Question

Which of the following are polar molecular solids?
Solid sulfur dioxide, Solid ammonia, Iodine crystals, Graphite, and Carbon tetrachloride

Answer 1

Hint: We must know that the polarity is the property which is shown by covalently bonded molecules. We can determine the polarity of a covalently bonded molecule by using numerical means, find the difference between the electronegativity of the atoms; if the result is between 0.4 and 1.7, then, generally, the bond is polar covalent.
On the basis of polarity or net dipole moment, molecular solids are classified as polar and nonpolar molecular solids.

Complete step by step answer:
Solid sulfur dioxide is a polar molecular solid because the net dipole moment is non zero and constituent particles are molecules. The electronegativity of sulfur is 2.5 and that of oxygen is 3.5. Therefore, the sulfur-oxygen bonds are polar.
Solid ammonia is a hydrogen-bonded molecular solid because constituent particles are molecules and bonded by hydrogen bonds. In solid \[N{H_3}\],the electronegativity for nitrogen is 3.0, while the electronegativity for hydrogen is 2.1. Therefore, the difference within the electronegativity is 0.9. Hence, solid ammonia is polar.
Iodine crystals are nonpolar molecular solid because constituent particles are molecules and the net dipole moment is zero. The electronegativity values of Carbon and Iodine; for both, it is 2.5.
Graphite is a covalent or network solid because constituent particles are atoms and bonded by covalent bonds.
Carbon tetrachloride is a nonpolar molecular solid because constituent particles are molecules and the net dipole moment is zero.

Note:
We must know that all crystalline solids are having a definite arrangement of constituent particles. Crystalline solids have definite geometry and sharp melting point and it is anisotropic in nature and has physical properties similar in all directions.
Crystalline solids have close-packed structures of constituent particles. Constituent particles are molecules for molecular solids, atoms for covalent solids, ions for ionic solids and metal atoms or kernel, and mobile electrons for metallic solids.
Fusion enthalpy of crystalline solids has a fix or definite value.
Four types of crystalline solids are
1. Molecular solids
2. Ionic solids
3. Metallic solids
4. Covalent or network solids.