Final answer:
Iodine occurs as a solid at room temperature and undergoes sublimation when heated, changing directly from a solid to a gas. When the heated iodine vapor comes in contact with a cold surface, it deposits back into solid iodine crystals.
Step-by-step explanation:
Iodine occurs as a solid at room temperature. When it is heated, iodine undergoes sublimation, which means it directly changes from a solid to a gas without becoming a liquid. This process can be observed by heating solid iodine, causing it to turn into purple vapor. When the iodine vapor comes in contact with a cold surface, it deposits back into solid iodine crystals.