IN school course four main classes of complex substances are studied: oxides, bases, acids, salts.

Oxides

- this is complex substances composed of two elements, one of which is oxygen.

Oxides are divided into:

non-salt-forming - do not interact with acids or alkalis and do not form salts. These are nitric oxide (I) N 2 O, nitrogen oxide (II) NO, carbon monoxide (II) CO and some others.

salt-forming - when interacting with acids or bases, they form salt and water.

In turn, they are divided into:

the main - the grounds correspond to them. These include metal oxides with low oxidation states (+1, +2). They are all solids)

acidic - they correspond to acids. These include oxides of non-metals and metal oxides with high oxidation states. For example, chromium oxide (VI) CrO 3, manganese (VII) oxide Mn 2 O 7.

amphoteric - depending on the conditions, show basic or acidic properties, i.e. have dual properties. These are zinc oxide ZnO, aluminum oxide Al 2 O 3, iron (III) oxide Fe 2 O 3, chromium (III) oxide Cr 2 O 3.

Typical reactions of basic oxides

1. Basic oxide + water = alkali (! The reaction proceeds if a soluble base is formed!)

K 2 O + H 2 O = 2KOH

CaO + H 2 O = Ca (OH) 2

2. Basic oxide + acidic oxide = salt

CaO + N 2 O 5 = Ca (NO 3) 2

MgO + SiO 2 = MgSiO 3

3. Basic oxide + acid = salt + water

FeO + H 2 SO 4 = FeSO 4 + H 2 O

CuO + 2HNO 3 = Cu (NO 3) 2 + H 2 O

Typical reactions of acidic oxides

1. Acidic oxide + water = acid (except for silicon oxide SiO 2)

SO 2 + H 2 O = H 2 SO 3

CrO 3 + H 2 O = H 2 CrO 4

2. Acidic oxide + basic oxide = salt

SO 3 + K 2 O = K 2 SO 4

CO 2 + CaO = CaCO 3

3. Acid oxide + base = salt + water

SO 2 + 2NaOH = Na 2 SO 3 + H 2 O

N 2 O 5 + Ca (OH) 2 = Ca (NO 3) 2 + H 2 O

Typical reactions of amphoteric oxides

1. Amphoteric oxide + acid = salt + water

ZnO + 2HCl = ZnCl 2 + H 2 O

Al 2 O 3 + 6HCl = 2AlCl 3 + 3H 2 O

2. Amphoteric oxide + alkali = salt + water

ZnO + 2NaOH + H 2 O = Na 2

Al 2 O 3 + 2NaOH + 3H 2 O = 2Na

Cr 2 O 3 + 2NaOH + 7H 2 O = 2Na

When fusion

ZnO + 2KOH = K 2 ZnO 2 + H 2 O

Al 2 O 3 + 2NaOH = 2NaAlO 2 + H 2 O

Cr 2 O 3 + 2NaOH = 2NaCrO 2 + H 2 O

Foundations

are complex substances, which include metal atoms connected to one or more hydroxyl groups.

The grounds are divided into:

water soluble (alkali) - formed by elements of group I of the main subgroup LiOH, NaOH, KOH, RbOH, CsOH and elements of group II of the main subgroup (except magnesium and beryllium) Ca (OH) 2, Sr (OH) 2, Ba (OH) 2.

insoluble in water - other.

Reactions common to all bases

1. Base + acid = salt + water

2KOH + H 2 SO 4 = K 2 SO 4 + 2H 2 O

Cu (OH) 2 + 2HCl = CuCl 2 + H 2 O

Typical alkali reactions

1. Aqueous solutions change the color of indicators (litmus - blue, methyl orange - yellow, phenolphthalein - raspberry)

KOH = K + + OH - (OH ions - cause an alkaline reaction of the medium)

Ca (OH) 2 = Ca 2 + + 2OH -

2. Alkali + acidic oxide = salt + water

Ca (OH) 2 + N 2 O 5 = Ca (NO 3) 2 + H 2 O

2KOH + CO 2 = K 2 CO 3 + H 2 O

3. Alkali + salt = salt + base (if the reaction product is an insoluble compound or poorly dissociating substance NH 4 OH)

2NaOH + CuSO 4 = Na 2 SO 4 + Cu (OH) 2 (insol.)

Ca (OH) 2 + Na 2 SiO 3 = CaSiO 3 (insol.) + 2NaOH

NaOH + NH 4 Cl = NaCl + NH 4 OH

4. Reacts with fats to form soap

Typical reactions of insoluble bases

1. Decompose when heated

Fe (OH) 2 = FeO + H 2 O

2Fe (OH) 3 = Fe 2 O 3 + 3H 2 O

Among the insoluble bases are amphoteric. For example, Be (OH) 2, Zn (OH) 2, Ge (OH) 2, Pb (OH) 2, Al (OH) 3, Cr (OH) 3, Sn (OH) 4, etc.

They interact with alkalis in aqueous solution

Zn (OH) 2 + 2NaOH = Na 2

Fe (OH) 3 + NaOH = Na

or when fusion

Zn (OH) 2 + 2NaOH = Na 2 ZnO 2 + 2H 2 O

Fe (OH) 3 + NaOH = NaFeO 2 + 2H 2 O

Acids

- These are complex substances consisting of hydrogen atoms that can be replaced by metal atoms, and acid residues.

Reactions common to all acids

1. Acid + base = salt + water

2HNO 3 + Cu (OH) 2 = Cu (NO 3) 2 + 2H 2 O

2HCl + Ca (OH) 2 = CaCl 2 + 2H 2 O

2. Acid + basic oxide = salt + water

CuO + H 2 SO 4 = CuSO 4 + 2H 2 O

3CaO + 2H 3 PO 4 = Ca 3 (PO 4) 2 + 3H 2 O

Salt

- These are complex substances, which include metal atoms and acid residue.

Salts are divided into:

average - contain only metal atoms as cations and only acid residue as anions. They can be considered as products of complete replacement of hydrogen atoms in the acid composition by metal atoms or products of complete replacement of hydroxo groups in the basic hydroxide molecule with acid residues.

H 2 SO 4 + 2NaOH = Na 2 SO 4 + 2H 2 O

3H 2 SO 4 + 2Fe (OH) 3 = Fe 2 (SO 4) 3 + 6H 2 O

sour - contain not only metal atoms as cations, but also hydrogen. They can be considered as products of incomplete replacement of hydrogen atoms in the composition of the acid. Formed only by polybasic acids. Obtained when there is not enough base to form a medium salt.

H 2 SO 4 + NaOH = NaHSO 4 + H 2 O

the main - as anions, they contain not only an acid residue, but also a hydroxyl group. They can be considered as products of incomplete substitution of hydroxo groups in the composition of a multi-acid base by an acid residue. Formed only by multi-acid bases. Obtained when there is not enough acid to form a medium salt.

H 2 SO 4 + Fe (OH) 3 = FeOHSO 4 + 2H 2 O

Typical reactions of medium salts

1. Salt + acid = other salt + other acid (The reaction proceeds if an insoluble compound is formed, gas is released - carbon dioxide CO 2, sulphurous SO 2, hydrogen sulfide H 2 S - or a low-dissociating substance is formed, for example, acetic acid CH 3 COOH!)

BaCl 2 + H 2 SO 4 = BaSO 4 ↓ + 2HCl

Na 2 CO 3 + H 2 SO 4 = Na 2 SO 4 + CO 2 + H 2 O

(CH 3 COO) 2 Ca + 2HNO 3 = Ca (NO 3) 2 + 2CH 3 COOH

As a result of this reaction, you can get volatile acids: nitrogen and salt, if you take solid salt and strong concentrated acid(sulfuric is better)

2NaCl + H 2 SO 4 = Na 2 SO 4 + 2HCl

2KNO 3 + H 2 SO 4 = K 2 SO 4 + 2HNO 3

2. Salt + alkali = other salt + other base (The reaction proceeds if an insoluble compound is formed or a poorly dissociating substance is formed, for example, ammonium hydroxide NH 4 OH!)

Cu (NO 3) 2 + 2NaOH = 2NaNO 3 + Cu (OH) 2 ↓

NH 4 Cl + NaOH = NaCl + NH 4 OH

3. Salt (1) + salt (2) = salt (3) + salt (4) (The reaction proceeds if an insoluble compound is formed!)

NaCl + AgNO 3 = NaNO 3 + AgCl ↓

CaCl 2 + Na 2 CO 3 = CaCO 3 ↓ + 2NaCl

4. Salt + metal = other salt + other metal (The metal displaces from salt solutions all other metals standing in the series of metal voltages to the right of it. The reaction proceeds if both salts are soluble, and the metal itself does not interact with water!)

CuCl 2 + Fe = FeCl 2 + Cu

2AgNO 3 + Cu = Cu (NO 3) 2 + 2Ag

5. Decomposition reactions:

a) carbonates. Insoluble bivalent metal carbonates decompose mainly on heating into oxide and carbon dioxide. Of alkali metals the reaction is typical for lithium carbonate in an inert atmosphere.

b) bicarbonates decompose into carbonates, carbon dioxide and water.

c) nitrates: according to the scheme - up to magnesium inclusively, according to a number of metal voltages, they decompose into nitrite and oxygen; from magnesium to copper, inclusive to metal oxide (often the metal changes its oxidation state to a higher one), nitrogen oxide (IV) and oxygen; after copper to metal, nitric oxide (IV) and oxygen.

Typical reactions of acidic salts

1. Sour salt + alkali = medium salt + water

NaHSO 4 + NaOH = Na 2 SO 4 + H 2 O

Typical reactions of basic salts

1. Basic salt + alkali = medium salt + water

(CuOH) 2 CO 3 + H 2 CO 3 = CuCO 3 ↓ + 2H 2 O

Inorganic substances They are divided into classes either by composition (binary and multi-element; oxygen-containing, nitrogen-containing, etc.), or by functional characteristics.

To the most important classes inorganic compounds, allocated on functional grounds, include salts, acids, bases and oxides.

Salt- these are compounds that dissociate in solution into metal cations and acid residues. Examples of salts include, for example, barium sulfate BaSO 4 and zinc chloride ZnCl 2.

Acids- substances that dissociate in solutions with the formation of hydrogen ions. Examples of inorganic acids include hydrochloric (HCl), sulfuric (H 2 SO 4), nitric (HNO 3), phosphoric (H 3 PO 4) acids. The most characteristic chemical property of acids is their ability to react with bases to form salts. According to the degree of dissociation in dilute solutions, acids are subdivided into strong acids, acids of medium strength and weak acids. According to the redox capacity, there are oxidizing acids (HNO 3) and reducing acids (HI, H 2 S). Acids react with bases, amphoteric oxides and hydroxides to form salts.

Foundations- substances that dissociate in solutions with the formation of only hydroxide anions (OH 1–). Water-soluble bases are called alkalis (KOH, NaOH). A characteristic property of bases is interaction with acids with the formation of salt and water.

Oxides Is a compound of two elements, one of which is oxygen. Distinguish between basic oxides, acidic and amphoteric. Basic oxides are formed only by metals (CaO, K 2 O), they correspond to bases (Ca (OH) 2, KOH). Acidic oxides are formed by non-metals (SO 3, P 2 O 5) and metals exhibiting a high oxidation state (Mn 2 O 7), they correspond to acids (H 2 SO 4, H 3 PO 4, HMnO 4). Amphoteric oxides, depending on the conditions, exhibit acidic and basic properties, interact with acids and bases. These include Al 2 O 3, ZnO, Cr 2 O 3 and a number of others. There are oxides that exhibit neither basic nor acidic properties. Such oxides are called indifferent (N 2 O, CO, etc.)

Classification of organic compounds

Carbon in organic compounds usually forms stable structures based on carbon-carbon bonds. In its ability to form such structures, carbon is unmatched among other elements. Most organic molecules consists of two parts: a fragment that remains unchanged during the reaction, and a group that undergoes transformations. In this regard, the belonging of organic substances to one or another class and a number of compounds is determined.

An invariable fragment of an organic compound molecule is usually considered as the backbone of a molecule. It can be of hydrocarbon or heterocyclic nature. In this regard, it is possible to conventionally distinguish four large series of compounds: aromatic, heterocyclic, alicyclic and acyclic.

IN organic chemistry additional series are also distinguished: hydrocarbons, nitrogen-containing compounds, oxygen-containing compounds, sulfur-containing compounds, halogen-containing compounds, organometallic compounds, organosilicon compounds.

As a result of the combination of these fundamental series, composite series are formed, for example: "Acyclic hydrocarbons", "Aromatic nitrogen-containing compounds".

The presence of certain functional groups or atoms of elements determines the belonging of the compound to the corresponding class. Among the main classes of organic compounds are alkanes, benzenes, nitro- and nitroso compounds, alcohols, phenols, furans, ethers and a large number of others.

Our task does not include a detailed description of organic compounds, their nomenclature, structure and chemical properties. Students are encouraged to recall the school course in general and organic chemistry or to refer to numerous literary sources.

Types of chemical bonds

Chemical bond Is an interaction that holds two or more atoms, molecules, or any combination of them. By its nature, a chemical bond is an electrical force of attraction between negatively charged electrons and positively charged atomic nuclei. The magnitude of this attractive force depends mainly on the electronic configuration of the outer shell of the atoms.

The ability of an atom to form chemical bonds is characterized by its valence. The electrons involved in the formation of a chemical bond are called valence electrons.

There are several types of chemical bonds: covalent, ionic, hydrogen, metallic.

In education covalent bond there is a partial overlap of the electron clouds of interacting atoms, and electron pairs are formed. The covalent bond turns out to be the stronger than in to a greater extent overlapping interacting electronic clouds.

Distinguish between polar and non-polar covalent bonds.

If a diatomic molecule consists of identical atoms (H 2, N 2), then the electron cloud is distributed in space symmetrically relative to both atoms. This covalent bond is called non-polar (homeopolar). If a diatomic molecule consists of different atoms, then the electron cloud is displaced towards an atom with a greater relative electronegativity. This covalent bond is called polar (heteropolar). Examples of compounds with such a bond are HCl, HBr, HJ.

In the examples considered, each of the atoms has one unpaired electron; when two such atoms interact, a common electron pair is created - a covalent bond arises. There are three unpaired electrons in the unexcited nitrogen atom, due to these electrons, nitrogen can participate in the formation of three covalent bonds (NH 3). A carbon atom can form 4 covalent bonds.

Overlapping of electron clouds is possible only when they have a certain mutual orientation, while the overlap region is located in a certain direction with respect to the interacting atoms. In other words, the covalent bond is directional. The energy of covalent bonds is in the range of 150–400 kJ / mol.

The chemical bond between ions, carried out by electrostatic attraction, is called ionic bond ... It can be considered as the limit of the polar covalent bond. The ionic bond, in contrast to the covalent bond, does not possess directionality and saturation.

An important type of chemical bond is the bond of electrons in a metal. Metals are composed of positive ions, which are held at the sites of the crystal lattice, and free electrons. When a crystal lattice is formed, the valence orbitals of neighboring atoms overlap and electrons move freely from one orbital to another. These electrons no longer belong to a particular metal atom, they are in giant orbitals that extend across the entire crystal lattice. The chemical bond, carried out as a result of the bonding of positive ions of the metal lattice by free electrons, is called metal.

Weak bonds can occur between molecules (atoms) of substances. One of the most important - hydrogen bond which could be intermolecular and intramolecular... A hydrogen bond occurs between the hydrogen atom of the molecule (it is partially positively charged) and the strongly electronegative element of the molecule (fluorine, oxygen, etc.). The energy of a hydrogen bond is much less than the energy of a covalent bond and does not exceed 10 kJ / mol. However, this energy turns out to be enough to create associations of molecules that make it difficult for the molecules to separate from each other. Hydrogen bonds play an important role in biological molecules and largely determine the properties of water.

Van der Waals forces also refer to weak ties. They are due to the fact that any two neutral molecules (atoms) at very close distances are weakly attracted due to the electromagnetic interactions of the electrons of one molecule with the nuclei of another, and vice versa.

The philosophical truth: everything in our world is relative, is also true for the classification of substances and their properties. The great variety of substances in the Universe and on our planet consists of only 90 chemical elements. In nature, there are substances built by elements with serial numbers from 1 to 91, inclusive. Element 43 - technetium, is not found in nature on Earth at present, because this element has no stable isotopes. It was obtained artificially as a result of a nuclear reaction. Hence the name of the element - from the Greek. téhnos - artificial.
All earthly natural chemical substances built from 90 elements can be divided into two large types - inorganic and organic.
Organic substances are called carbon compounds with the exception of the simplest: carbon oxides, metal carbides, carbonic acid and its salts. All other substances are inorganic.
There are more than 27 million organic substances - much more than inorganic ones, the number of which, according to the most optimistic estimates, does not exceed 400 thousand. We will talk about the reasons for the diversity of organic compounds a little later, but for now we note that there is no sharp boundary between these two groups of substances. For example, the ammonium isocyanate salt NH4NCO is considered an inorganic compound, and urea (NH2) 2CO, which has exactly the same elemental composition N2H4CO, is an organic substance.
Substances that have the same molecular formula, but different chemical structures, are called isomers.
Inorganic substances are usually divided into two subtypes - simple and complex (Scheme 1). As you already know, simple substances are called substances consisting of atoms of one chemical element, and complex ones - from two or more chemical elements.
Scheme 1

Classification of inorganic substances

It would seem that the number simple substances must match the number of chemical elements. However, it is not. The fact is that atoms of one and the same chemical element can form not one, but several different simple substances. This phenomenon, as you know, is called allotropy. The causes of allotropy can be different number atoms in a molecule (for example, allotropic modifications of the element oxygen - oxygen O2 and ozone O3), as well as various structures of the crystal lattice of a solid (for example, the allotropic modifications of carbon already familiar to you - diamond and graphite).
In the subtype of simple substances, metals, non-metals and noble gases are distinguished, and the latter are often referred to as non-metals. This classification is based on the properties of simple substances, due to the structure of the atoms of chemical elements from which these substances are formed, and the type of crystal lattice. Everyone knows that metals conduct electricity, are thermally conductive, plastic, have a metallic luster. Non-metals, as a rule, do not possess such properties. Our clause "as a rule" is not accidental, and it once again emphasizes the relativity of the classification of simple substances. Some metals in their properties resemble non-metals (for example, the allotropic modification of tin - gray tin is a gray powder, does not conduct electric current, lacks luster and plasticity, while white tin, another allotropic modification, is a typical metal). In contrast, the non-metallic graphite, an allotropic modification of carbon, is highly electrically conductive and has a characteristic metallic luster.
The most general classification of complex inorganic substances is well known to you from the course of chemistry in basic school. Four classes of compounds are distinguished here: oxides, bases, acids and salts.
The division of inorganic substances into classes is carried out on the basis of their composition, which, in turn, affects the properties of the compounds. Let us recall the definitions of representatives of each class.
Oxides - complex substances, consisting of two elements, one of which is oxygen in the oxidation state –2 (for example, H2O, CO2, CuO).
Foundations Are complex substances consisting of a metal atom and one or more hydroxy groups (for example, NaOH, Ca (OH) 2).
Acids Are complex substances consisting of hydrogen atoms and an acidic residue (for example, HCl, HNO3, H2SO4, H3PO4).
Salt Are complex substances consisting of metal atoms and acidic residues (for example, NaNO3, K2SO4, AlCl3).
Such classification and definitions are also very relative. First, the role of metal in bases and salts can be played by complex particles like the familiar ammonium cation NH4 +, which consists only of nonmetal elements. Secondly, there is a fairly numerous group of substances that, according to their composition, are bases, and according to their properties they are amphoteric hydroxides, i.e. combine the properties of bases and acids. For example, aluminum hydroxide Al (OH) 3, when interacting with an acid, behaves like a base:
Al (OH) 3 + 3HCl = AlCl3 + 3H2O,
and when fused with alkalis, it exhibits acid properties:
H3AlO3 + NaOH = NaAlO2 + H2O.
Thirdly, the above classification of complex inorganic substances does not include a large number of compounds that cannot be attributed to any of the listed classes. These are, for example, compounds formed by two or more non-metallic elements (phosphorus (V) chloride PCl5, carbon sulfide CS2, phosgene COCl2).
? 1. What substances are called inorganic and what are called organic? Give examples. Prove the relativity of such a classification of substances.
2. What substances are called simple and what are called complex? Why does the number of simple substances exceed the number of chemical elements?
3. What is the classification of simple substances? Give examples of each type of substance. Are noble gases atomic or molecular? Give arguments in favor of both points of view.
4. What inorganic substances are called oxides, bases, acids, salts? Give examples of substances of each class, illustrate their properties with two or three equations chemical reactions.
5. Using the equations of chemical reactions, prove that amphoteric hydroxides exhibit the properties of both acids and bases.
6. Calcium carbonate (chalk, marble, limestone) inspired sculptors, artists, poets. For example:

The classification of inorganic substances and their nomenclature are based on the simplest and most constant characteristic over time -

chemical composition , which shows the atoms of the elements that make up a given substance, in their numerical ratio. If a substance is made of atoms of one chemical element, i.e. is a form of existence of this element in a free form, then it is called a simple substance; if a substance is made of atoms of two or more elements, then it is called complex substance... All simple substances (except monoatomic) and all complex substances are usually called chemical compounds, since in them the atoms of one or different elements are interconnected by chemical bonds.

The nomenclature of inorganic substances consists of formulas and names. Chemical formula - depicting the composition of a substance using symbols of chemical elements, numerical indices and some other signs. Chemical name - depicting the composition of a substance using a word or a group of words. The construction of chemical formulas and names is determined by the system nomenclature rules .

Symbols and names of chemical elements are given in Periodic table elements of D.I. Mendeleev. Elements are conventionally divided into metals

and non-metals ... All elements VIII belong to non-metals. A-groups (noble gases) and Vii A-groups (halogens), elements VI A-groups (except for polonium), elements nitrogen, phosphorus, arsenic ( V A group); carbon, silicon ( IVA group); boron (III A-group), as well as hydrogen. The rest of the elements are classified as metals.

When compiling the names of substances, Russian names of elements are usually used, for example, dioxygen, xenon difluoride, potassium selenate. Traditionally, for some elements, the roots of their Latin names are introduced into derivative terms:

Ag - Argent	N - nitr
As - ars, arsen	Ni - nikkol
Au - aur	O - ox, oxygen
C - carb, carbon	Pb - plumb
Cu - cupr	S - sulf
Fe - ferr	Sb - stib
H - hydr, hydrogen	Si - forces, silik, silits
Hg - merkur	Sn - stann
Mn - mangan

for example

: carbonate, manganate, oxide, sulfide, silicate.

Names simple substances consist of one word - the name of a chemical element with a numeric prefix, for example:

The following are used numeric prefixes

:

1 - mono	7 - hepta
2 - di
3 - three	9 - nona
4 - tetra
5 - penta	11 - undeca
6 - hexa	12 - dodeca

An indefinite number is indicated by a numeric prefix

n - poly.

For some simple substances, they also use special names such as O

3 - ozone, P 4 - white phosphorus.

Chemical formulas complex substances make up from the designation electropositive(conditional and real cations) and electronegative(conditional and real anions) components, for example,

CuSO 4 (here Cu 2+ - real cation, SO 4 2- - real anion) and PCl 3 (here P + III - conditional cation, Cl - I - conditional anion).

Names complex substances make up according to chemical formulas from right to left. They are made up of two words - the names of electronegative components (in the nominative case) and electropositive components (in the genitive case), for example:

CuSO 4 - copper (II) sulfate
PCl 3 - phosphorus trichloride
LaCl 3 - lanthanum (III) chloride
CO - carbon monoxide

The number of electropositive and electronegative components in the names is indicated by the numerical prefixes given above (universal method), or by the oxidation states (if they can be determined by the formula) using Roman numerals in parentheses (the plus sign is omitted). In some cases, the charge of ions is given (for complex cations and anions) using Arabic numerals with the appropriate sign.

For common multi-element cations and anions, the following special names are used:

H 2 F + - fluoronium	C 2 2- - acetylenide
H 3 O + - oxonium	CN - - cyanide
H 3 S + - sulfonium	CNO - - fulminate
NH 4 + - ammonium	HF 2 - - hydrodifluoride
N 2 H 5 + - hydrazinium (1+)	HO 2 - - hydroperoxide
N 2 H 6 + - hydrazinium (2+)	HS - - hydrosulfide
NH 3 OH + - hydroxylamine	N 3 - - azide
NO + - nitrosyl	NCS - - thiocyanate
NO 2 + - nitroyl	O 2 2 - - peroxide
O 2 + - dioxygenyl	O 2 - - superoxide
PH 4 + - phosphonium	O 3 - - ozonide
VO 2 + - vanadyl	OCN - - cyanate
UO 2 + - uranyl	OH - - hydroxide

For a small number of well-known substances, also use special titles:

AsH 3 - arsine	HN 3 - hydrogen azide
B 2 H 6 - borane	H 2 S - hydrogen sulfide
B 4 H 10 - tetraborane (10)	NH 3 - ammonia
HCN - hydrogen cyanide	N 2 H 4 - hydrazine
HCl - hydrogen chloride	NH 2 OH - hydroxylamine
HF - hydrogen fluoride	PH 3 - phosphine
HI - hydrogen iodide	SiH 4 - silane

Hydroxides are a type of complex substance that contains atoms of some element E (except for fluorine and oxygen) and OH hydroxo groups; general formula of hydroxides E (OH)

n where n= 1 ÷ 6. Form of hydroxides E (OH)ncalled ortho -form; at n> 2 the hydroxide can also be found in meta -a form that includes, in addition to atoms E and OH groups, oxygen atoms O, for example, E (OH) 3 and EO (OH), E (OH) 4 and E (OH) 6 and EO 2 (OH) 2.

Hydroxides are divided into two groups with opposite chemical properties: acidic and basic hydroxides.

Acidic hydroxides contain hydrogen atoms that can be replaced by metal atoms if the rule of stoichiometric valence is observed. Most acidic hydroxides are found in meta-form, and hydrogen atoms in the formulas of acidic hydroxides are put in the first place, for example

H 2 SO 4, HNO 3 and H 2 CO 3, not SO 2 (OH) 2, NO 2 (OH) and CO (OH) 2 ... The general formula of acidic hydroxides is H x EO at, where the electronegative component EO y x- called acid residue. If not all hydrogen atoms are replaced by a metal, then they remain in the acid residue.

The names of common acidic hydroxides consist of two words: their own name with the ending “ah” and the group word “acid”. Here are the formulas and proper names of common acidic hydroxides and their acidic residues (a dash means that the hydroxide is not known in free form or in an acidic aqueous solution):

acidic hydroxide	acid residue
HAsO 2 - metarsenic	AsO 2 - - meta-arsenite
H 3 AsO 3 - orthoarsenic	AsO 3 3- - orthoarsenite
H 3 AsO 4 - arsenic	AsO 4 3- - arsenate
	4 О 7 2- - tetraborate
	iО 3 - - bismuthate
HBrO - hypobromous	BrO - - hypobromite
HBrO 3 - bromic	BrO 3 - - bromate
H 2 CO 3 - coal	CO 3 2- - carbonate
HClO - hypochlorous	ClO - - hypochlorite
HClO 2 - chloride	ClO 2 - - chlorite
HClO 3 - chloric	ClO 3 - - chlorate
HClO 4 - chloric	ClO 4 - - perchlorate
H 2 CrO 4 - chrome	CrO 4 2- - chromate
	CrO 4 - - hydrochromate
H 2 Cr 2 O 7 - dichromic	Cr 2 O 7 2- - dichromate
	FeO 4 2- - ferrate
HIO 3 - iodic	IO 3 - - iodate
HIO 4 - metayode	IO 4 - - metaperiodate
H 5 IO 6 - orthoiodic	IO 6 5- - orthoperiod
HMnO 4 - manganese	MnO 4 - - permanganate
	MnO 4 2- - manganate
	Mo O 4 2- - molybdate
HNO 2 - nitrogenous	NO 2 - - nitrite
HNO 3 - nitrogen	NO 3 - - nitrate
HPO 3 - metaphosphoric	PO 3 - - metaphosphate
H 3 PO 4 - orthophosphoric	PO 4 3- - orthophosphate
	PO 4 2- - hydrogen phosphate
	2 PO 4 - - dihydrogen phosphate
H 4 P 2 O 7 - diphosphoric	P 2 O 7 4- - diphosphate
	ReO 4 - - perrnat
	SO 3 2- - sulfite
	HSO 3 - - hydrosulfite
H 2 SO 4 - sulfuric	SO 4 2- - sulfate
	SO 4 - - hydrogen sulfate
H 2 S 2 O 7 - disulfide	S 2 O 7 2- - disulfate
H 2 S 2 O 6 (O 2) - peroxodisulfuric	S 2 O 6 (O 2) 2- - peroxodisulfate
H 2 SO 3 S - thiosulfur	SO 3 S 2- - thiosulfate
H 2 SeO 3 - selenium	SeO 3 2- - selenite
H 2 SeO 4 - selenium	SeO 4 2- - selenate
H 2 SiO 3 - metasilicon	SiO 3 2- - metasilicate
H 4 SiO 4 - orthosilicon	SiO 4 4- - orthosilicate
H 2 TeO 3 - tellurium	TeO 3 2- - tellurite
H 2 TeO 4 - metatelluric	TeO 4 2- - metatellurate
H 6 TeO 6 - Orthotelluric	TeO 6 6- - orthotellurate
	VO 3 - - metavanadat
	VO 4 3- - orthovanadat
	WO 4 3- - tungstate

Less common acidic hydroxides are named after the nomenclature rules for complex compounds, for example:

The names of acidic residues are used when constructing the names of salts.

Basic hydroxides contain hydroxide ions, which can be replaced by acid residues if the rule of stoichiometric valence is observed. All major hydroxides are found in ortho-form; their general formula is M (OH)

n where n= 1.2 (less often 3.4) and M n +- metal cation. Examples of formulas and names of basic hydroxides:

The most important chemical property of basic and acidic hydroxides is their interaction with each other with the formation of salts ( salt formation reaction), eg:

Ca (OH) 2 + H 2 SO 4 = CaSO 4 + 2H 2 O

Ca (OH) 2 + 2H 2 SO 4 = Ca (HSO 4) 2 + 2H 2 O

2Ca (OH) 2 + H 2 SO 4 = Ca 2 SO 4 (OH) 2 + 2H 2 O

Salt - the type of complex substances, which include M cations

n+ and acidic residues *.

Salts with general formula M x(EO at

)n are called average salts, and salts with unsubstituted hydrogen atoms - sour salts. Sometimes salts also contain hydroxide - and / or oxide - ions; such salts are called the main salts. Here are examples and names of salts:

	- calcium orthophosphate
	- calcium dihydrogen phosphate
	- calcium hydrogen phosphate
	Copper (II) carbonate
Cu 2 CO 3 (OH) 2	- dimedium dihydroxide carbonate
	Lanthanum (III) nitrate
	- titanium oxide dinitrate

Acidic and basic salts can be converted to medium salts by reaction with the corresponding basic and acidic hydroxide, for example:

Ca (HSO 4) 2 + Ca (OH) = CaSO 4 + 2H 2 O

Ca 2 SO 4 (OH) 2 + H 2 SO 4 = 2CaSO 4 + 2H 2 O

There are also salts containing two different cations: they are often called double salts, eg:

Oxides E x ABOUT at

- products of complete dehydration of hydroxides:

Acid hydroxides

(H 2 SO 4, H 2 CO 3) answer acid oxides (SO 3, CO 2), and basic hydroxides(NaOH, Ca (OH) 2) - basic oxides(Na 2 O, CaO ), and the oxidation state of element E does not change on going from hydroxide to oxide. An example of formulas and names of oxides:

Acidic and basic oxides retain the salt-forming properties of the corresponding hydroxides when interacting with hydroxides of opposite properties or with each other:

N 2 O 5 + 2NaOH = 2NaNO 3 + H 2 O

3CaO + 2H 3 PO 4 = Ca 3 (PO 4) 2 + 3H 2 O

La 2 O 3 + 3SO 3 = La 2 (SO 4) 3

Amphotericity

hydroxides and oxides - a chemical property consisting in the formation of two series of salts by them, for example, for hydroxide and aluminum oxide:

(a) 2Al (OH) 3 + 3SO 3 = Al 2 (SO 4) 3 + 3H 2 O

Al 2 O 3 + 3H 2 SO 4 = Al 2 (SO 4) 3 + 3H 2 O

(b) 2Al (OH) 3 + Na 2 O = 2NaAlO 2 + 3H 2 O

Al 2 O 3 + 2NaOH = 2NaAlO 2 + H 2 O

So, hydroxide and aluminum oxide in reactions (a) exhibit the properties major hydroxides and oxides, i.e. react with acidic hydroxides and oxide to form the corresponding salt - aluminum sulfate

Al 2 (SO 4) 3 , while in reactions (b) they also exhibit the properties acidic hydroxides and oxides, i.e. react with basic hydroxide and oxide, forming a salt - dioxoaluminate ( III) sodium NaAlO 2 ... In the first case, the element aluminum exhibits the property of a metal and is part of the electropositive component ( Al 3+), in the second is a property of a non-metal and is part of the electronegative component of the salt formula ( AlO 2 -).

If these reactions take place in an aqueous solution, then the composition of the formed salts changes, but the presence of aluminum in the cation and anion remains:

2Al (OH) 3 + 3H 2 SO 4 = 2 (SO 4) 3

Al (OH) 3 + NaOH = Na

Here, square brackets denote complex ions

3+ - cation of hexaaquaaluminum (III), - - tetrahydroxoaluminate (III) -ion.

Elements that exhibit metallic and non-metallic properties in compounds are called amphoteric, these include elements of the A-groups of the Periodic Table -

Be, Al, Ga, Ge, Sn, Pb, Sb, Bi, Po and others, as well as most of the elements of B-groups - Cr, Mn, Fe, Zn, Cd, Au and others. Amphoteric oxides are called the same as the main ones, for example:

Amphoteric hydroxides (if the oxidation state of the element exceeds +

II ) can be in ortho - or (and) meta - form. Here are some examples of amphoteric hydroxides:

Amphoteric oxides do not always correspond to amphoteric hydroxides, since when trying to obtain the latter, hydrated oxides are formed, for example:

If the amphoteric element in the compounds corresponds to several oxidation states, then the amphotericity of the corresponding oxides and hydroxides (and, consequently, the amphotericity of the element itself) will be expressed in different ways. For low oxidation states, hydroxides and oxides have a predominance of basic properties, and the element itself has metallic properties, so it is almost always included in the composition of cations. For high oxidation states, on the contrary, acidic properties predominate in hydroxides and oxides, and non-metallic properties in the element itself, therefore it is almost always included in the composition of anions. So, for manganese oxide and hydroxide (

II ) dominate the basic properties, and manganese itself is part of the cations of the type [ Mn (H 2 O) 6] 2+ , while manganese oxide and hydroxide ( Vii ), acidic properties dominate, and manganese itself is part of the anion of the type MnO 4 - ... Amphoteric hydroxides with a large predominance of acidic properties are attributed to formulas and names based on acidic hydroxides, for example, H Mn VII O 4 - permanganic acid.

Thus, the division of elements into metals and non-metals is conditional; between elements (

Na, K, Ca, Ba and others) with purely metal and elements ( F, O, N, Cl, S, C and others) with purely non-metallic properties, there is a large group of elements with amphoteric properties.

An extensive type of inorganic complex substances is binary compounds. These include, first of all, all two-element compounds (except for basic, acidic and amphoteric oxides), for example

H 2 O, KBr, H 2 S, Cs 2 (S 2), N 2 O, NH 3, HN 3, CaC 2, SiH 4 ... The electropositive and electronegative constituents of the formulas of these compounds include individual atoms or linked groups of atoms of one element.

Multi-element substances, in the formulas of which one of the constituents contains atoms of several elements unconnected with each other, as well as single-element or multi-element groups of atoms (except for hydroxides and salts), are considered as binary compounds, for example

CSO, IO 2 F 3, SBrO 2 F, CrO (O 2) 2, PSI 3, (CaTi) O 3, (FeCu) S 2, Hg (CN) 2, (PF 3) 2 O, VCl 2 (NH 2). So CSO can be thought of as a connection CS 2 , in which one sulfur atom is replaced by an oxygen atom.

Names binary compounds are built according to the usual nomenclature rules, for example:

OF 2 - oxygen difluoride	K 2 O 2 - potassium peroxide
HgCl 2 - mercury (II) chloride	Na 2 S - sodium sulfide
Hg 2 Cl 2 - dichloride dirtuti	Mg 3 N 2 - magnesium nitride
SBr 2 O - sulfur oxide dibromide	NH 4 Br - ammonium bromide
N 2 O - dinitrogen oxide	Pb (N 3) 2 - lead (II) azide
NO 2 - nitrogen dioxide	CaC 2 - calcium acetylenide

For some binary compounds, special names are used, the list of which was given earlier.

Chemical properties binary compounds are quite diverse, therefore they are often divided into groups by the name of the anions, i.e. halides, chalcogenides, nitrides, carbides, hydrides, etc. are considered separately. Among binary compounds, there are also those that have some features of other types of inorganic substances. So, connections

CO, NO, NO 2, and (Fe II Fe 2 III) O 4 , the names of which are constructed using the word oxide, cannot be classified as oxides (acidic, basic, amphoteric). Carbon monoxide CO, nitrogen monoxide NO and nitrogen dioxide NO 2 do not have corresponding acidic hydroxides (although these oxides are formed by non-metals C and N ), they do not form salts, the composition of the anions of which would include C atoms II, N II and N IV. Double oxide (Fe II Fe 2 III) O 4 - oxide of diiron (III) -iron (II ) although it contains atoms of an amphoteric element - iron - in the electropositive component, but in two different oxidation states, as a result of which, when interacting with acidic hydroxides, it forms not one, but two different salts.

Binary compounds such as

AgF, KBr, Na 2 S, Ba (HS) 2, NaCN, NH 4 Cl, and Pb (N 3) 2 , are built, like salts, from real cations and anions, therefore they are called salty binary compounds (or just salts). They can be considered as products of the substitution of hydrogen atoms in compounds H F, H Cl, H Br, H 2 S, H CN and H N 3 ... The latter in aqueous solution have an acidic function, and therefore their solutions are called acids, for example H F (aqua) - hydrofluoric acid, H 2 S (aqua) - hydrogen sulfide acid. However, they do not belong to the type of acidic hydroxides, and their derivatives are salts within the framework of the classification of inorganic substances.

For the elements included in the periodic system (PS) of elements D.I. Mendeleev, it is allowed to use the following group names, reflecting, as a rule, the general properties of elements and simple substances. For items main subgroups in the short-period PS version

or 1-2 and 13-18 groups in the long-period (modern) version of the PS

• alkaline metals (1st or IA group): (H), Li, Na, K, Rb, Cs, Fr;
• alkaline earth(except Mg) metals (2nd or IIAg group): Be, Mg, Ca, Sr, Ba, Ra;
• the elements boron subgroups(13th or IIIA group), metals (boron feed), do not have a special name: B, Al, Ga, In, Ti;
• the elements subgroups of carbon(14th or IVA group) or crystallogenes: C, Si, Ge, Sn, Pb;
• the elements nitrogen subgroups(15th or VA group), outdated name pnicogensand its derivative -pnictids: N, P, As, Sb, Bi;
  
• the elements oxygen subgroups(16 or VIA group) orchalcogenes ,
• halogens(17th or VIIA group),
• noble or inertgases (18th or VIIIA group)

For items side subgroups:

• lanthanides(La - Lu),
• actinides(Ac - Lr) (it is not recommended to use the names of lanthanides and actinides);
• rare earth metals(3rd or IIIB group, except for actinides);
• iron family(Fe, Co, Ni);
• family of platinum or platinum metals(Ru, Rh, Pd, Os, Ir, Pt);
• noble metals(Au, Ag + platinum: Ru, Rh, Pd, Os, Ir, Pt)
• transition elements(d and f-elements, that is, all elements of the secondary subgroups).

Simple substances are usually called the same as the corresponding elements. Only allotropic modifications carbon (diamond, graphite, carbyne, fullerenes) and the second modification of oxygen (ozone). With names allotropic modifications other elements usually indicate its brief physical characteristics (white, red, black phosphorus, crystalline and plastic sulfur, gray and white tin, etc.).

The elements oxygen, nitrogen, carbon and sulfur in compounds with metals or with less electronegative non-metals can form anions not only in their characteristic negative oxidation states ($ O ^ (2-), S ^ (2-), N ^ (3- ), C ^ (4 -) $, but also ions, in which the oxidation state of an element depends on the number of atoms in the "bridge" structures. The oxidation state of carbon in organic compounds is determined by special methods (see the topic "Determination of the oxidation state of carbon"). For example, the element oxygen can form peroxide and over-peroxide ions, in which oxygen atoms form "oxygen bridges" -OO- or -OOO-. Such anions have their own names: $ (O_2) ^ (2 -) $ - peroxide; $ (O_2) ^ - $ - superoxide; $ (O_3) ^ - $ - ozonide; $ (N_3) ^ - $ - azide; $ (C_2) ^ (2 -) $ - acetylenide; $ (S_2) ^ (2- ) $ - disulfide; $ (Sn) ^ (2 -) $ - polysulfide.

The names of some stable anions, consisting of atoms of more than one element, traditionally also have the endings -id: $ (OH) ^ - $ - hydroxide; $ (CN) ^ - $ - cyanide; $ (CN_2) ^ (2 -) $ - cyanamide; $ (NH_2) ^ - $ - amide; $ (NH) ^ (2 -) $ - imide; $ (SCN) ^ - $ - thiocyanate.

CLASSIFICATION OF INORGANIC SUBSTANCES

General principles for the classification of inorganic substances are presented in the diagram. Based on this classification, all inorganic substances can be subdivided into simple and complex ones.

Definition

Simple substances consist of atoms of the same elements and are subdivided into metals, non-metals and inert gases.

Complex substances consist of atoms of different elements chemically bonded to each other.

In turn, on the basis of common properties, complex inorganic substances can be conditionally divided into four main classes: binary compounds, oxides, hydroxides, and salts.

The classification and nomenclature of binary compounds is discussed in detail in the topic "Binary compounds".

CLASSIFICATION AND FEATURES OF THE PROPERTIES OF OXIDES

Definition

Oxides are called binary chemical compounds consisting of the elements metals or non-metals and oxygen. Or, in other words, oxides are complex substances composed of two elements, one of which is oxygen.

The classification of oxides is based on the chemical properties of the compounds due to chemical structure(that is, the type of bonds formed and the type of crystal lattice, structure and electronic characteristics of the elements).

By physical properties oxides differ state of aggregation, melting and boiling points, color, odor, solubility in water.

By aggregate state oxides are:

• solid (all metal oxides, silicon oxide, phosphorus oxide),
• liquid (water $ H_2O $),
• gaseous (almost all other oxides of non-metals).

According to their chemical properties, oxides are divided into non-salt-forming and salt-forming.

Definition

Salt-forming are oxides capable of forming hydroxides when combined with water.

The latter, in turn, can exhibit the properties of acids, bases, or have amphoteric properties. Therefore, salt-forming oxides are usually divided into basic, acidic and amphoteric.

CLASSIFICATION of acids and bases

From your basic chemistry course, you are familiar with the following definitions of acids and bases:

Definition

Acids are complex substances consisting of hydrogen atoms that can be replaced by metal atoms, and acid residues. The general formula of acids: $ H_x (Ac) ^ (- n) $, where Ac is the acid residue (acid is the English acid), x is the number of hydrogen atoms, n is the oxidation state of the acid residue. In acids, x = n.

Definition

Foundations(hydroxides) are complex substances consisting of metal atoms and one or more hydroxyl groups (-OH). General base formula: $ M ^ (+ n) (OH) _x $, where n is the oxidation state of the metal, x is the number of hydroxyl groups. n = x.

It should be noted that both bases and acids belong to the class of hydroxides, since they contain hydroxo groups (-OH). Therefore, acids are also called acidic hydroxides, and bases are called basic hydroxides.

Acid-base interactions are extremely common in nature and are widely used in scientific and industrial practice... The theory of acids and bases is a set of fundamental physical and chemical concepts that describe the nature and properties of acids and bases. In addition to the usual definition of 8th grade, there are other theories:

Theory	Content	Examples of
Arrhenius' theory of electrolytic dissociation	Acids are substances that form ions in an aqueous solution - hydrated hydrogen cations $ H ^ + $ (hydronium ions $ H_3O $) and anions of an acid residue, or in other words, these are electrolytes dissociating into hydrogen cations and anions of an acid residue. Foundations- complex electrolyte substances that dissociate to form a hydroxide ion and a metal cation.	$ NaOH \ Leftrightarrow Na ^ + + OH ^ - $ base $ HNO_3 \ Leftrightarrow H ^ + + NO_3 ^ - $ acid
Bronsted's protolithic theory	Acids are complex substances that, as a result of heterolytic rupture, give up a particle with a positive charge - a hydrogen proton (Bronsted acid) Base is a chemical compound capable of forming covalent bond with proton (Brønsted base)	$ HCl + NH_3 = NH_4 ^ + + Cl ^ - $ to-that main to-that main.
Lewis theory	Acid- a molecule or ion with vacant electron orbitals, which is an acceptor of an electron pair (Lewis acid) Base is a chemical compound capable of forming a covalent bond with the vacant orbital of another chemical compound

This topic is described in more detail in the section "Modern concepts of the structure and properties of acids and bases".

Classification of acids

is carried out according to the following formal criteria:

1. by basicity, that is, the number of hydrogen atoms: one- ($ HCl $), two- ($ H_2S $) and tri-basic ($ H_3PO_4 $);

2. by the presence of oxygen atoms: oxygenated ($ H_2CO_3 $) and oxygen-free (HCL);

3. by strength, that is, the degrees of dissociation: strong ($ HCl, HNO_3, H_2SO_4, HClO_4 $, etc.), weak ($ ​​H_2S, H_2CO_3, CH_3COOH $, etc.)

4. by sustainability: y persistent ($ H_2SO_4 $); unstable ($ H_2CO_3 $).

5. by belonging to the classes of chemical compounds: inorganic (HBr); organic ($ HCOOH, CH_3COOH $);

6.volatility: volatile ($ HNO_3, H_2S, HCl $); non-volatile ($ H_2SO_4 $);

7. by solubility in water: soluble ($ H_2SO_4 $); insoluble ($ H_2SiO_3 $);

Base classification

is carried out according to the following formal criteria::

1. by acidity(the number of hydroxyl groups): one-acid (NaOH), two-acid ($ Ca (OH) _2 $), tri-acid ($ Al (OH) _3 $)

2. by solubility: alkalis or soluble bases ($ KOH, NaOH $), insoluble ($ Mg (OH) _2, Cu (OH) _2 $)

3. by strength(degrees of dissociation): strong (NaOH), weak ($ ​​Cu (OH) _2 $)

** Do not confuse the strength of the base with its solubility. For example, calcium hydroxide is a strong base, although its solubility in water is not great. In this case, the strong base (alkali) is that part of calcium hydroxide that is dissolved in water.

AMPHOTERIC HYDROXIDES

Definition

Amphoteric hydroxides are complex substances that exhibit both the properties of acids and the properties of bases.

The formula for amphoteric hydroxides can be written both as an acid and as a base, for example: aluminum hydroxide can be written as a base as $ Al (OH) _3 $. If we count the total number of hydrogen and oxygen atoms, then we can write: $ H_3ALO_3 $ or the simplest formula- $ HAlO_2 $.

Amphoteric oxides and hydroxides are formed by amphoteric elements. Remember! Metalloid elements exhibit amphoteric properties: Al, Zn, B, Be, Fe (III), Cr (III) and some other transitional elements with different oxidation states and located on the amphoteric diagonal in the PS (see the topic "Periodic table, as a conditional notation periodic law Metals of A ‑ groups, forming a diagonal of amphotericity in the Periodic Table Be ‑ Al ‑ Ge ‑ Sb ‑ Po, as well as adjacent metals (Ga, In, Tl, Sn, Pb, Bi) do not exhibit typically metallic properties.

The manifestation of duality (amphotericity) of properties, both metallic (basic) and non-metallic, is due to the nature of the chemical bond.

CLASSIFICATION AND FEATURES OF SALTS PROPERTIES

The determination of salts, as well as the determination of acids and bases, has several options. In the 8th grade school course, the definition of salts is as follows:

Definition

Salts - these are complex substances consisting of metal cations (ammonium ion) and anions of acid residues. The general formula of the salts is: $ M ^ (+ n) _xAc ^ (m -) _ y $, where n, m are the oxidation states of the metal and acid residue, x, y are the number of metal atoms and acid residue, respectively. m = x and n = y

This definition refers to average salts that are formed as a result of a neutralization reaction between an acid and a base, that is, can be obtained by the interaction of acids and bases with the release of water. Therefore, a more accurate definition of medium salts:

Definition

Medium salts are products of complete replacement of hydrogen atoms in an acid molecule by metal atoms, or complete replacement of hydroxo groups in a base molecule with acid residues.

From the point of view of theory electrolytic dissociation(TED):

Salt are complex substances that dissociate in aqueous solutions into metal cations and anions of acid residues.

The International Union of Pure and Applied Chemistry (IUPAC) defines salts as chemical compounds composed of cations and anions.

Thus, the classification of salts can be carried out:

1.by solubility: soluble, slightly soluble and insoluble (you can determine which group the salt belongs to by the solubility table)

2. by the degree of substitution of hydrogen ions and hydroxyl groups: medium, sour, basic, double, mixed. The topic is discussed in more detail in the "Classification and nomenclature of salts" section.

The table shows examples and definitions of acidic and basic salts.

average	sour	the main	double
Product of complete replacement of acid hydrogen by metal	Product of incomplete substitution of acid for metal hydrogen (known only for polybasic acids)	The product of incomplete substitution of the hydroxyl groups of the base by an acidic residue (known only for polyacid bases)	Product of complete replacement of hydrogen atoms of a di- or polybasic acid with two different metals
Na $ _2 $ SO $ _4 $ sodium sulfate CuCl $ _2 $ copper (II) chloride $ Ca_3 (PO_4) _2 $ calcium orthophosphate	sodium hydrogen sulfate CaHPO $ _4 $ calcium hydrogen phosphate Ca (H $ _2 $ PO $ _4 $) $ _ 2 $ calcium dihydrogen phosphate	copper (II) hydroxychloride Ca $ _5 $ (PO $ _4 $) $ _ 3 $ (OH) calcium hydroxyorthophosphate	$ NaKCO_3 $ potassium sodium carbonate aluminum potassium sulfate

A separate large class is made up of complex salts, which are complex compounds.

Definition

Complex compounds or coordination compounds- particles (neutral molecules or ions) that are formed as a result of attachment to a given ion (or atom), called complexing agent, neutral molecules or other ions called ligands.

Inner sphere a complex compound - a central atom with ligands bound to it, that is, in fact, a complex particle.

Outer sphere complex compound - the rest of the particles associated with a complex particle by ionic or intermolecular bonds, including hydrogen.

For example, consider the structure of the complex salt of $ K_3 $ - potassium hexacyanoferrate (III).

The inner sphere is formed by an iron (III) ion, therefore it is a complexing agent with an oxidation state of +3. Six $ CN ^ - $ ions are coordinated around this ion. These are ligands, the coordination number is six. The total charge of the inner sphere is: (+3) + (-1) x6 = (- 3).

The outer sphere is formed by potassium cations $ K ^ + $. In accordance with the charge of the inner sphere, equal to (-3), there should be 3 potassium ions in the outer sphere.

Complex salts with an outer sphere in an aqueous solution completely dissociate into a complex low-dissociation cation or anion.

Complex compounds without external sphere insoluble in water (for example, metal carbonyls).