Oxidation level — the characteristic of elements which is often found in textbooks of chemistry. There is a large number of the tasks directed to definition of this degree and many of them cause in school students and students of difficulty. But, following a certain algorithm, these difficulties it is possible to avoid.
It is required to you
- - Periodic Table (D.I. Mendeleyev's table).
Instruction
1. Remember one general rule: oxidation level of any element is equal in simple substance to zero (examples of simple substances: Na, Mg, Al — i.e. the substances consisting of atoms of one element). For definition oxidation levelsof difficult of substance in the beginning just write down it, without losing indexes — the figures standing in the right lower part near an element symbol. Sulfuric acid — H2SO4 will be an example.
2. Further open D.I. Mendeleyev's table and find the oxidation level of the most left element in your substance — hydrogen in case of this example. By the existing rule its oxidation level will be always positive, and she registers with the sign "+" as it holds extreme left position in record of a formula of substance. To define numerical value of oxidation level, pay attention to arrangement of an element concerning groups. Hydrogen is in the first group, therefore, its oxidation level +1, but as in sulfuric acid two atoms of hydrogen (it shows us the index), over its symbol write +2.
3. After that determine the oxidation level of the most right element in record — oxygen in this case. Its conditional charge (or oxidation level) will be always negative as it holds the right position in record of substance. It ruled fairly in all cases. The numerical value of the right element is in result of subtraction from number of its group of number 8. In this case the oxidation level of oxygen is equal-2 (6-8=-2), considering the index —-8.
4. To find a conditional charge of atom of the third element, use the rule — the sum of oxidation levels of all elements has to be equal to zero. Means, the conditional charge of atom of oxygen will be equal in substance to +6: (+2) (+6) (-8) =0. After that write down +6 over a sulfur symbol.