Each element is able to form a simple substance, being in a free state. In this state, the movement of atoms occurs in the same way, they are symmetrical. In complex substances, the situation is much more complicated. Chemical bonds in this case are asymmetric, complex covalent bonds are formed in the molecules of complex substances.
What is meant by oxidation
There are compounds in which electrons are distributed as unevenly as possible, i.e. in the formation of complex substances, valence electrons pass from atom to atom.
It is this uneven distribution in complex substances that is called oxidation or oxidation. The resulting charge of an atom in a 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 giving or receiving an atom of an element of several electrons, a positive and negative oxidation state of chemical elements is formed, respectively (E+ or E-). For example, the entry K+1means that the potassium atom gaveone electron. In any organic compound, carbon atoms occupy a central place. The valency of this element corresponds to the 4th in any compound, however, in different compounds, the oxidation state of carbon will be different, it will be equal to –2, +2, ±4. This nature of different values of valency and oxidation state is observed in almost any compound.
Determination of oxidation state
In order to correctly determine the degree of oxidation, you need to know the fundamental postulates.
Metals are not capable of having a negative degree, however, there are rare exceptions when metal forms compounds with metal. In the periodic system, the group number of an atom corresponds to the maximum possible oxidation state: carbon, oxygen, hydrogen, and any other element. When an electronegative atom is shifted towards another atom, one electron receives a charge of -1, two electrons -2, etc. This rule does not work for the same atoms. For example, for the H-H bond, it will be equal to 0. The C-H bond \u003d -1. The degree of oxidation of carbon in the connection C-O \u003d + 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 that have a non-constant degree, it can be calculated by knowing the formula of the compound. The basic rule that says that the sum of powers in any molecule is 0.
Exampleoxidation state calculation
Let's 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, that of chlorine is -1. For convenience, in the calculation of x we will consider the degree of oxidation of carbon. Then, for CH3CL the equation x+3(+1)+(-1)=0 will take place. Having performed simple arithmetic operations, it can be determined that the oxidation state of carbon will be +2. In this way, calculations can be made for any element in a complex connection.
