Sci Tidbits: Science for everyday life: Krypton - Element of the Week from 9/28-10/5

Friday, October 5, 2012

Krypton - Element of the Week from 9/28-10/5

Krypton was discovered in 1898, by the Scottish Chemist Sir William Ramsey, and English chemist Morris Travers. It was not intentionally discovered, but instead was a result of testing to find Argon. The process included removing oxygen and nitrogen from liquid air, and it was during this time that a bright yellow and green line were found in the resulting spectrum. The name Krypton is derived from the Greek word "kryptos", which means hidden. This comes from the way in which it was discovered.

Krypton exists naturally as a gas, in a concentration of 1 ppm in the atmosphere. Solidified Krypton is white and crystalline in appearance. There are six natural, stable isotopes and 30 unstable isotopes and isomers. One isotope, ⁸⁵Kr, is an inert radioactive gas, with a half-life of over 10 years. It is produced by the fission of uranium and plutonium - think nuclear bombs and reactors.

Some uses of Krypton gas include in photography, as the gas emits a brilliant white light. Krypton and Argon gases are mixed and are the fill gas in many energy-saving fluorescent lamps. ⁸³Kr is used with MRI imaging of airways.

Interestingly, Radon was the only noble gas that William Ramsey was not responsible for discovering, and he and Morris discovered three new elements [Krypton, Neon, and Argon] in a period of only 42 days!

A fun picture of Sir William Ramsey - here!

Read more - here!

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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