Final answer:
Iodine undergoes sublimation when heated gently due to strong dispersion forces, and it is a poor conductor of electricity because it lacks free-moving charges or delocalized electrons.
Step-by-step explanation:
Iodine vaporizes when heated gently due to a process called sublimation, where a solid turns directly into a gas without first becoming a liquid. This happens because iodine has relatively strong dispersion forces among its molecules, which are overcome by the heat, allowing it to enter the gaseous phase directly from the solid phase. When iodine vapors come in contact with a cold surface, they deposit as solid iodine again, which can be seen as the formation of I2 crystals.
Iodine is a very poor conductor of electricity because it is a molecular solid with molecules held together by dispersion forces. These forces do not create free charges or delocalized electrons required to conduct electricity. Thus, iodine lacks the ability to conduct an electric current, unlike metallic or ionic compounds, that have free-moving charges or ions.
Examples of good thermal conductors and insulators:
Good thermal conductors: Metals such as silver and copper
Good insulators: Materials such as rubber and wood