A physical property that connects all giant covalent structures is that their three-dimensional structure repeats interminably, and the number of connected atoms entirely depends on the size of the structure. Giant covalent structures are also bound very tightly and require much more energy than other molecular structures to break.
So much energy is needed to break the bonds because each atom is held in place by another atom in a three-dimensional arrangement. This makes giant covalent structures relatively insoluble in liquids, and they possess low electrical conductivities due to the lack of free ions. The five giant covalent structures are diamond, silicon carbide, silicon dioxide, silicon and graphite.