Iodine

Iodine is a chemical element, having the chemical symbol I.

Iodine 126.90447(3)   I 53 [Kr] 4d10 5s2 5p5 [ ? ] Halogen:

Its atomic number (the number of protons) is 53. It has a Standard Atomic Weight of 126.90447(3), and is typically found as a solid in its elemental form.

Iodine is considered to be a member of the "Halogen" class of elements, has a boiling point of 184.4 °C , and a melting point of 113.7 °C .

Iodine 126.90447(3) +3 +5 0 -3   I 53 [ ? ] Halogen: Properties: halogen Compounds: halides

Xenon is a chemical element with atomic number XX that consists of a mixture of nine stable isotopes. Twenty additional unstable isotopes have been identified.

Chemical applications

Iodine is specified as a List I chemical by the US Drug Enforcement Administration and is considered to have high risk of diversion to illicit drug manufacturing.

Sublimed iodine has been used as a general reagent for developing invisible ink, as it recrystallizes on paper fibers disturbed by the act of writing. For this purpose, however, it has largely been displaced by specialized photographic methods.

Radioactive iodine

Several isotopes of iodine, including ¹²³I, ¹²⁴I, ¹²⁹I and ¹³¹I are radioactive isotopes of iodine used to treat certain cancers or for medical imaging processes and ¹³¹

Both ¹²⁹I and ¹³¹I has been produced from:

1. Nuclear weapons production and atmospheric testing
2. Deliberate production for medical use, involving the irradiation of tellurium
3. Nuclear fission in nuclear energy facilities, and released through accidents such as Three Mile Island.

For reasons of national security, the knowledge of contamination was suppressed in the United States.

The release of iodine-131 in a serious power reactor accident could be retarded by absorption on metal surfaces within the nuclear plant.

• Glänneskog H (2005) Iodine chemistry under severe accident conditions in a nuclear power reactor, PhD thesis, Chalmers University of Technology, Sweden
• For other work on the iodine chemistry which would occur during a bad accident, see[1][2][3]</ref>

Decay and decay products

¹³¹I has a half-life of only 8.06 days, so environmental spills are of much less concern that similar spills of other radioactive elements such as cesium or uranium.

However, ¹²⁹I has a half-life of 15.7 million years. Thus, a spill of ¹³¹I one thousand times the normal background would decay back to normal levels in about 81 days. The ¹²⁹I and ¹³¹I atoms emit beta particles and emit gamma radiation during radioactive decay. Because iodine is readily absorbed by the thryroid gland, which uses it to produce thyroid hormones, ingestion of radioactive iodine can lead to thyroid pathology, including thyroid cancer.

Ingestion

Like bromine, iodine is readily sublimed, going from the solid state directly to the gaseous state,(skipping the liquid state) so exposure to the solid form can still lead to inhalation of the chemical. Being a halogen, it also readily forms many salts which are readily soluble, so the molecular form is quickly converted into various salts upon reaction with most environments. Dairy animals exposed to any form of radioactive iodine can thus lead to ingestion by humans.