DEFINITION
non-metals- chemical elements, the atoms of which accept electrons to complete the external energy level, forming negatively charged ions.
Electronic configuration of valence electrons of nonmetals in general view- ns 2 np 1−5 The exceptions are hydrogen (1s 1) and helium (1s 2), which are also considered as non-metals.
Nonmetals generally have a wide range of oxidation states in their compounds. The greater number of electrons in the external energy level compared to metals determines their greater ability to attach electrons and display high oxidative activity.
If you mentally draw a diagonal from beryllium to astatine in the Periodic system, then in the upper right corner of the table there will be non-metal elements. Among non-metals there is an s-element - hydrogen; p-elements boron; carbon, silicon; nitrogen, phosphorus, arsenic, oxygen, sulfur, selenium, tellurium, halogens and astatine. Group VIII elements are inert (noble) gases that have a fully completed external energy level and cannot be attributed to either metals or non-metals.
Non-metals have high values of electron affinity, electronegativity and redox potential.
Chemical properties of non-metals
The main chemical properties of non-metals (common to all) are:
- interaction with metals
2Na + Cl 2 \u003d 2NaCl
6Li + N 2 = 2Li 3 N
2Ca + O 2 \u003d 2CaO
- interaction with other non-metals
3H 2 + N 2 \u003d 2NH 3
H 2 + Br 2 \u003d 2HBr
4P + 5O 2 \u003d 2P 2 O 5
2F2 + O2 = 2OF2
S + 3F 2 \u003d SF 6,
C + 2Cl 2 = CCl 4
Each non-metal has specific chemical properties that are characteristic only for it, which are considered in detail when studying each non-metal separately.
Physical properties of non-metals
Fluorine, chlorine, oxygen, nitrogen, hydrogen and inert gases are gaseous substances, iodine, astatine, sulfur, selenium, tellurium, phosphorus, arsenic, carbon, silicon, boron are solid substances; bromine is a liquid.
Non-metals are found in the earth's crust (mostly oxygen and silicon - 76% of the mass of the earth's crust, as well as As, Se, I, Te, but in very small quantities), in the air (nitrogen and oxygen), as part of the plant mass (98 .5% - carbon, hydrogen, oxygen, sulfur, phosphorus and nitrogen), as well as in the basis of the mass of a person (97.6% - carbon, hydrogen, oxygen, sulfur, phosphorus and nitrogen). Hydrogen and helium are part of space objects, including the Sun. Most often in nature, non-metals occur in the form of compounds.
Obtaining non-metals
The variety of non-metals has given rise to a variety of ways to obtain them, so hydrogen is obtained as laboratory methods, for example, the interaction of metals with acids (1), and industrial ways, for example, the conversion of methane (2).
Zn + 2HCl \u003d ZnCl 2 + H 2
CH 4 + H 2 O \u003d CO + 3H 2 (temperature 900C)
The production of halogens is carried out mainly by the oxidation of hydrohalic acids:
MnO 2 + 4HCl \u003d MnCl 2 + Cl 2 + 2H 2 O
K 2 Cr 2 O 7 + 14HCl \u003d 3Cl 2 + 2KCl + 2CrCl 3 + 7H 2 O
2KMnO 4 + 16HCl \u003d 2 MnCl 2 + 5Cl 2 + 8H 2 O + 2KCl
To obtain oxygen, the reactions of thermal decomposition of complex substances are used:
2KMnO 4 \u003d K 2 MnO 4 + MnO 2 + O 2
4K 2 Cr 2 O 7 \u003d 4K 2 CrO 4 + 2Cr 2 O 3 + 3O 2
Sulfur is obtained by partial oxidation of hydrogen sulfide (1) or by the Wakenroder reaction (2):
H 2 S + O 2 \u003d 2S + 2H 2 O (1)
2H 2 S + SO 2 \u003d 3S ↓ + 2H 2 O (2)
To obtain nitrogen, the decomposition reaction of ammonium nitrite is used:
NaNO 2 +NH 4 Cl \u003d N 2 + NaCl + 2H 2 O
The main way to obtain phosphorus is from calcium phosphate:
Ca 3 (PO 4) 2 + 3SiO 2 + 5C \u003d 3CaSiO 3 + 5CO + 2P
Examples of problem solving
EXAMPLE 1
| Exercise | What volume of carbon monoxide (IV) (n.a.) will be obtained from the decomposition of limestone weighing 500 g containing 20% impurities? |
| Solution | Let's write the reaction equation: CaCO 3 \u003d CaO + CO 2 Find the mass of pure (without impurities) calcium carbonate: m(CaCO 3) = m(limestone) × (1-ω admixture) m (CaCO 3) \u003d 500 × (1-0.2) \u003d 400 g Find the amount of substance CaCO 3: v (CaCO 3) \u003d m (CaCO 3) / M (CaCO 3) v(CaCO 3) \u003d 400/ 100 \u003d 4 mol According to the equation v (CaCO 3) \u003d v (CO 2) \u003d 4 mol Then the amount of carbon dioxide USE. CHEMICAL PROPERTIES OF NON-METALSCHEMICAL PROPERTIES OF HYDROGEN 1. WITH METALS (Li, Na, K, Rb, Cs, Ca, Sr, Ba) → with alkali and alkaline earth metals, when heated, forms solid unstable substances hydrides, other metals do not react. 2K + H₂ = 2KH (potassium hydride) Ca + H₂ = CaH₂ 2. WITH NONMETALS with oxygen, halogens under normal conditions, when heated, it reacts with phosphorus, silicon and carbon, with nitrogen under pressure and a catalyst. 2Н₂ + O₂ = 2Н₂O Н₂ + Cl₂ = 2HCl 3Н₂ + N₂↔ 2NH₃ H₂ + S = H₂S 3. INTERACTION WITH WATER Does not react with water 4. INTERACTION WITH OXIDES Reduces oxides of metals (inactive) and non-metals to simple substances: CuO + H₂ = Cu + H₂O 2NO + 2H₂ = N₂ + 2H₂O SiO₂ + H₂ = Si + H₂O 5. INTERACTION WITH ACIDS Does not react with acids 6. INTERACTION WITH ALKALI Does not react with alkalis 7. INTERACTION WITH SALT Restores inactive metals from salts CuCl₂ + H₂ = Cu + 2HCl CHEMICAL PROPERTIES OF OXYGEN 1. INTERACTION WITH METALS With alkali metals under normal conditions - oxides and peroxides (lithium - oxide, sodium - peroxide, potassium, cesium, rubidium - superoxide 4Li + O2 = 2Li2O (oxide) 2Na + O2 = Na2O2 (peroxide) K+O2=KO2 (superoxide) With the rest of the metals of the main subgroups, under normal conditions, it forms oxides with an oxidation state equal to the group number 2 WITHa+O2=2WITHaO 4Al + O2 = 2Al2O3 1. INTERACTION WITH METALS With metals of secondary subgroups, under normal conditions and when heated, it forms oxides of various degrees of oxidation, and with iron, iron scaleFe3 O4 ( FeO∙ Fe2 O3) 3Fe + 2O2 = Fe3O4 4Cu + O₂ = 2Cu₂⁺¹O (red); 2Cu + O₂ = 2Cu⁺²O (black); 2Zn + O₂ = ZnO 4Cr + 3О2 = 2Cr2⁺³О3 forms oxides - often of an intermediate oxidation state C + O₂(ex)=CO₂; C+ O₂ (week) =CO S + O₂ = SO₂N₂ + O₂ = 2NO - Q 3. INTERACTION WITH WATER Does not react with water 4. INTERACTION WITH OXIDES Oxidizes lower oxides to oxides with a higher oxidation state Fe⁺²O + O2 = Fe2⁺³O3; C⁺²O + O2 = C⁺⁴O2 5. INTERACTION WITH ACIDS Anhydrous anoxic acids (binary compounds) burn in an oxygen atmosphere 2H2S + O2 = 2S + 2H2O 2H2S + 3O2 = 2SO2 + 2H2O In oxygen-containing, it increases the degree of oxidation of the non-metal. 2HN⁺³O2 + O2 = 2HN⁺⁵O3 6. INTERACTION WITH BASES Oxidizes unstable hydroxides in aqueous solutions to a higher oxidation state 4Fe(OH)2 + O2 + 2H2O = 4Fe(OH)3 7. INTERACTION WITH SALT AND BINARY COMPOUNDS Enters into combustion reactions. 4FeS2 +11O2 = 2Fe2O3 + 8SO2 CH4 + 2O2 = CO2 + 2H2O 4NH3 + 3O2 = 2N2 + 6H2O catalytic oxidation NH3 + O2 = NO + H2O CHEMICAL PROPERTIES OF THE HALOGENS 1. INTERACTION WITH METALS With alkaline under normal conditions, withF, Cl, Brignite: 2 Na + Cl2 = 2 NaCl(chloride) Alkaline earth and aluminum react under normal conditions: WITHa+Cl2=WITHaCl2 2Al+3Cl2 = 2AlCl3 Metals of secondary subgroups at elevated temperatures Cu + Cl₂ = Cu⁺²Cl₂ 2Cu + I₂ = 2Cu⁺¹I (there is no copper (II) iodide!) 2Fe + ЗС12 = 2Fe⁺³Cl3 iron (III) chloride Fluorine reacts with metals (often explosively), including gold and platinum. 2Au + 3F₂ = 2AuF 2. INTERACTION WITH NON-METALS They do not directly interact with oxygen (except for F₂), they react with sulfur, phosphorus, silicon. The chemical activity of bromine and iodine is less pronounced than that of fluorine and chlorine: H2 +F2 = 2NF ; Si + 2 F2 = SiF4.; 2 P + 3 Cl2 = 2 P⁺³ Cl3; 2 P + 5 Cl2 = 2 P⁺⁵ Cl5; S + 3 F2 = S⁺⁶ F6; S + Cl2 = S⁺²Cl2 F₂ Reacts with oxygen:F2 + O2 = O⁺² F2 Reacts with other halogens:Cl₂ + F₂ = 2 Cl⁺¹ F¯¹ Reacts even with inert gases 2F₂ + Xe= Xe⁺⁸ F₄¯¹. 3. INTERACTION WITH WATER Fluorine under normal conditions forms hydrofluoric acid + + O₂ 2F2 + 2H2O → 4HF + O2 Chlorine, when the temperature rises, forms hydrochloric acid + O₂, 2Сl₂ + 2H₂O → 4HCl + O₂ at n.o. - "chlorine water" Сl2 + Н2О ↔ НCl + НClO (hydrochloric and hypochlorous acids) Bromine under normal conditions forms "bromine water" Br2 + H2O ↔ HBr + HBrO (hydrobromic and hypobromous acids Iodine → no reaction I2 + H₂O ≠ 5. INTERACTION WITH OXIDES Only fluorine F₂ REACTS, displacing oxygen from the oxide, forming fluorides SiO2‾² + 2F2⁰ = SiF4‾¹ + O2⁰ 6. INTERACTION WITH ACIDS. react with oxygen-free acids, displacing less active non-metals. H2S‾² + I2⁰ → S⁰↓+ 2HI‾ 7. INTERACTION WITH ALKALI Fluorine forms fluoride + oxygen and water 2F2 + 4NaOH = 4NaF¯¹ + O2 + 2H2O Chlorine, when heated, forms chloride, chlorate and water. 3 Cl₂ + 6 KOH = 5 KCl¯¹ + KCl⁺⁵ O3 + 3 H2 O In the cold, chloride, hypochlorate and water, with calcium hydroxide bleach and water Cl2 + 2KOH-(cold)= KCl¯¹ + KCl⁺¹O + H2O Cl2 + Ca(OH) 2 = CaOCl2 (bleach - mixture of chloride, hypochlorite and hydroxide) + H2O Bromine when heated → bromide, bromate and and water 3Br2 + 6KOH =5KBr¯¹ + KBr ⁺⁵O3 + 3H2O Iodine when heated → iodide, iodate and water 3I2 + 6NaOH = 5NaI¯¹ + NaI ⁺⁵O3 + 3H2O 9. INTERACTION WITH SALT Displacement of less active halogens from salts 2KBr + Cl2 → 2KCl + Br2 Oxidize non-metals in salts to a higher oxidation state 2Fe⁺²Cl2 + Cl2⁰ → 2Fe⁺³Cl 3 ‾¹ Na2S⁺⁴O3 + Br2⁰ + 2H2O →Na2S⁺⁶O4 + 2HBr‾ CHEMICAL PROPERTIES OF SULFUR 1. INTERACTION WITH METALSreacts when heated even with alkali metals, with mercury under normal conditions: with sulfur - sulfides: 2K + S = K2S 2Cr + 3S = Cr2⁺³S3 Fe + S = Fe⁺²S 2. INTERACTION WITH NON-METALS When heated with hydrogen,coxygen (sulfur dioxide)chalogens (except iodine), with carbon, nitrogen and silicon and does not react S + Cl₂ = S⁺²Cl₂ ; S + O₂ =S⁺⁴O₂ H₂ + S = H₂S¯² ; 2P + 3S = P₂S₃¯² WITH+ 3S = CS₂¯² WITH WATER, OXIDES, SALT DOES NOT REACT 3. INTERACTION WITH ACIDS Oxidized by sulfuric acid when heated to sulfur dioxide and water 2H2SO4 (conc) = 2H2O + 3S⁺⁴O2 Nitric acid when heated to sulfuric acid, nitric oxide (+4) and water S + 6HNO3(conc) =H2SO4 + 6N⁺⁴O2 + 2H2O 4. INTERACTION WITH ALKALI Forms sulfite when heated, sulfide + water 3S + 6KOH = K2SO3 + 2K2S + 3H2O CHEMICAL PROPERTIES OF NITROGEN 1. INTERACTION WITH METALSreactions proceed when heated (exception: lithium with nitrogen under normal conditions): With nitrogen - nitrides 6Li + N2 = 3Li2N (lithium nitride) (n.o.) 3Mg + N2 = Mg3N2 (magnesium nitride) 2Cr + N2 = 2CrN Iron in these compounds has an oxidation state of +2 2. INTERACTION WITH NON-METALS (due to the triple bond, nitrogen is very inactive). Under normal conditions, it does not react with oxygen. Reacts with oxygen only at high temperatures (electric arc), in nature - during a thunderstorm N2+O2=2NO (email. arc, 3000 0C) With hydrogen at high pressure, elevated temperature and in the presence of a catalyst: t,p,kat 3N2+3H2 ↔ 2NH3 WITH WATER, OXIDES, ACIDS, ALKALS AND SALT DOES NOT REACT CHEMICAL PROPERTIES OF PHOSPHORUS 1. INTERACTION WITH METALS reactions proceed when heated with phosphorus - phosphides 3Ca + 2P = K3P2, Iron in these compounds has an oxidation state of +2 2. INTERACTION WITH NON-METALS Combustion in oxygen 4P + 5O₂ = 2P₂⁺⁵O₅ 4P + 3O₂ = 2P₂⁺³O₃ With halogens and sulfur when heated 2P + 3Cl₂ = 2P⁺³Cl₃ 2P + 5Cl₂ = 2P⁺⁵Cl₅; 2P + 5S = P₂⁺⁵S₅ Does not interact directly with hydrogen, carbon, silicon WITH WATER AND OXIDES DOES NOT REACT 3. INTERACTION WITH ACIDS With concentrated nitric acid nitric oxide (+4), with dilute nitric oxide (+2) and phosphoric acid 3P + 5HNO₃(conc) =3H₃PO₄ + 5N⁺⁴O₂ 3P + 5HNO₃ + 2H₂O = 3H₃PO₄ + 5N⁺²O With concentrated sulfuric acid, phosphoric acid, sulfur oxide (+4) and water are formed 3P + 5H₂SO₄(conc.) =3H₃PO₄ + 5S⁺⁴O₂+ 2H₂O 4. INTERACTION WITH ALKALI Forms phosphine and hypophosphite with alkali solutions 4P⁰ + 3NaOH + 3H2O = P¯³H 3 + 3NaH 2 P ⁺1O 2 5. INTERACTION WITH SALT 5. INTERACTION WITH SALT With strong oxidizing agents, exhibiting reducing properties 3P⁰ + 5NaN⁺⁵O₃ = 5NaN⁺³O₂ + P₂⁺⁵O₅ CHEMICAL PROPERTIES OF CARBON 1. INTERACTION WITH METALS reactions take place when heated Metals - d-elements form with carbon compounds of non-stoichiometric composition such as solid solutions: WC, ZnC, TiC - are used to obtain superhard steels with carbon carbides 2Li + 2C = Li2C2, Ca + 2C = CaC2 2. INTERACTION WITH NON-METALS Of the halogens, it directly reacts only with fluorine, with the rest when heated. С + 2F₂ = CF₄. Interaction with oxygen: 2C + O₂ (lack) \u003d 2C⁺²O (carbon monoxide), С + О₂(ex) = С⁺⁴О₂(carbon dioxide). Interaction with other non-metals at elevated temperature, does not interact with phosphorus C + Si = SiC¯⁴ ; C + N₂ = C₂⁺⁴N₂ ; C + 2H₂ = C¯⁴H₄ ; C + 2S = C⁺⁴S₂; 3. INTERACTION WITH WATER The passage of water vapor through hot coal - carbon monoxide and hydrogen are formed (synthesis gas C + H₂O = CO + H₂ 4. INTERACTION WITH OXIDES CARBON REDUCES METALS AND NON-METALS FROM OXIDES TO A SIMPLE SUBSTANCE WHEN HEATED (CARBOTHERMY), reduces the degree of oxidation in carbon dioxide 2ZnO + C = 2Zn + CO; 4WITH+ Fe₃O₄ = 3Fe + 4CO; P₂O₅ + C = 2P + 5CO; 2WITH+ SiO₂ = Si + 2CO; WITH+ C⁺⁴O₂ = 2C⁺²O 5. INTERACTION WITH ACIDS Oxidized by concentrated nitric and sulfuric acids to carbon dioxide C +2H2SO4(conc)=C⁺⁴O2+ 2S⁺⁴O2+ 2H2O; C+4HNO3 (conc) = C⁺⁴O2 + 4N⁺⁴O2 + 2H2O. WITH ALKALI AND SALT DOES NOT REACT CHEMICAL PROPERTIES OF SILICON 1. INTERACTION WITH METALS reactions proceed when heated: active metals react with silicon - silicides 4Cs + Si = Cs4Si, 1. INTERACTION WITH NON-METALS From halogens directly only with fluorine. Reacts with chlorine when heated Si + 2F2 = SiF4; Si + 2Cl2 = SiCl4; Si + O₂ = SiO₂; Si+C=SiC; 3Si + 2N₂ = Si₃N; Does not interact with hydrogen 3. INTERACTION WITH ACIDS interacts only with a mixture of hydrofluoric and nitric acids, forming hexafluorosilicic acid 3Si + 4HNO₃ + 18HF = 3H₂ + 4NO + 8H₂O Interaction with hydrogen halides (these are not acids) - displaces hydrogen, silicon halides and hydrogen are formed Reacts with hydrogen fluoride under normal conditions. Si + 4HF = SiF₄ + 2H₂ 4. INTERACTION WITH ALKALI It dissolves when heated in alkalis, forming silicate and hydrogen: Si + 2NaOH + H₂O = Na₂SiO₃ + 2H₂ Topic № 3. CHEMICAL PROPERTIES OF NON-METALS Plan 1. Basic chemical properties of non-metals. 2. Oxides of non-metallic elements. 3. Distribution of non-metallic elements in nature. 4. Application of non-metals. 1. Basic chemical properties of non-metals Non-metals (with the exception of inert gases) chemically active substances. In reactions with metals, atoms of non-metallic elements add electrons, and in reactions with non-metals, they form joint electron pairs. To find out which atom shared electron pairs are shifted to, the electronegativity series helps: F, O, N, Cl, Br, I, S, C, Se, H, P, As, B, Si electronegativity decreases
2Mg + O2 = 2MgO (magnesium oxide) 6Li + N 2 = 2Li 3 N (lithium nitride) 2Al + 3Cl 2 = 2AlCl 3 (aluminum chloride) Ca + H 2 \u003d CaH 2 (calcium hydride) Fe + S = FeS (ferum(II) sulfide) When non-metals interact with metals, binary compounds with ionic chemical bonds are formed. 2 . Interaction of non-metals with oxygen: C + O 2 \u003d CO 2 (carbon(IV) oxide) S + O 2 \u003d SO 2 (c ulfur (IV) oxide) The products of the interaction of non-metals with oxygen are binary compounds with a covalent polar bond oxides , in which oxygen has an oxidation state- 2. 3. Interaction of non-metals with hydrogen: H 2 + Cl 2 = 2HCl (hydrogen chloride or hydrogen chloride) H 2 + S = H 2 S (hydrogen sulfide or hydrogen sulfide) When non-metals interact with hydrogen, volatile (gaseous or liquid) binary compounds with a covalent polar bond are formed. 4. Interaction of nonmetals with other nonmetals: C + 2S = CS 2 (carbon(IV) sulfide) Si + 2Cl 2 \u003d SiCl 4 (silicon(IV) chloride) The products of the interaction of two non-metals are substances with a different state of aggregation, which have a covalent type of chemical bond.
Oxides of non-metallic elements are divided into: a) salt-forming (most of them) and b) non-salt-forming(CO, NO, N 2 O, H 2 O). Among the oxides there are gaseous substances (CO, CO 2, SO2 ), solids (P 2 O 5 ), liquids (H 2 O, Cl 2 O 7 ). In all oxides, without exception, the atoms of non-metallic elements, combined with oxygen, havepositive oxidation states. Most oxides of non-metallic elements acidic . They interact:
non-metals more commonin nature than metals. The composition of air includes: nitrogen, oxygen, inert gases. Deposits of native sulfur in the Carpathians are one of the largest in the world. An industrial graphite deposit in Ukraine is the Zavalyevskoye deposit, the raw material of which is used by the Mariupol graphite plant. In the Zhytomyr region, in Volyn, deposits of rocks were discovered that may contain diamonds, however industrial deposits are not yet open. Atoms of non-metallic elements form various complex substances, among which oxides and salts dominate.
Oxygen: breathing processes, Combustion, metabolism and energy, Metal production. Hydrogen: ammonia production, chloride acid, methanol, Turning liquid fats into solid ones Welding and cutting of refractory metals, Recovery of metals from ores. Sulfur: Getting sulfate acid, Making rubber from rubber match production, black powder, Manufacturing of medicines. Bor: Component of neutron absorbing materials of nuclear reactors, Protection of surfaces of steel products from corrosion, in semiconductor technology, Manufacture of converters of thermal energy into electrical energy. Nitrogen: Gaseous: For the production of ammonia, To create an inert atmosphere when welding metals, In vacuum plants, electric lamps, Liquid : As a refrigerant in freezers, Medicine. Phosphorus: White - for the production of red phosphorus, Red - for the production of matches. Silicon: IN electronics and electrical engineeringfor the manufacture of: schemes, diodes, transistors, photocells, for the manufacture of alloys. Chlorine: Production of perchloric acid, organic solvents, medicines, Monomers for the production of plastics, Bleachers, Like a disinfectant. Carbon: Diamond: Manufacture of tools for drilling and cutting, abrasive material, Jewelry, Graphite: Foundry, metallurgical, radio engineering production, battery manufacturing, In the oil and gas industry for drilling operations, Production of anti-corrosion coatings, Putties that reduce the force of friction, Adsorption. Adsorption the ability of some substances (in particular carbon) to hold particles of other substances (gas or dissolved substance) on its surface. Its use in medicine for medicinal purposes is based on the adsorption capacity of carbon - these are tablets or capsules of activated carbon. They are used orally for poisoning. Heating is sufficient to restore the adsorbent's ability to adsorb and remove the adsorbed substance. The adsorption capacity of carbon was used by M.D. Zelinsky in the coal gas mask invented by him in 1915, a means of individual protection of the respiratory organs, face and eyes of a person from the effects of harmful substances. In 1916, the industrial production of gas masks was launched, which saved the lives of hundreds of thousands of soldiers during the First World War. An improved gas mask is still used today. Homework Write the reactions of interaction: a) silicon with oxygen; b) silicon with hydrogen; c) zinc with chlorine; d) phosphorus with chlorine. Name the resulting compounds. If most of the metal elements are not colored, with the exception of only copper and gold, then almost all non-metals have their own color: fluorine - orange-yellow, chlorine - greenish-yellow, bromine - brick red, iodine - purple, sulfur - yellow, phosphorus can be white, red and black, and liquid oxygen - blue. All non-metals do not conduct heat and electric current, since they do not have free charge carriers - electrons, they are all used to form chemical bonds. Non-metal crystals are non-plastic and brittle, since any deformation leads to the destruction of chemical bonds. Most of the non-metals do not have a metallic sheen. The physical properties of non-metals are varied and are determined by different type crystal lattices. 1.4.1 AllotropyALLOTROPY - the existence of chemical elements in two or more molecular or crystalline forms. For example, allotropes are ordinary oxygen O 2 and ozone O 3; in this case, allotropy is due to the formation of molecules with different numbers of atoms. Most often, allotropy is associated with the formation of crystals of various modifications. Carbon exists in two distinct crystalline allotropic forms: diamond and graphite. Previously, it was believed that the so-called. amorphous forms of carbon, charcoal and soot, are also its allotropic modifications, but it turned out that they have the same crystalline structure as graphite. Sulfur occurs in two crystalline modifications: rhombic (a-S) and monoclinic (b-S); at least three of its non-crystalline forms are known: l-S, m-S and violet. For phosphorus, white and red modifications have been well studied; black phosphorus has also been described; at temperatures below -77 ° C, there is another kind of white phosphorus. Allotropic modifications of As, Sn, Sb, Se, and at high temperatures of iron and many other elements have been found. 1.5. Chemical properties of non-metalsNon-metal chemical elements can exhibit both oxidizing and reducing properties, depending on the chemical transformation in which they take part. The atoms of the most electronegative element - fluorine - are not able to donate electrons, it always exhibits only oxidizing properties, other elements can also exhibit reducing properties, although to a much lesser extent than metals. The strongest oxidizing agents are fluorine, oxygen and chlorine, hydrogen, boron, carbon, silicon, phosphorus, arsenic and tellurium exhibit predominantly reducing properties. Intermediate redox properties have nitrogen, sulfur, iodine. Interaction with simple substances Interaction with metals: 2Na + Cl 2 \u003d 2NaCl, 6Li + N 2 \u003d 2Li 3 N, 2Ca + O 2 \u003d 2CaO in these cases, non-metals exhibit oxidizing properties, they accept electrons, forming negatively charged particles. Interaction with other non-metals: Interacting with hydrogen, most non-metals exhibit oxidizing properties, forming volatile hydrogen compounds - covalent hydrides: 3H 2 + N 2 \u003d 2NH 3, H 2 + Br 2 = 2HBr; Interacting with oxygen, all non-metals, except for fluorine, exhibit reducing properties: S + O 2 \u003d SO 2, 4P + 5O 2 \u003d 2P 2 O 5; When interacting with fluorine, fluorine is an oxidizing agent, and oxygen is a reducing agent: 2F 2 + O 2 \u003d 2OF 2; Non-metals interact with each other, a more electronegative metal plays the role of an oxidizing agent, a less electronegative one - the role of a reducing agent: S + 3F 2 \u003d SF 6, Chemical elements - non-metalsThere are only 16 non-metal chemical elements, but two of them, oxygen and silicon, make up 76% of the mass of the earth's crust. Non-metals make up 98.5% of the mass of plants and 97.6% of the mass of a person. All the most important organic substances are composed of carbon, hydrogen, oxygen, sulfur, phosphorus and nitrogen; they are the elements of life. Hydrogen and helium are the main elements of the Universe, all space objects, including our Sun, consist of them. It is impossible to imagine our life without non-metal compounds, especially if we remember that the vital chemical compound Water is made up of hydrogen and oxygen. If we draw a diagonal from beryllium to astatine in the Periodic system, then non-metal elements will be on the diagonal upwards to the right, and metals will be on the bottom left, they also include elements of all secondary subgroups, lanthanides and actinides. Elements located near the diagonal, for example, beryllium, aluminum, titanium, germanium, antimony, have a dual character and are metalloids. Non-metal elements: s-element - hydrogen; p-elements of group 13 - boron; 14 groups - carbon and silicon; 15 groups - nitrogen, phosphorus and arsenic, 16 groups - oxygen, sulfur, selenium and tellurium and all elements of group 17 - fluorine, chlorine, bromine, iodine and astatine. Elements of group 18 - inert gases, occupy a special position, they have a completely completed outer electron layer and occupy an intermediate position between metals and non-metals. They are sometimes referred to as non-metals, but formally, according to physical characteristics.
non-metals- these are chemical elements whose atoms accept electrons to complete the external energy level, thus forming negatively charged ions. In the outer electron layer of non-metal atoms, there are from three to eight electrons. Almost all non-metals have relatively small radii and a large number of electrons in the external energy level from 4 to 7, they are characterized by high electronegativity and oxidizing properties. Therefore, compared with metal atoms, non-metals are characterized by: Smaller atomic radius four or more electrons in the outer energy level; Hence such an important property of non-metal atoms - the tendency to receive missing up to 8 electrons, i.e. oxidizing properties. A qualitative characteristic of non-metal atoms, i.e. a kind of measure of their non-metallicity, can serve as electronegativity, i.e. the property of atoms of chemical elements to polarize a chemical bond, to attract common electron pairs; The very first scientific classification of chemical elements was their division into metals and non-metals. This classification has not lost its significance at the present time. Non-metals are chemical elements whose atoms are characterized by the ability to accept electrons before the completion of the outer layer due to the presence, as a rule, of four or more electrons on the outer electron layer and the small radius of atoms compared to metal atoms. This definition leaves aside the elements of group VIII of the main subgroup - inert, or noble, gases, the atoms of which have a completed outer electron layer. The electronic configuration of the atoms of these elements is such that they cannot be attributed to either metals or non-metals. They are those objects that separate elements into metals and non-metals, occupying a boundary position between them. Inert, or noble, gases ("nobility" is expressed in inertia) are sometimes referred to as non-metals, but only formally, according to physical characteristics. These substances retain their gaseous state down to very low temperatures. Thus, helium does not go into a liquid state at t° = -268.9°C. The chemical inertness of these elements is relative. For xenon and krypton, compounds with fluorine and oxygen are known: KrF 2 , XeF 2 , XeF 4 and others. Undoubtedly, in the formation of these compounds, inert gases acted as reducing agents. From the definition of non-metals, it follows that their atoms are characterized by high values of electronegativity. It varies from 2 to 4. Non-metals are elements of the main subgroups, mainly p-elements, with the exception of hydrogen - an s-element. All non-metal elements (except hydrogen) occupy the upper right corner in the Periodic Table of Chemical Elements of D. I. Mendeleev, forming a triangle, the apex of which is fluorine F, and the base is the diagonal B - At. However, special attention should be paid to the dual position of hydrogen in the Periodic system: in the main subgroups of groups I and VII. This is no coincidence. On the one hand, the hydrogen atom, like alkali metal atoms, has one electron on the outer (and the only one for it) electron layer ( electronic configuration 1s 1), which he is able to give, showing the properties of a reducing agent. In most of its compounds, hydrogen, like the alkali metals, exhibits an oxidation state of +1. But the release of an electron by a hydrogen atom is more difficult than that of alkali metal atoms. On the other hand, the hydrogen atom, like the halogen atoms, lacks one electron to complete the outer electron layer, so the hydrogen atom can accept one electron, showing the properties of an oxidizing agent and the oxidation state characteristic of the halogen -1 in hydrides (compounds with metals, similar to metal compounds with halogens - halides). But the attachment of one electron to a hydrogen atom is more difficult than with halogens. Under normal conditions, hydrogen H 2 is a gas. Its molecule, like halogens, is diatomic. The atoms of non-metals are dominated by oxidizing properties, i.e., the ability to attach electrons. This ability characterizes the value of electronegativity, which naturally changes in periods and subgroups. Fluorine is the strongest oxidizing agent, its atoms in chemical reactions are not able to donate electrons, i.e., exhibit reducing properties. Other non-metals can exhibit reducing properties, although to a much weaker extent compared to metals; in periods and subgroups, their reducing ability changes in the reverse order compared to the oxidizing one.
The structure and physical properties of non-metalsIn simple substances, non-metal atoms are bonded covalent non-polar bond. Due to this, a more stable electronic system is formed than that of isolated atoms. In this case, single (for example, in hydrogen molecules H 2, halogens F 2, Br 2, I 2), double (for example, in sulfur molecules S 2), triple (for example, in nitrogen molecules N 2) covalent bonds are formed.
State of aggregation:
Unlike metals, non-metals are simple substances, are characterized by a wide variety of properties. Non-metals have a different state of aggregation under normal conditions:
Non-metals also have a much richer spectrum of colors: red - for phosphorus, red-brown - for bromine, yellow - for sulfur, yellow-green - for chlorine, violet - for iodine vapor. Elements - non-metals are more capable, in comparison with metals, of allotropy. The ability of atoms of one chemical element to form several simple substances is called allotropy, and these simple substances are called allotropic modifications. Simple substances - non-metals can have: 1. Molecular structure. Under normal conditions, most of these substances are gases (H 2, N 2, O 2, F 2, Cl 2, O 3) or solids (I 2, P 4, S 8), and only one single bromine (Br 2) is a liquid. All these substances have a molecular structure, therefore they are volatile. In the solid state, they are fusible due to the weak intermolecular interaction that keeps their molecules in the crystal, and are capable of sublimation. 2. Atomic structure. These substances are formed by long chains of atoms (C n , B n , Si n , Se n , Te n). Due to the high strength of covalent bonds, they, as a rule, have high hardness, and any changes associated with the destruction of the covalent bond in their crystals (melting, evaporation) are performed with a large expenditure of energy. Many of these substances have high melting and boiling points, and their volatility is very low. Many non-metal elements form several simple substances - allotropic modifications. This property of atoms is called allotropy. Allotropy can also be associated with a different composition of molecules (O 2, O 3), and with a different structure of crystals. Allotropic modifications of carbon are graphite, diamond, carbine, fullerene. To reveal the properties characteristic of all non-metals, it is necessary to pay attention to their location in the periodic system of elements and determine the configuration of the outer electronic layer.
In the period:
In the main subgroup:
Most metals, with rare exceptions (gold, copper, and some others), are characterized by a silvery-white color. But for simple substances - non-metals, the range of colors is much more diverse: P, Se - yellow; B - brown; O 2 (g) - blue; Si, As (met) - gray; P 4 - pale yellow; I - purple-black with a metallic sheen; Br 2(g) - brown liquid; C1 2(d) - yellow-green; F 2 (r) - pale green; S 8 (tv) - yellow. Non-metal crystals are non-plastic, and any deformation causes the destruction of covalent bonds. Most non-metals do not have a metallic sheen.
There are only 16 chemical elements-non-metals! Quite a bit, considering that 114 elements are known. Two non-metal elements make up 76% of the mass of the earth's crust. These are oxygen (49%) and silicon (27%). The atmosphere contains 0.03% of the mass of oxygen in the earth's crust. Non-metals make up 98.5% of the mass of plants, 97.6% of the mass of the human body. Non-metals C, H, O, N, S are biogenic elements that form the most important organic substances of a living cell: proteins, fats, carbohydrates, nucleic acids. The composition of the air we breathe includes simple and complex substances, also formed by non-metal elements (oxygen O 2, nitrogen N 2, carbon dioxide CO 2, water vapor H 2 O, etc.) Oxidizing properties of simple substances - non-metalsFor atoms of non-metals, and consequently, for the simple substances formed by them, they are characterized as oxidative, and restorative properties. 1. Oxidizing properties of non-metals appear first when interacting with metals(metals are always reducing agents):
The oxidizing properties of chlorine Cl 2 are more pronounced than those of sulfur, therefore, the Fe metal, which has stable oxidation states of +2 and +3 in compounds, is oxidized by it to a higher oxidation state. 1. Most non-metals exhibit oxidizing properties when interacting with hydrogen. As a result, volatile hydrogen compounds are formed.
2. Any non-metal acts as an oxidizing agent in reactions with those non-metals that have a lower electronegativity value:
The electronegativity of sulfur is greater than that of phosphorus, so it exhibits oxidizing properties here. The electronegativity of fluorine is greater than that of all other chemical elements, so it exhibits the properties of an oxidizing agent. Fluorine F 2 is the strongest non-metal oxidizing agent, it exhibits only oxidizing properties in reactions. 3. Non-metals also exhibit oxidizing properties in reactions with some complex substances.. First of all, we note the oxidizing properties of the non-metal oxygen in reactions with complex substances:
Not only oxygen, but also other non-metals can also be oxidizing agents in reactions with complex substances.- inorganic (1, 2) and organic (3, 4): The strong oxidizing agent chlorine Cl 2 oxidizes iron (II) chloride to iron (III) chloride;
Chlorine Cl 2 as a stronger oxidizing agent displaces free iodine I 2 from a solution of potassium iodide;
Methane halogenation is a characteristic reaction for alkanes;
A qualitative reaction to unsaturated compounds is their discoloration of bromine water.
Reducing properties of simple substances - non-metalsBy revising reactions of non-metals with each other that, depending on the value of their electronegativity, one of them exhibits the properties of an oxidizing agent, and the other - the properties of a reducing agent. 1. In relation to fluorine, all non-metals (even oxygen) exhibit reducing properties. 2. Of course, non-metals, except for fluorine, serve as reducing agents when interacting with oxygen.
As a result of the reactions, non-metal oxides: non-salt-forming and salt-forming acid. And although halogens do not combine directly with oxygen, their oxides are known: Cl 2 +1 O -2, Cl 2 +4 O 2 -2, Cl 2 +7 O 7 -2, Br 2 +1 O -2, Br +4 O 2 -2, I 2 +5 O 5 -2, etc., which are obtained indirectly.
3. Many non-metals can act as a reducing agent in reactions with complex substances - oxidizing agents: There are also reactions in which the same non-metal is both an oxidizing agent and a reducing agent. These are autoxidation-self-healing (disproportionation) reactions:
Thus, most non-metals can act in chemical reactions both as an oxidizing agent and as a reducing agent (reductive properties are not inherent only in fluorine F 2). Hydrogen compounds of non-metalsUnlike metals, non-metals form gaseous hydrogen compounds. Their composition depends on the degree of oxidation of non-metals. RH 4 → RH 3 → H 2 R → HR Common property of all non-metals is the formation of volatile hydrogen compounds, in most of which the non-metal has the lowest oxidation state. Among the given formulas of substances, there are many those whose properties, application and preparation you studied earlier: CH 4, NH 3, H 2 O, H 2 S, HCl.
It is known that these compounds can be obtained most simply directly. interaction of a non-metal with hydrogen, that is, by synthesizing:
All hydrogen compounds of non-metals are formed by covalent polar bonds, have a molecular structure and under normal conditions are gases, except for water (liquid). Hydrogen compounds of non-metals are characterized by a different relationship to water. Methane and silane are practically insoluble in it. Ammonia, when dissolved in water, forms a weak base NH 3 H 2 O. When hydrogen sulfide, hydrogen selenide, hydrogen telluride, and hydrogen halides are dissolved in water, acids are formed with the same formula as the hydrogen compounds themselves: H 2 S, H 2 Se, H 2 Te, HF, HCl, HBr, HI. If we compare the acid-base properties of hydrogen compounds formed by non-metals of one period, for example, the second (NH 3, H 2 O, HF) or the third (PH 3, H 2 S, HCl), then we can conclude that their acidic properties naturally increase and, accordingly, the weakening of the main ones. This is obviously due to the fact that the polarity increases E-N communications(where E is a non-metal). The acid-base properties of hydrogen compounds of non-metals of the same subgroup also differ. For example, in the series of hydrogen halides HF, HCl, HBr, HI, the strength of the E-H bond decreases, since the bond length increases. In solutions of HCl, HBr, HI dissociate almost completely - these are strong acids, and their strength increases from HF to HI. At the same time, HF refers to weak acids, which is due to another factor - intermolecular interaction, the formation of hydrogen bonds …H-F…H-F… . Hydrogen atoms are bonded to fluorine atoms F not only of their own molecule, but also of the neighboring one. Summarizing the comparative characteristics of the acid-base properties of hydrogen compounds of non-metals, we conclude that the acidic and weakening of the basic properties of these substances are enhanced by periods and main subgroups with an increase in the atomic numbers of the elements that form them. According to the period in the PS of chemical elements, with an increase in the serial number of the element - non-metal, the acidic nature of the hydrogen compound increases. SiH 4 → PH 3 → H 2 S → HCl In addition to the considered properties, hydrogen compounds of non-metals in redox reactions always exhibit the properties of reducing agents, because in them the non-metal has the lowest oxidation state. Hydrogen
Hydrogen is the main element of the Universe. Many space objects (gas clouds, stars, including the Sun) are more than half made up of hydrogen. On Earth, it, including the atmosphere, hydrosphere and lithosphere, is only 0.88%. But this is by mass, and the atomic mass of hydrogen is very small. Therefore, its small content is only apparent, and out of every 100 atoms on Earth, 17 are hydrogen atoms. In the free state, hydrogen exists in the form of H 2 molecules, the atoms are bound into a molecule covalent non-polar bond. Hydrogen (H 2) is the lightest of all gaseous substances. It has the highest thermal conductivity and the lowest boiling point (after helium). Slightly soluble in water. At a temperature of -252.8 °C and atmospheric pressure, hydrogen passes into a liquid state. 1. The hydrogen molecule is very strong, which makes it inactive: H 2 \u003d 2H - 432 kJ 2. At ordinary temperatures, hydrogen reacts with active metals: Ca + H 2 \u003d CaH 2, forming calcium hydride, and with F 2, forming hydrogen fluoride: F 2 + H 2 \u003d 2HF 3. At high temperatures get ammonia: N 2 + 3H 2 \u003d 2NH 3and titanium hydride (metal in powder): Ti + H 2 \u003d TiH 24. When ignited, hydrogen reacts with oxygen: 2H 2 + O 2 \u003d 2H 2 O + 484 kJ5. Hydrogen has a restorative ability: CuO + H 2 \u003d Cu + H 2 O
Elements of the main subgroup of group VII of the periodic system, united under a common name halogens, fluorine (F), chlorine (Cl), bromine (Bg), iodine (I), astatine (At) (rarely found in nature) are typical non-metals. This is understandable, because their atoms contain outer energy level has seven electrons, and they only need one electron to complete it. The atoms of these elements, when interacting with metals, accept an electron from metal atoms. In this case, an ionic bond occurs and salts are formed. Hence the common name "halogens", i.e. "giving birth to salts." very strong oxidizers. Fluorine in chemical reactions exhibits only oxidizing properties, and it is characterized by an oxidation state of -1. The remaining halogens can also exhibit reducing properties when interacting with more electronegative elements - fluorine, oxygen, nitrogen, while their oxidation states can take on the values +1, +3, +5, +7. The reducing properties of halogens increase from chlorine to iodine, which is associated with an increase in the radii of their atoms: there are about half as many chlorine atoms as those of iodine.
Halogens are simple substancesAll halogens exist in the free state as diatomic molecules with a covalent non-polar chemical bond between the atoms. In the solid state, F 2, Cl 2, Br 2, I 2 have molecular crystal lattices, which is confirmed by their physical properties.
With an increase in the molecular weight of halogens, the melting and boiling points increase, and the density increases: bromine is a liquid, iodine is a solid, fluorine and chlorine are gases. This is due to the fact that with an increase in the size of atoms and molecules of halogens, the forces of intermolecular interaction between them increase. From F 2 to I 2, the color intensity of the halogens increases. |
