The Four Main Structure Types

Giant Ionic lattice

(NaCl, MgO)

Has strong electrostatic attractions

Usually high melting/boiling points

Does not conduct when solid because ions are fixed

Conducts when molten or dissolved if ions are mobile

Giant metallic lattice

(Magnesium, copper)

Positive ions and delocalised electrons

Conducts in solid and liquid stats

Often malleable because layers can slide while metallic attraction is maintained

Giant covalent (macromolecular)

(Diamond, graphite)

Atoms joined by covalent bonds throuughout a gaint network

Usually high melting points

Conductivity depends on structure : graphite conducts; diamond does not

Simple molecular

(I*2, H*2O(ice))

Strong covalent bonds within molecules

Intermolecular forces between molecules

Often lower melting/boiling points than giant structures

Usually do not conduct