Oxidation level - though conditional, but quite useful concept. We learn to calculate oxidation levels of elements.
Instruction
1. Oxidation level is the conditional charge of atoms expected from the assumption that all chemical bonds in a molecule - ionic, and the electronic density of each communication is completely displaced to more electronegative element. It is the conditional size deprived of physical sense. Its value consists in use for finding of stoichiometric coefficients of reactions, for classification of substances, including complex. Also it is applied to drawing up the chemical nomenclature and the description of properties of substances. On the letter the oxidation level is specified in a type of the Arab figures with a plus or minus over the corresponding element in a molecular formula of connection.
2. Several general rules: Element oxidation level is equal in simple substances to zero. Total oxidation level at complex substances is also equal to zero - it the rule is one of the oxidation levels of components, main at calculations. At the elements which are a part of complex substances oxidation level is expressed by an integer with rare exception. Hydrogen has oxidation level +1 (except for hydrides - in them-1), oxygen-2 (except for peroxides (-1) and connections with fluorine (+2)). Some elements have one, constant oxidation level: +1 lithium, potassium, sodium, rubidium, caesium, silver; The +2nd beryllium, magnesium, calcium, strontium, zinc, cadmium, barium; The +3rd aluminum, pine forest;-1 fluorine. Calculation of oxidation level goes taking into account the indexes standing at the corresponding elements in connection.
3. Let's review an example. H2SO4 is sulfuric acid. Let's use the rules stated above: 2*1+ x +4 * (-2) =0.h - sulfur oxidation level, we do not know it yet. From the simple linear equation we find it: x =6. Thus, over hydrogen, sulfur and oxygen it is necessary to put down +1 (unit in oxidation levels is usually not written - it is meant therefore instead of +1 and-1 it is accepted to write simply + and-), +6 and-2, respectively.