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A molecular crystal is a crystal whose molecules are held together by weak physical bonding such as van der Waals forces, dipole-dipole bonds, or hydrogen bonding as opposed to chemical bonding like ionic or metallic bonds.

In such a crystal, the constituent particles are molecules. They are formed by covalent bonds between the atoms. If the centre of negative charges and the centre of positive charges coincide in a molecule, it is called a nonpolar molecule. The bond between polar molecules is called a dipole–dipole bond, whereas the bond between nonpolar molecules is called a van der Waals bond. Molecular solids are usually soft, have low melting points and are poor conductors of electricity.

Examples include ice, iodine, solid carbon dioxide (dry ice), rock candy (sucrose), H₂O.

It is very soft compared to covalent and ionic. It is bad conductor and soluble in polar solvent ( as well as insoluble in some solvents ). It's heat of vapourisation is 23.55 (NH₃)

[edit] External links

• Types of Crystals – About.com

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