The Chemical Elements: Iodine

Hello - and welcome to this week's Chemical Elements post - featuring the PURPLE element!

If you are confused by any of these terms, go to the glossary!

Facts about iodine

Symbol: I
Electron configuration: [Kr] 4d¹⁰5s²5p⁴
Atomic number: 53
Key isotopes: ¹²⁷I

Relative atomic mass: 126.904
Melting point: 113.7 °C
Boiling point: 184.4 °C
Electronegativity: 2.66
1^st ionisation energy: 1008.393 kJ mol^-1

Iodine has many commercial uses. Iodide salts are used in pharmaceuticals and disinfectants, printing inks and dyes, catalysts, animal feed supplements and photographic chemicals. Iodine is also used to make polarising filters for LCD displays.

Iodide is added in small amounts to table salt, in order to avoid iodine deficiency affecting the thyroid gland. The radioactive isotope iodine-131 is sometimes used to treat cancerous thyroid glands. Iodine is an essential element for humans, who need a daily intake of about 0.1 milligrams of iodide. Our bodies contain up to 20 milligrams, mainly in the thyroid gland. This gland helps to regulate growth and body temperature. Normally we get enough iodine from the food we eat. A deficiency of iodine can cause the thyroid gland to swell up (known as goitre).

Iodine is found in seawater, as iodide. It is only present in trace amounts (0.05 parts per million); however, it is assimilated by seaweeds. In the past iodine was obtained from seaweed. Now the main sources of iodine are iodate minerals, natural brine deposits left by the evaporation of ancient seas and brackish (briny) waters from oil and salt wells.

…Okay. I did copy and paste here. But I wanted to post something today, considering that I haven't for the past two weeks. Here's the web page with the information.

Anyway, that's all from me for today. I'll see you next week for another blog post - so bye for now!