Question

Under which category, iodine crystals are placed among the following?
A. Ionic crystal
B. Metallic crystal
C. Molecular crystal
D. Covalent crystal

Answer 1

Hint: A regular configuration of the constituent particles in a three-dimensional space is called a crystal lattice or space lattice. The constituent particles may be atoms, molecules or ions. The constituent particles in a molecular solid are the molecules.

Complete Step by Step Solution:
- Crystalline solids are a type of solid in which the constituent particles are arranged in a definite organised manner.
- Crystalline solids are of four types.
- One of them is molecular solids.
- Molecular solids are again divided into three types.
- Non-polar molecular solids are one of them.
- Crystalline solids in which constituent particles are either atoms like those of noble gases or nonpolar molecules like hydrogen, chlorine, methane, etc.
- We know that iodine is a nonpolar molecule.
- Weak dispersion or London forces act on these types of solids.
So, iodine crystal is a type of non-polar molecular crystal.
So, option C is correct.

Additional Information: These nonpolar molecular solids are soft due to weak intermolecular forces present between iodine molecules. There are no ions present in them so they are non-conductors of electricity. They are usually gases or liquids at room temperature due to weak molecular force of attraction.

Note: Molecular solids are divided into three categories which are non-polar molecular solids, polar molecular solids and H-bonded molecular solids.
Polar molecular solids contain polar molecules like hydrochloric acid, sulfur dioxide etc. The intermolecular force of attraction present is dipole-dipole interaction.
Hydrogen-bonded molecular solids contain molecules containing the hydrogen atom linked to highly electronegative atoms like F, O or N. The intermolecular force of attraction present is hydrogen bonding.