Iodine ingested iodine and retain it for periods longer than this isotope's radiological half-life of eight days. For this reason, people at risk of exposure to environmental radioactive iodine (iodine-131) in fallout may be instructed to take non-radioactive potassium iodide tablets. The typical adult dose is one 130 mg tablet per 24 hours, supplying 100 mg (100,000 micrograms) of ionic iodine. (The typical daily dose of iodine for normal health is of order 100 micrograms; see "Dietary Intake" below.) Ingestion of this large dose of non-radioactive iodine minimises the uptake of radioactive iodine by the thyroid gland. As an element with
Iodine heptafluoride Iodine heptafluoride Iodine heptafluoride, also known as iodine(VII) fluoride or iodine fluoride, is an interhalogen compound with the chemical formula IF. It has an unusual pentagonal bipyramidal structure, as predicted by VSEPR theory. The molecule can undergo a pseudorotational rearrangement called the Bartell mechanism, which is like the Berry mechanism but for a heptacoordinated system. It forms colourless crystals, which melt at 4.5 °C: the liquid range is extremely narrow, with the boiling point at 4.77 °C. The dense vapor has a mouldy, acrid odour. The molecule has D symmetry. IF is prepared by passing F through liquid IF at