 Dominated by... ◦ Closely packed particles ◦ Relatively fixed position ◦ Highest intramolecular attractions  Are... ◦ Definite shape and volume ◦ Definite melting point ◦ High density ◦ Incompressible ◦ Low rate of diffusion

Can be crystallineCan be amorphous Insulin crystalsObsidian

Have a regular repeating pattern of particles

 Ionic crystals ◦ Made of ions – hard and brittle ◦ Ex. NaCl  Metallic crystals ◦ Made of metals with free moving electrons  Covalent crystals ◦ Made of molecules ◦ Ex. Quartz (SiO 2 ), water, sugar  Atomic Crystals ◦ Made of atoms of one element ◦ Ex. Diamond or graphite

 No regular pattern in the particles, without a particular shape  Ex. Glass, plastics, wax, cotton candy