There are five main types of crystalline solids: metallic, ionic, network covalent, molecular nonpolar, and molecular polar. Each type is characterized by the structural particles it contains, the intermolecular forces between those particles, and typical physical properties like hardness, melting point, conductivity, and solubility. Metallic solids contain cations and delocalized electrons bonded by metallic bonds, resulting in properties like conductivity and ductility. Ionic solids contain cations and anions bonded by electrostatic attractions, making them brittle with high melting points. Network covalent solids form covalent bonds between atoms, giving properties like high hardness and melting points.