UNIT 3.2 PROPERTIES OF SOLIDS

PROPERTIES OF SOLIDS

Melting point and boiling point:

The stronger the intermolecular forces, the higher the melting and boiling points.  

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Ions, ionic solids tend to have strong interactions and therefore high melting and boiling points (low vapor pressure).  But tend to be brittle due to repulsion of like charges when one layer slides against another.  They conduct electricity only when melted or dissolved in water or another solvent.  

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Covalent network solids (non-metals) are atoms covalent in 3 or 2 dimension networks.  Graphite is in layers and is soft as each layer slides off.  But diamonds have a 3D lattice which have fixed angles and is therefore very hard.  These have high melting points.  

Molecular solids are composed of of molecules with weak intermolecular forces.  These do not conduct electricity, have low boiling and melting points.  These can be made from very large molecules.

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Metallic solids are good conductors.  They are malleable (hammered into shape) and ductile (pulled into wires)

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Large biomolecules or polymers can have interactions between different molecules or between different regions of a large molecule.  These are mainly noncovalent interactions.  

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