Valence - the ability to keep some of the atoms near a certain number of others, and it is expressed in the number of trapped atoms.That is, the stronger element, the greater the valence of .
For example, you can use two substance - HCl and H2O.It is well known to all, hydrochloric acid and water.In the first substance comprises one hydrogen atom (H) and chlorine atom (Cl).This suggests that, in this connection, they form a bond that is held near the atom itself.Therefore, the valence and one, and the other is 1. So just define valence of the elements constituting the water molecule.It contains two hydrogen atoms and one oxygen atom.Consequently, an oxygen atom formed two bonds for a
ttachment of two hydrogens, and they, in turn, by a single bond.So, valence of oxygen is equal to 2, and hydrogen - 1.
But sometimes you have to deal with the substance of more complex in structure and properties of their constituent atoms.There are two types of items: a constant (oxygen, hydrogen, etc.) And unstable valence w.Atoms of the second type is dependent on the number of connections, of which they are part.As an example, sulfur (S).It may have the valence of 2, 4, 6 and sometimes even 8. Determine the ability of elements such as sulfur, to hold other atoms around them, a little harder.To do this, you must know the properties of the other components substance .
Remember the rule: the product of the number of atoms in the valence of one element in the mix must match the same product for another item.This can be checked again turning to the water molecule (H2O):
2 (hydrogen) * 1 (it valence of ) = 2
1 (oxygen) * 2 (his valence of ) = 2
2 = 2 - meansAll is true.
Now check this algorithm is more complex substances, such as, N2O5 - nitrogen oxides.Previously stated that oxygen has a constant valence of 2, so you can make the equation:
2 ( valence of oxygen) * 5 (the amount) = X (unknown valence of nitrogen) * 2 (the amount)
By simple arithmeticcalculations can be determined that valence of nitrogen in the composition of the compound equal to 5.