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11. CRYSTAL LATTICES.
From physics course you know that substances can exist in three modular состояниях:твёрдм, liquid, gaseous. In this paragraph we will consider crystal substances, i.e. the substances which are in solid state. They form crystal lattices.
Crystal lattices of substances are the arranged arrangement of particles (atoms, molecules, ions) in strictly certain points of space. Points razmeshchniya of particles are called nodes of crystal lattice.
Depending on type of the particles located in nodes of crystal lattice, the ikharakter of communication between them is distinguished by 4 types of crystal lattices: ionic, atomic, molecular, metal. Let's treat each of lattices apart in more detail.
| IONIC |
| Ionic call crystal lattices in which nodes there are ions. They are formed by substances with ionic bond. Ionic crystal lattices have salts, some oxides and metal hydroxides. |
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Let's consider structure of crystal of sodium chloride in which nodes there are ions of chlorine and sodium.
Bonds between ions in crystal very strong and steady. Therefore substances with ionic lattice have the high hardness and durability, refractory and is nonvolatile. |
| ATOMIC |
| Atomic call crystal lattices in which nodes there are separate atoms which are connected by very strong covalent linkages. Below the crystal lattice of diamond is shown. |
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In the nature a few substances meet atomic crystal lattice. Boron, silicon, germanium, quartz, diamond concern to them. Substances about the ACRE have high melting temperatures, have the increased hardness. The diamond-hardest natural material. |
| MOLECULAR |
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Molecular call crystal lattices in which nodes molecules are located. Chemical bonds in them covalent, both polar, and unpolar. Bonds in molecules strong, but between communication molecules not strong. The crystal lattice of I2 is given below |
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Substances with μR have small hardness, melt at low temperature, flying, at usual conditions are in gaseous or liquid state |
| METAL |
| Metal call lattices in which nodes there are atoms and ions of metal. |
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Physical properties are characteristic of metals: plasticity, malleability, metallic luster, high electro-and heat conductivity |
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