1. Chemical compound complex compounds

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compounds are formed. Thus, one complex passes into another.
Complex compounds are used in many places. Their importance in biology is very great. There is no life without complex compounds.
Hemoglobin is a complex combination of Fe ²⁺ and chlorophyll Mg ²⁺ . Complex compounds can be bases, acids, salts. They also contain non-electrolyte substances.
Bases Acids Salts
[Ag(NH ₃ ) ₂ ]OH H[AuCl ₄ ] [Ni(NH ₃ ) ₄ ]SO ₄
[Cu(NH ₃ ) ₂ ](OH) ₂ H ₂ [SnF ₆ ] Na ₃ [AlF ₆ ]
[Ni(NH ₃ ) ₄ ](OH) ₂ H ₂ [PtCl ₆ ] K ₃ [Fe(CN) ₆ ]
Non-electrolytic substances: [Pt(NH ₃ ) ₄ Cl ₂ ] [Pt(NH ₃ ) ₆ ]Cl ₄
[Ni(CO) ₄ ] [Fe(CO) ₅ ]
The structure of complex compounds was explained in 1898 by the Swedish scientist Alfred Werner in his coordination theory. According to this theory:

1. 
   The central place in the complex compound is occupied by the complex-forming - charged metal atom (cation).
   
2. 
   A complex-forming ion or atom is surrounded by a certain number of anions or neutral molecules bound to it. These anions or molecules are called ligands. Their number is a coordination number. is called
   
3. 
   Complexing agents and ligands form the inner sphere and are enclosed in square brackets.
   
4. 
   Ions that do not enter the inner sphere form the outer sphere.
   

┌─ ─┐
K ⁺ │ CN ^- CN ^- │
K ⁺ │ CN ^- Fe ³⁺ CN ^- │ K ₃ [Fe(CN) ₆ ]
K ⁺ │ CN ^- CN ^- │
└─ ─┘
To write the formula of a complex compound:
1) the charge of the complex-forming ion;
2) charge of ligands;
3) coordination number;
4) outer sphere ions should be known.
Complex-forming ions are mainly ions of d-elements in Mendeleev's periodic system. They are: Ag ¹⁺ , Au ¹⁺ , Au ³⁺ , Cu ²⁺ , Cu ¹⁺ ,
Zn ²⁺ , Cd ²⁺ , Co ²⁺ , Ni ²⁺ , Fe ²⁺ , Fe ³⁺ , Pt ²⁺ , Pt ⁴⁺ , Pd ²⁺ , Pd ⁴⁺ , Al ³⁺ .
As ligands a) molecules with dipole character - H ₂ O, NH ₃ , NO, CO , N ₂ H ₄ , NH ₂ C ₂ H ₄ NH _{2 ,} etc.;

1. 
   b) ions - SN ^- , NO ₂ ^- , Cl ^- , Br ^- , J ^- , OH ^- , CO ₃ ^2- , SO ₄ ^2- ,
   

CH ₃ COO- ^, SO ₃ ^2- , PO ₄ ^3- , CNS- ^, CrO ₄ ^2- ;
For some complexing ions

Coordinate number	2	4	6	8
Ions	Cu ^+ Ag ^+ Hg ^+ Au ^+	Cu ^2+ Zn ^2+ Hg ^2+ Mg ^2+	Al ^3+ Cr ^3+ Fe ^3+ Fe ^2+	Ca ^2+ Ba ^2+ Mg ^2+ Pd ^2+

It can be seen that in most cases the coordination number is 4 and 6.

Specific properties of organic compounds

Unlike organic compounds, organic substances have a number of unique properties. First of all, it is necessary to mention the properties of carbon atoms joining together to form chains and rings, which is not typical of inorganic compounds. This is one of the reasons for the diversity of organic compounds.
In organic molecules, the bonds between atoms are covalent. For this reason, organic substances are usually considered non-electrolytes.
organic substances with simple (primary) S — S and S — H bonds in their molecules react with each other very difficult. or does not react at all.
Organic compounds completely decompose or turn into coal when heated in the range of 400-600°C, and burn in the presence of oxygen. The reason for this is that the bond between carbon atoms is not very strong (355.6 kJ/mol).
The specific properties of the carbon atom are explained by its structure: it has four valence electrons. Carbon atoms share electron pairs with other atoms as well as with each other. In this case, each carbon atom has eight electrons (octets) in its outer shell, four of which are shared by other atoms at the same time.
Organic chemistry usually uses structural formulas because atoms are spatially arranged in a molecule. Structural formulas are the language of organic chemistry.
In structural formulas, a covalent bond is denoted by a hyphen. As in the structural formulas of inorganic substances, each hyphen indicates a common electron pair connecting atoms in a molecule. Empirical and electronic formulas are also used.