Why is iodine a solid that can turn into vapor so easily?
Quick Answer
Iodine sublimes because its molecules are held together by relatively weak intermolecular forces. When warmed, it can go directly from solid to gas without becoming liquid first.
The Full Story
Iodine is a nonmetal that forms dark crystalline solids at room temperature, but it has a strong tendency to sublime. That means its molecules can escape directly into the gas phase because the attraction between them is relatively weak compared with many other solids. When iodine vapor forms, it appears as a striking purple gas, which has long made it useful in demonstrations and analysis. This behavior is common in some substances with high vapor pressure, especially under gentle heating.
Key Facts
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