The crystal is a body which particles (atoms, ions, molecules) are located not in chaotic, and in strictly certain order. This order periodically repeats, forming kind of imagined "lattice". It is considered to be that there are four types of crystal lattices: metal, ionic, atomic and molecular. And how it is possible to define what type of a crystal lattice has any given substance?
Instruction
1. As it is easily possible to guess from the naming, the metal type of a lattice meets at metals. These substances are characterized, as a rule, by high temperature of melting, metal gloss, hardness, are good conductors of electric current. Remember that in knots of lattices of this kind there are either neutral atoms or positively charged ions. In intervals between knots – electrons which migration provides high electric conductance of similar substances.
2. Ionic type of a crystal lattice. It is necessary to remember that it is inherent in oxides and salts. A characteristic example – crystals all of the known table salt, sodium chloride. In knots of such lattices positively also negatively charged ions alternately alternate. Such substances, as a rule, refractory, with small volatility. As it is easy to guess, they have ionic type of a chemical bond.
3. The atomic type of a crystal lattice is inherent in simple substances – nonmetals which under normal conditions represent themselves solid bodies. For example, to sulfur, phosphorus, carbon. In knots of such lattices there are neutral atoms connected with each other by a covalent chemical bond. The refractoriness, insolubility in water is peculiar to such substances. Some (for example, to carbon in the form of diamond) – exclusively high hardness.
4. At last, the last type of a lattice - molecular. It meets at the substances which are under normal conditions in a liquid or gaseous look. As again it is easily possible to understand from the name, in knots of such lattices – molecules. They can be as an unpolar look (at plain gases of Cl2 type, O2), and a polar look (the most known example – H2O water). Substances with such type of a lattice do not carry current, letuch, have low temperatures of melting.
5. So that with confidence to define what type of a crystal lattice has any given substance, you should understand to what class of substances it belongs and what physical and chemical properties has.