Metallic Solids

Metallic bonding, studied already in Class XI, gives metallic solids their own distinct structure: the lattice points are occupied by positive metal ions, while a 'cloud' or 'sea' of delocalised (mobile) electrons pervades the entire space between them, belonging to the crystal as a whole rather than to any one ion.

This electron-sea picture explains every one of metallic solids' hallmark properties: they are hard and have high melting points (the metal cations are held firmly in the electron sea), they possess excellent electrical and thermal conductivity (the delocalised electrons are free to move and carry both charge and heat), and they possess a bright metallic lustre (the free electrons readily absorb and re-emit lig …