Silicon Dioxide Covalent Crystal Structure Model Kit

Each silicon atom can bond to 4 oxygen atoms, and this gives rise to a giant covalent network structure which each Si is bonded to four oxygens and each 0 to two silicon atoms. Again, the bonding between the atoms goes on and on in three dimensions.
Silicon dioxide is insoluble in water and has a very high melting point (171 0 oc) due to its strong covalent bonds which must be broken in order to melt or dissolve. It is the component of quartz and sand used in the glass industry.