Sci Tidbits: Science for everyday life: Iodine - Element of the Week from 11/9-11/16

Friday, November 16, 2012

Iodine - Element of the Week from 11/9-11/16

Iodine is element 53 and is a bluish-black solid. Its name is derived from the Greek word "iodes" which means violet. This name makes sense because iodine produces a foul-smelling purple smoke when dissolved in various solutions. It is only minimally soluble in water.

Bernard Courtois, a French chemist, discovered it in 1811. After doing some initial research (and seeing the telltale purple vapor), Courtois believed that he had discovered a new element, but did not have the funding required to determine if he was right. It was in November of 1813 that fellow chemists, Nicolas Clement and Charles Bernard Desormes made his discovery public.

Iodine is rare in space and on Earth. It exists in higher concentrations in seawater than in rocks. Iodine is esential for human life to exist, and is the second heaviest element to fit into this category - Tungsten being the heaviest. There is one stable isotope of the 37 known for iodine.

There are many uses for Iodine. One of which is treating an area of skin before putting a needle in for giving blood (I experienced it yesterday!) The major application is as the co-catalyst for the production of acetic acid. It is also widely used as a disinfectant - as stated above. Iodine is also used as a radiocontrast agent in X-raying.

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In honor of one of my best friends (see above), the first element I have chosen to highlight after my long absence is... Lutetium.

Lutetium is element number 71, and the smallest of the lanthanide series. It was the last natural rare earth metal to be discovered, and is monoisotopic.

This element has a long and convoluted history, so here is a sequential list of events.

1. Gadolinite, a mineral, was discovered in a quarry near Ytterby, Sweden

2. Carl Gustaf Mosander, a Swedish chemist, separates gadolinite into three different materials - yttria, erbia, and terbia

3. By 1878, erbia and terbia switched names

4. In the same year, a Swiss chemist, Jean Charles Galissard de Marignac discovered that erbia was actually two compounds - one still named erbia and the other named ytterbia (believed to be a new element - ytterbium)

5. Scientists had problems determining the properties of ytterbium, so...

6. In 1907, a French chemist, Georges Urbain, and a German chemist, Baron Carl Auer von Welsbach, both were able to separate ytterbium into two elements

7. There were two sets of names: neoytterbium and lutecium (Urbain) and albebaranium and cassiopium (Welsbach)

8. Urbain got the credit for the discoveries, and the names changed to became ytterbium and lutetium

Whew. Another chemist, this time of British origin, named Charles James, isolated lutetium around the same time as Urbain and Welbash, and also patented a method of isolating rare earth metals, bromate fractional crystallization, that was widely used until the 1940s.

Not surprisingly, lutetium is one of the most difficult elements to prepare, as it is extremely difficult to separate from other rare earth elements. All of these factors result in a very rare and expensive pure metal, and thus there are few commercial uses for lutetium. One use of lutetium is in petroleum cracking in refineries (the process of breaking long hydrocarbons chains into small ones). The radioactive isotope, Lutetium-176, has been used in lutetium-hafnium dating of meteorites.

Good overview of element - here