Each element is able to form a simple substance, being in a free state. In this state, the motion of atoms occurs identically, they are symmetrical. In complex substances, the situation is much more complicated. Chemical bonds in this case are asymmetric, complex covalent bonds form in the molecules of complex substances .
What is meant by oxidation
There are compounds in which the electrons are distributed as unevenly as possible, i.e. during the formation of complex substances, valence electrons pass from atom to atom.
It is such an uneven distribution in complex substances called oxidation or oxidation. The atomic charge formed in this case in the molecule is called the degree of oxidation of the elements. Depending on the nature of the transition of electrons from atom to atom, a negative or positive degree is distinguished. In the case of recoil or acceptance by an atom of an element of several electrons, a positive and negative oxidation state of chemical elements (E + or E
- )
is formed, respectively. For example, writing K
+1 means that the potassium atom gave away one electron. In any
organic compound, the central place is occupied by carbon atoms. The valency of this element corresponds to the 4th in any compound, however, in different compounds the degree of carbon oxidation will be different, it will be โ2, +2, ยฑ 4. This nature of different values โโof valency and oxidation state is observed in almost any compound.
Determination of oxidation state
To correctly determine the degree of oxidation, it is necessary to know the fundamental postulates.
Metals are not able to have a negative degree, however, there are rare exceptions when the metal forms compounds with the metal. In a periodic system, the atomic group number corresponds to the maximum possible oxidation state: carbon, oxygen, hydrogen, and any other element. An electronegative atom when displaced to the side of another atom of one electron receives a charge of -1, two electrons of -2, etc. This rule does not apply to the same atoms. For example, at the H-H bond it will be 0. The C-H bond is -1. The degree of oxidation of carbon in the bond C โ O = + 2. The metals of the first and second groups of the Mendeleev system and fluorine (-1) have the same degree value. In hydrogen, this degree in almost all compounds is +1, with the exception of hydrides in which it is -1. For elements with a variable degree, it can be calculated by knowing the compound formula. The basic rule that states that the sum of the degrees in any molecule is 0.
Example of calculating the degree of oxidation
Let us consider the calculation of the oxidation state using the example of carbon in the compound CH3CL . Let's take the initial data: the degree of hydrogen is +1, and that of chlorine is -1. For convenience, in the calculation of x we โโwill consider the degree of carbon oxidation. Then, for CH3CL, the equation x + 3 * (+ 1) + (- 1) = 0 will hold. After performing simple arithmetic, it can be determined that the degree of oxidation of carbon will be +2. In this way, you can make calculations for any element in a complex connection.