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Understanding the element
Iodine (I) is chemical element 53. It belongs to the halogens, and its reference state at room temperature is a solid. Those basic facts are a useful starting point for its chemistry and applications.
Where do we encounter it?
In practice, it turns up most often in thyroid function and nutrition, antiseptics and photography.
thyroid function and nutritionantisepticsphotography
Standard atomic weight126.90447(3)
What its position in the table tells us
Iodine sits in period 5, group 17 and the P block. That location is useful because neighbouring elements often share trends in valence electrons, oxidation states and bonding behaviour.
Worth remembering
Iodine has a characteristic place in the periodic table that helps explain both its chemistry and its practical uses
Iodine has a characteristic place in the periodic table that helps explain both its chemistry and its practical uses