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Crystalline solids are solids whose atoms, ions, or molecules are arranged in an orderly, geometric, three-dimensional structure; can be classified by shape or composition or class of solids that have regular or nearly-regular crystalline structures. This means that the atoms in these solids are arranged in an orderly manner. Solids are divided into two types:
These two are differentiated on the basis of their physical properties. Crystalline solids are of a definite shape and have a definite melting point, while amorphous solid have no definite shape and melt at a range of temperatures. Crystalline solids are also known for their anisotropic nature, whereas amorphous solids are isotropic.
| Crystal | Particles | Attractive Forces | Melting point | Other properties |
|---|---|---|---|---|
| Ionic | Positive and negative ions | Electrostatic attractions | High | Hard, brittle, good electrical conductor in molten state |
| Molecular | Polar molecules | London force and dipole-dipole attraction | Low | Soft, non-conductor or extremely poor conductor of electricity in liquid state |
| Molecular | Non-polar molecules | London force | Low | Soft, non-conductor or extremely poor conductor of electricity in liquid state |
| Network | Atoms | Covalent bonds | Very high | Very hard, non-conductor of electricity |
| Metallic | Positive ions and mobile electrons | Metallic bonds | Fairly high | Hard or soft, malleable and ductile, good electrical conductor |
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