There is the whole class of complex chemicals - complex connections. Are their part: the central atom – a kompleksoobrazovatel, the internal and external sphere. The internal sphere can consist both of ions, and of molecules and also of a combination of ions and molecules. Both the positively charged cation, and negatively charged anion can be the external sphere. Kompleksoobrazovatel together with the internal sphere form a so-called complex ion.
Instruction
1. First of all write an exact formula of complex connection. Here, for example, yellow blood salt – potassium hexacyanoferrate. Its formula: K4 [Fe(CN)6].
2. Define structure of a complex ion. In this case it is an ion [Fe(CN)6] which size and the sign of a charge you should determine. And four ions of potassium make the external sphere of this connection.
3. Now you will be helped by one of the main governed chemistry saying: any molecule electrically is neutral. That is the total charge of a molecule of hexacyanoferrate of potassium is also equal in this specific case to zero. And it can be only when the charge of a complex ion [Fe(CN)6] is counterbalanced by a total charge of four ions of potassium which are in the external sphere. That is a charge of a complex ion same on dimension, but with the opposite sign.
4. Look in Mendeleyev's table. Potassium – one of the most active metals, it concedes only to the fellows on the first main group of the table – to rubidium, caesium and France. Therefore, in comparison with other elements which are a part of this connection – iron (Fe), carbon (C) and nitrogen (N), potassium, certainly, the most electropositive. That is it will not attract to itself(himself) the general electronic density of a molecule, and to push away her from itself(himself). It is quite explainable, at potassium at the external electronic level only one electron, and it is much easier for it to give it (that the previous level at which eight electrons, became steady), than to attract still whole seven.
5. Thus, each atom of potassium, forming a chemical bond in this molecule, gave on one electron and will turn, respectively, into an ion with a positive charge +1. Such ions four, therefore, the total charge of the external sphere is equal to +4. And that the molecule was neutral, the charge-4 has to counterbalance it. Here and answer to the question posed.