Amongst the various types of solids - metallic, ionic, covalent - the molecular solid is a type that is differentiated from the rest based on its intermolecular attractive strength.
A molecular solid is composed of distinct, unconnected molecules that are held together by weak van der Waals forces or Hydrogen bonds rather than stronger ionic or covalent bonds.
Due to Van der Waals’ weaker interactions, the molecular solids are soft, volatile and have lower melting and boiling points. However, larger molecules are less volatile and have higher melting points since the increase in the number of atoms increase the dispersion forces. Still most molecular solids will melt below 300 oC, a significant decline when compared to metals, network covalent and ionic solids (around 1000 0C).
Examples of molecular solids are Argon, Water, Iodine, Naphthalene, Nicotine, Caffeine. Evidently, the molecular solids can be composed of mono-atoms, di-atoms, or polyatomic molecules.
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