I
126.900Iodine
İyot
Iodine is a solid halogen with atomic number 53. It is essential for thyroid hormones, appears as dark crystals that give violet vapor, and is important in iodized salt, antiseptics, medical radioisotopes and the iodine-starch test.
53
126.9 g/mol
[Kr] 4d¹⁰ 5s² 5p⁵
2 | 8 | 18 | 18 | 7
2.66
4.933 g/cm³
113.7 °C
184.3 °C
Bernard Courtois
Iodine was discovered in 1811 by Bernard Courtois while processing seaweed ash. Its name comes from the Greek ioeides, meaning violet-colored, because iodine vapor is violet.
Iodine-127
Natural abundance: 100%. The only stable natural iodine isotope.Iodine-123
Half-life: About 13.2 hours. Gamma-emitting isotope used in thyroid imaging.Iodine-131
Half-life: About 8.0 days. Beta and gamma emitter used in thyroid therapy and important in nuclear fallout.KI
Potassium IodideIodized salt additive, Lugol solution component and thyroid-blocking tablets in nuclear emergencies.I₂
Molecular IodineAntiseptic, analytical reagent and iodination chemistry.NaIO₃
Sodium IodateSalt iodization and oxidizing agent.AgI
Silver IodideCloud seeding and photographic chemistry.- Iodized salt for preventing iodine deficiency disorders
- Povidone-iodine antiseptics for skin disinfection and wound care
- Iodine-131 therapy for thyroid cancer and hyperthyroidism
- Iodine-123 imaging for thyroid scans
- Silver iodide for cloud seeding
- Iodine-containing polarizing films in LCD displays
Iodine is an essential trace element. Thyroid hormones T₃ and T₄ contain iodine and regulate metabolism, growth and nervous-system development; deficiency can cause goiter and developmental problems.
- Iodine sublimes to a violet vapor when gently heated.
- Iodized salt is one of the most successful public-health interventions for preventing iodine deficiency.
- The iodine-starch test gives a dark blue-black color because polyiodide species fit inside starch helices.
- Potassium iodide tablets protect the thyroid by saturating it with stable iodine during certain nuclear incidents.
- Iodine has atomic number 53 and belongs to group 17, the halogens.
- Its electron configuration is [Kr] 4d¹⁰ 5s² 5p⁵.
- Iodine is a solid halogen at room temperature and forms violet vapor.
- Connect iodine with thyroid hormones, iodized salt, I-131 and the starch test.
What is the atomic number of iodine?
The atomic number of iodine is 53.
What is the electron configuration of iodine?
Iodine has the electron configuration [Kr] 4d¹⁰ 5s² 5p⁵.
Why does the body need iodine?
The body needs iodine to make thyroid hormones T₃ and T₄, which regulate metabolism and development.
What is iodine used for?
Iodine is used in iodized salt, antiseptics, thyroid medicine, medical imaging, cloud seeding and chemical analysis.
What is iodine-131 used for?
Iodine-131 is used to treat some thyroid diseases and is also a notable radioactive isotope in nuclear fallout.
What color is iodine vapor?
Iodine vapor is violet or purple, which is the origin of the element’s name.