Intro/History:

Iodine was discovered by Bernard Courtois in 1811 in a chemical accident when he was separating saltpeter from algae using sulfuric acid. He accidentally put too much acid resulting in a big cloud of un-breathable purple gas. The gas then condensed on cold metallic surfaces forming little crumbly dark-purple rocks. Since he didn’t have the money to continue his research, he asked two scientist friends to do so. Both of them came up with the same results and had an argument about who had found it first. They finally settled on one decision; Courtois had discovered the new element.

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Properties:

Iodine is a lustrous crumbly dark-purple solid that is solid at room temperature. Its melting point is 236.66 degrees Fahrenheit and its boiling point is 363.7 degrees Fahrenheit. Iodine has a density of 4.933 g/cm^3 and its atomic mass is126.904 g/mol. Iodine belongs to the chemical series of Halogens. On the periodic table, it is placed between Tellurium and Xenon on the far left side. The iodine molecule has five electron shells. Each shell has a certain number of electrons, starting with the center, 2, 8, 18, 18, and 7. The iodine molecule has 53 protons and 73 neutrons. Iodine dissolves easily in chloroform to form a purple solution. Iodine is the least reactive but the most electropositive of the halogens and is nonmagnetic.Iodine's molecular formula is RMM=127. When iodine is mixed with water, it results in a pale yellow color.

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Uses:

Iodine can be used in many useful and helpful ways: Tincture of iodine is part of any emergency survival kit and used both for disinfecting wounds and to sanitize surface water for drinking. Some compounds of iodine are useful too such as silver iodide used mainly in photography and potassium iodide can be given to people in a nuclear disaster area to flush out radioactive materials in the body.In places where there is little iodine in the diet—usually where no seafood is eaten—lack of iodine causes the thyroid gland to goiter(see pictures). In some areas, this is now solved by adding small amounts of iodine to table salt in form of sodium iodide or potassium iodide, forming iodized salt.

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Where is it found?:

Iodine can be found in seaweed and kelp (see picture) meaning that there are large quantities of it in underwater coral reefs where algae grow. It can also be obtained through the reaction of potassium iodide with copper sulfate resulting in an ultra pure form of iodine.

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Bibliography:

1: www.wikipedia.org, search iodine (link)
2: www.google.com, search iodine (link)
3: Encarta, search iodine (link)
4: Encarta, table of periodic elements (link)
5: Heiserman L., David. Exploring Chemical Elements and their Compounds, Blue ridge Summit:McGraw-Hill, Inc,1940

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