Iodine I.

Iodine is essential for our hormonal balance because the iodine-containing hormone thyroxine, which is formed in the thyroid gland, controls many processes in our body. The different oxidation states of iodine are used for analytical applications and iodine compounds are also used in semiconductors for solar cells. To the article about iodine on the Fascination Chemistry page.

One of the best-known experiments with iodine is the oscillating Briggs-Rauscher reaction, also known as the iodine clock, in which an iodine-containing solution changes color over and over again. Nice to see with brisk country music in this video. If you prefer to see it in ultra-slow motion and understand the chemistry there, watch the video from the Periodic Videos series.


The halogens form the 17th group of the periodic table. They include fluorine, chlorine, bromine, iodine and the radioactive astatine.

Tennes, which does not occur naturally, was added a few years ago as element number 117. Tennes was first artificially generated a few years ago at the Dubna Nuclear Research Center near Moscow. Its name refers to the US state of Tennessee, home to another research center, Oak Ridge National Laboratory, where various heavy elements have been synthesized.

back to the periodic table

back to the start page for the year of the periodic table

to our brochure Chemistry of the Elements

published June 2019 with articles on 43 elements (7 MB, 160 pages)

Photo: Jasenka /

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last modified: 10.05.2021 16:39 H from N/A