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Types
of Crystals
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Solid crystals can be divided into four categories. 1) Metallic crystals 2) Ionic crystals 3) Covalent crystals 4) Molecular crystals 1) Metallic Crystals In metallic crystals, atoms are joined together by metallic bond. Metallic crystals are very hard. · They have high melting point and boiling point · They have shiny surface · They conduct electricity and heat · They are ductile .They are malleable
2) Ionic Crystals · Solids that contain ionic bond in their structure consist of ionic crystals. · In ionic crystals, oppositively charged ions are joined together by strong electrostatic forces · They are hard substances · They have high melting and boiling point. · They posses ionic bond · They conduct electricity in molten state and in the form of solution. · They are brittle · They are not ductile· They can not be drawn into sheets |
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3) Covalent Crystals · Solid substances in which atoms are held together by covalent bond are known as covalent crystals. · These crystals are very stable For example: Diamond Graphite 4) Molecular Crystals: In molecular crystals, molecules are joined together by weak Vander Wall forces. These substances have low melting point and boiling point. Generally they are volatile (evaporates) |
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