The chemistry for each school student begins with Mendeleyev's table and fundamental laws. And already only then, having understood for itself what is studied by this difficult science, it is possible to start drawing up chemical formulas. For competent record of connection it is necessary to know the valency of the atoms making it.
Instruction
1. Valency – ability of some atoms to hold near itself a certain number of others and is expressed it by number of the withheld atoms. That is, the element is stronger, the more it has a valency.
2. For an example it is possible to use two substances – HCl and H2O. These are well-known all hydrochloric acid and water. The first substance contains one atom of hydrogen (H) and one atom of chlorine (Cl). It says about that, in this connection they form one communication, that is hold near themselves one atom. Therefore, valency and one, and another is equal to 1. It is also simple to determine the valency of the elements making a water molecule. It contains two atoms of hydrogen and one atom of oxygen. Therefore, atom of oxygen formed two communications for accession of two water childbirth, and they, in turn, on one communication. Means, the valency of oxygen is equal 2, and hydrogen – 1.
3. But sometimes it is necessary to face substances more difficult in structure and to properties of the atoms making them. There are two types of elements: from a constant (oxygen, hydrogen, etc.) and changeable valency. At atoms of the second type this number depends on connection which part they are. It is possible to give properties of other components of substance as an example.
4. Remember the rule: the work of amount of atoms on the valency of one element in connection has to coincide with the same work for other element. It can be checked again having addressed a molecule of water (H2O): 2 (amount of hydrogen) * 1 (its valency) = 21 (amount of oxygen) * 2 (its valency) = 22 = 2 – is meant by everything is defined truly.
5. Now check this algorithm on more complex substance, for example, of N2O5 – nitrogen oxide. Earlier it was specified that oxygen has the constant valency 2 therefore it is possible to work out the equation: 2 (oxygen valency) * 5 (its quantity) = X (unknown valency of nitrogen) * 2 (its quantity) By simple arithmetic calculations can define that nitrogen valency as a part of this connection is equal to 5.