Which of the following substances is a network solid?
a) CH4 (s)
b) CsF (s)
c) H2O (s)
d) SiO2 (s)
d) SiO2 is a network solid.
Explanation a) Solid methane is molecular solid, it has more specificaly a simple molecular structure when it is a solid (about-180 deg C). b) Cesium chloride is an ionic solid. c) Ice is a molecular solid, as the water molecules are held together NOT by covalent or ionic bonds, but by intermolecular forces. d) Silicon dioxide is a network solid. Types of Solids:
Molecular solid (molecular solids are composed of molecules held together by relatively weak forces. Thus, these solids tend to be soft, easily melted, and more or less volatile. Molecular solids are likely to be insoluble in water but soluble in organic solvents).
Ionic solid (a solid that consist of cations and anions held together by the electrical attraction of opposite charges (ionic bonds)).
Covalent network solid (a solid that consists of atoms held together in large networks or chains by covalent bonds). In network solids, conventional chemical bonds hold the chemical subunits together. The bonding between chemical subunits, however, is identical to that within the subunits, resulting in a continuous network of chemical bonds. Two common examples of network solids are diamond (a form of pure carbon) and quartz (silicon dioxide). In quartz one cannot detect discrete SiO2 molecules. Instead the solid is an extended three-dimensional network of ...-Si-O-Si-O-... bonding.