12.1 classification and structures of solids

metallic solids

metal atoms held together by localized “sea” of collectively shared valence electrons. Strong, not brittle, good at conducting electricity.

ionic solids

anions and cations held together by mutual electrostatic attraction. Brittle and bad at conducting electricity.

covalent-network solids

solids held together by extended network of covalent bonds. Can result in very hard materials and responsible for properties of semi-conductors.

molecular solids

discrete molecules held together by intermolecular forces. Weak, soft, and have a low melting point.

polymers

Solids with large chains of atoms (usually carbon). Atoms are held together with covalent bonds and chains are held together with weaker intermolecular forces.

nanomaterials

solids where the dimensions of individual solids have been reduced to the order of 1-100 nm.

crystalline solid

solids where atoms are arranged in an orderly repeating pattern.

amorphous solid

solids whose molecular arrangement lacks the order of a crystal.