Each element is able to form a simple substance while being in a free state. In this state, the motion of atoms is the same, they are symmetrical. In complex substances, the situation is much more complicated. Chemical bonds are asymmetric in this case, complex covalent bonds are formed in molecules of complex substances .
What is meant by oxidation
There are such compounds in which electrons are distributed as unevenly as possible, i.e. When complex substances are formed, the valence electrons pass from atom to atom. It is this uneven distribution in complex substances called oxidation or oxidation. The charge of an atom in a molecule formed in this case 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 the acceptance by the atom of an element of several electrons, respectively, the positive and negative degrees of oxidation of the chemical elements (E + or E - ) are formed. For example, writing K + 1 means that the potassium atom has given up one electron. In any organic compound, the central place is occupied by carbon atoms. The valence of this element corresponds to the 4th in any compound, but in different compounds the degree of oxidation of carbon will be different, it will be -2, +2, ± 4. Such a nature of a different valence and oxidation degree is observed in practically any compound.
Determination of oxidation state
To correctly determine the degree of oxidation, you need to know the underlying postulates. Metals are not capable of having a minus degree, but there are rare exceptions when the metal forms compounds with the metal. In the periodic system, the number of the atom group corresponds to the maximum possible degree of oxidation: carbon, oxygen, hydrogen and any other element. The electronegative atom, when displaced towards one another by an electron, receives a charge of -1, two electrons -2, and so on. This rule does not apply to the same atoms. For example, for the H-H bond, it will be equal to 0. The C-H = -1 bond. The degree of oxidation of carbon in the C-O bond is + 2. The metals of the first and second groups of the Mendeleyev system and fluorine (-1) have the same degree value. In hydrogen, this degree is practically in all compounds equal to +1, except for hydrides in which it is -1. For elements having a non-constant degree, it can be calculated by knowing the connection formula. The basic rule that states that the sum of powers in any molecule is 0.
Example of calculating the oxidation state
Consider the calculation of the degree of oxidation by the example of carbon in the compound CH3CL . Let's take the initial data: the degree of hydrogen is +1, for chlorine -1. For convenience, in the calculation of x we will assume the degree of oxidation of carbon. Then, for CH3CL there will be an equation x + 3 * (+ 1) + (- 1) = 0. By performing simple arithmetic operations, it can be determined that the oxidation state of carbon will be +2. In this way, you can perform calculations for any element in a compound.