples of p-element ligands in d-element complex ions
The electronegativity or electropositivity of elements is directly related to the types of chemical reactions that the elements are capable of entering into, and hence to the types of compounds formed by the elements. s-Metals are characterized by the ability to readily form cations and thus ionic compounds (see Table 11.11). -Elements located closer to the center of the periodic table are characterized by the ability to form only covalent compounds. More electronegative p-elements, located closer to the right edge of the periodic
Rice. 11.11. Periodic changes in the oxidation states of non-transition elements
Rice. 11.12. Periodic changes in the oxidation states of d-elements of the first, second and third transition series (i.e., the 4th, 5th and 6th periods, respectively).
Table 11.13. Characteristic valencies of the elements of the 3rd period
tables are capable of forming both covalent and ionic compounds. The noble gases, which have a stable electronic configuration, form relatively few compounds.
As can be seen from fig. 11.3, d-elements are located in the periodic table between groups II and III. They are all metals, but less electropositive and therefore more electronegative than s-metals (alkali and alkaline earth metals). As a consequence, their compounds, such as oxides and chlorides, are usually either ionic with a high degree of covalent character or covalent. Together with p-elements located closer to the central part of the periodic table, they often form compounds of a high molecular type or compounds with a layered or chain structure.
d-Elements have the ability to form both cationic and anionic complex ions, which is not typical for s-metals. p-Elements are often included in the composition of ligands in both cationic and anionic complexes (Table 11.12).
Valences (see Chap. 4) of intransitive elements also show periodic changes. From Table. 11.13 it can be seen that all elements of the 3rd period show valences that numerically coincide with the group number of the element. In addition, all elements of groups IV-VII show valencies equal to the difference between the number 8 and their group number.
The maximum oxidation states of the elements also show periodic changes (Figures 11.11 and 11.12). As a rule, they increase when moving from left to right along the period and reach maximum values in groups V-VII. It is also noteworthy that the elements with higher degrees oxidations reveal, in addition to them, many other oxidation states. For example, chlorine can exist in states with all oxidation states from -1 to
In all three rows of transition metals (-elements), the maximum oxidation state is reached in the middle part of the row (Fig. 11.12). -Elements with higher oxidation states, in addition to them, also have the maximum number of other oxidation states. For example, in the first row of transition metals, manganese exhibits five positive oxidation states from to
Frequency of redox properties
The redox properties of the elements also show periodic changes. The pattern of these changes is as follows: the elements occupying the left side of the periodic table, i.e., alkali and alkaline earth metals (-metals), are strong reducing agents. Then, as you move to the right along each period, the elements become progressively weaker reducing agents and increasingly stronger oxidizing agents. Finally, when moving to group VII, the elements become strong oxidizing agents. Let us now consider this pattern in somewhat more detail.
The reducing properties of -metals are characterized by:
low ionization energy,
low electron affinity
low electronegativity,
high "electropositivity" (qualitative term - see previous footnote),
negative standard redox potential.
1. Reaction with air or oxygen
2. Reaction with chlorine
Reaction with dilute acids
These are all examples of the reducing ability of s-metals, since in each case the metal easily donates electrons:
A detailed discussion of the chemistry of alkali and alkaline earth metals is carried out in ch. thirteen.
The oxidizing properties of the elements of group VII are characterized by: high ionization energy, high electron affinity, high electronegativity, low "electropositivity",
positive standard redox potential.
Chlorine is a strong oxidizing agent. It reacts violently with hydrogen in sunlight to form hydrogen chloride. In contrast, it does not react with other oxidizing agents, such as oxygen or dilute acids. A detailed discussion of the chemistry of chlorine and other halogens is given in Chap. sixteen.
Properties of elements from the middle part of the periods. Group VII elements are p-elements, which are located on the right side of the periodic table. p-Elements located closer to the middle part of the periods show weak reducing and (or) weak oxidizing properties. For example, silicon belonging to group IV reacts slowly with oxygen, forming an oxide
Nitrogen belonging to group V can act both as a weak reducing agent and as a weak oxidizing agent. For example, it behaves like a weak reducing agent when reacting with oxygen:
In contrast, in the reaction with hydrogen, nitrogen behaves as a weak oxidizing agent:
Transition elements have the properties of weak reducing agents. For example, red-hot iron reacts with water vapor to form hydrogen:
Periodicity of compound properties
In the formation, structure, as well as the physical and chemical properties of compounds, periodic patterns of change are also found. We will trace these regularities on the example of oxides, hydrides, hydroxides and halides.
Oxides. The reactivity of the elements with oxygen generally decreases as one moves to the right along each period. For example, in the 3rd period, two s-metals, sodium and magnesium, and two p-elements, aluminum and phosphorus, react violently with oxygen, forming oxides. In the same period, the elements silicon and sulfur are only able to slowly react with oxygen. Chlorine and argon, located at the right end of the period, do not react with oxygen at all.
Electropositive s-metals form ionic oxides, such as sodium oxide and magnesium oxide. Oxides of elements located in the middle and right parts of the period are predominantly covalent compounds, such as oxides of nitrogen and sulfur.
The acid-base character of the oxides also changes from basic in the oxides of the elements of the left part of the period to amphoteric in the oxides of the elements of the middle part of the period and further to acidic in the oxides of the elements of the right part of the period. For example, s-metals usually form oxides, which dissolve in water to form alkaline solutions:
Molecular oxides of p-elements, such as carbon dioxide and sulfur trioxide, usually have acidic properties. A regular change in the basic properties with the transition to acidic properties is clearly manifested in oxides of elements of the 3rd period.
Oxides of d-elements are usually insoluble in water and have basic properties, although one or two of them. for example, zinc oxide, exhibit amphoteric properties (see Chap. 14).
A detailed discussion of the chemistry of oxides is carried out in Sec. 15.4.
Hydrides. In the formation, structure, and properties of hydrides, regularities similar to those described above for oxides, although not completely identical with them, can be traced.
s-Metals, such as sodium and magnesium, tend to react violently when heated with dry hydrogen to form ionic hydrides. These ionic hydrides have basic properties. The most electronegative -elements on the right side of the periods, such as sulfur and chlorine, react with hydrogen to form covalent hydrides, which have acidic properties. The exceptions are methane, which is a neutral compound, and ammonia, which has basic properties.
The more electronegative α-elements, such as aluminum, silicon, and phosphorus, do not react with hydrogen when heated.
Transition d-metals in a heated state react with hydrogen, forming non-stoichiometric hydrides.
The preparation, structure, and properties of hydrides are described in detail in Chap. 12.
Hydroxides. The hydroxides of the most electropositive elements, such as sodium and calcium, are ionic compounds with strongly basic properties. In contrast, the strongly electronegative element chlorine forms an acidic hydroxide, hypochlorous acid. In this compound, the bond between the chlorine and oxygen atoms is covalent. Hydroxides of some less electronegative elements have amphoteric properties. Often they are unstable and form oxides.
Table 11.14. Properties of chlorides of elements of the 3rd period
Halides. Halides show periodic changes in properties similar to those described above for oxides, hydrides and hydroxides. When moving to the right along the period from the most electropositive to the most electronegative elements, a decrease in the boiling point and melting point is observed (Table 11.14). Thus, the chlorides of the first three elements in the 3rd period under normal conditions are solids, the chlorides of the next three elements are liquids, and chlorine is a gaseous substance.
The ionic character of chlorides decreases when moving to the right along the period, while the covalent character, on the contrary, increases.
The s-element halides are usually salts of strong acids and strong bases. They dissolve in water to form neutral solutions. Chlorides of p- and d-elements are characterized by the ability to react with water, forming acidic solutions. For example,
The reactions of d-element chlorides in water are described in Chap. 14, and the chemistry of the halides is discussed in more detail in Chap. sixteen.
Diagonal relationships between elements
It was noted earlier that the electropositivity of elements generally decreases as one moves to the right along a period, but increases as one moves down a group. This leads to the so-called diagonal ratios in the periodic table. Each diagonal relationship links a pair of elements with similar chemical properties. The most important pairs of elements linked by diagonal ratios are lithium and magnesium, beryllium and aluminum, boron and silicon.
The presence of diagonal relationships is explained by the fact that the decrease in electropositivity when moving to each next element to the right along the period is compensated by an increase in electropositivity when moving down the group to the next element. A more detailed discussion of diagonal relations is carried out in Chap. thirteen.
anomalies
Head elements in main subgroups. Elements of the 2nd period, "heading" groups I-VII (the main subgroups in the short period form of the periodic table. - Trans.), are sometimes called head elements. They are of interest due to the fact that some properties of these elements and their compounds differ significantly from similar properties characteristic of other elements of the corresponding groups. These anomalous properties can be attributed to the smaller size of the lead element atoms and their higher electronegativity and ionization energy. For example, lithium and beryllium halides exhibit a more covalent character than other metal halides from the respective groups. Lithium, unlike other alkali metals, does not form a solid bicarbonate. While other alkali metal nitrates decompose on heating to form the corresponding nitrites and oxygen, lithium nitrate decomposes to form lithium oxide, oxygen, and nitrogen dioxide. Finally, unlike hydroxides of other alkali metals, lithium hydroxide is thermally unstable. The anomalous properties of lithium and other lead elements are discussed in detail in Chap. 13, 14 and 16.
So let's do it again!
1. Elements in the modern periodic table are arranged in ascending order of their atomic number.
2. Elements of the same period have the same electron core, with the same configuration as the noble gas that completed the previous period.
3. Elements of the same group have the same external electronic configuration.
4. All -elements (with the exception of hydrogen and helium), as well as d- and -elements, belong to metals.
5. Hydrogen and helium are non-metals. All other non-metals belong to p-elements.
6. When moving from left to right along the period, the metallic properties of the elements weaken, and when moving from top to bottom along the group, the metallic properties of the elements increase.
7. Physical properties elements (melting and boiling points, enthalpies of melting and evaporation, density) when moving from left to right along the period, they first increase, and then, after reaching a maximum in the middle part of the period, decrease.
8. The atomic and ionic radii of the elements decrease when moving from left to right along the period, and increase when moving from top to bottom along the group.
9. The first ionization energy of the elements increases when moving from left to right along the period, and decreases when moving from top to bottom along the group.
10. The electronegativity of the elements within each period increases, reaching a maximum for halogens, and decreases as you move from top to bottom in the group.
11. The most electropositive, and therefore the most reactive
capable (active) metals are located in the lower left corner of the periodic table.
12. The most electronegative elements are located in the upper right corner of the periodic table.
13. s-Elements, as a rule, show valences that match their group number.
14. p-Elements have main valences equal to their group number, as well as equal differences between the number 8 and their group number.
15. d-Elements show many different valencies and oxidation states.
16. The restorative properties of the elements weaken when moving from top to bottom along the group.
17. The reactivity of elements with respect to oxygen decreases when moving from top to bottom along the group.
18. The ionic character of oxides decreases when moving from left to right along the period, and the covalent character increases.
19. Oxides, hydrides, hydroxides and halides of elements show the same periodicity in changing properties.
20. Lithium and magnesium have similar chemical properties and thus show a diagonal relationship between them.
21. The head elements leading the main groups have anomalous properties in relation to the rest of the elements of their groups.
