# Structural Biochemistry/Rare Earth Metals
## The 17 Rare-Earth Elements

* Scandium (Sc)
* Yttrium (Y)
* Lanthanum (La)
* Cerium (Ce)
* Praseodymium (Pr)
* Neodymium (Nd)
* Promethium (Pm)
* Samarium (Sm)
* Europium (Eu)
* Gadolinium (Gd)
* Terbium (Tb)
* Dysprosium (Dy)
* Holmium (Ho)
* Erbium (Er)
* Thulium (Tm)
* Ytterbium (Yb)
* Lutetium (Lu)
Rare earth metals are a group of 15 chemically similar elements known as lanthanides that are grouped separately from the periodic table.
Rare earth metals are generally found in high concentrations in the earth's crust. Humans use these in many advanced technological devices, such as magnets, superconductors, electronic polishers, flints for lighters, refining catalysts, and hybrid car components.
They are also used as active ions in luminescent materials
Rare earth metals or rare earth elements is a set of 17 elements that exhibit similar characteristics. The name of the elements are very misleading because the metals are somewhat easy to find. They are not that rare at all, besides one of them. The only thing rare about these elements is that they are spread thin across the globe. This means that there are no big ore mines of rare earth metals, but instead a fine sprinkling all across the globe. These metals are all heavier than iron which is quite a feat. Rare earth metal prices fluctuate and are sold on a private market making their pricings ambiguous.

## Scandium

Scandium has the atomic number 21. It is a silver-white metal. When exposed to air it can develop a faint yellow or pink color. it is most abundant in the stars. It can react with acids rapidly. Scandium was first discovered by Lars Frederick Nilson in 1876 while he was studying the rare earth metals. It is now used in aluminum-scandium alloys in the aerospace industry as well as sports equipment (i.e. golf irons, bicycle frames). It is also used in mercury vapor lamps.

## Yttrium

Yttrium was first discovered in 1787 by Carl Arrhenius in a mine near Ytterby, Sweden and was first named ytterbite and later to gadolinite, but with further analysis of the metal by multiple scientists it was discovered to be an impure form of the metal. Friedwich Wohler was the first to obtain the Yttrium metal in 1828 by heating anhydrous yttrium(III) chloride with potassium. Yttrium is a soft, silver metal. It usually exists as Y$^{3+}$.
Yttrium is often used in making alloys. And recently has seen great potential in superconductors as well as lasers. Like other rare earth elements is reacts slowly with cold water and quickly with hot. The solid metal does not react with Oxygen in the air, but in its powdered form it can react explosively at higher temperatures. It is fairly common on earth, and is even largely present in rocks that have been brought back from the moon.
Yttrium has been seen to have toxic effects on rats in laboratories, though not much testing has been done on humans. It is often treated with caution.

## Lanthanum

Lanthanum is number 39 in the periodic table. It was first discovered in 1839 by Carl G. Mosander. It can be seen a silver-white metal that is soft enough to be cut by a knife. It most commonly exists as La$^{3+}$. It is ductile and malleable and will easily rust when exposed to air as it will immediately oxidize. It is commonly used in nickel metal hydride rechargeable batteries for hybrid cars. It is also used in making night vision goggles, flame lighter flints, and lenses for high quality cameras and telescopes.

## Cerium

Cerium is number 58 in the periodic table. It is a soft and gray metal. It is also reactive, ductile, and malleable. it can rust when exposed to moist air. It was first discovered in 1803 in Sweden by Jöns J. Berzelius and Wilhelm von Hisinger and in that same year was also discovered by Martin Klaproth in Germany. Cerium is used in carbon-arc lighting. Cerium oxide is used in catalytic converters in cars to reduce CO emissions. Flammacerium is used to treat and prevent infection on extensive burn wounds.

## Praseodymium

Praseodymium is number 59 in the periodic table. it is a silver-white metal. It is soft and malleable and only slightly toxic. It commonly exists as Pr$^{3+}$ and it's salts usually are a pale green color. It was first identified in 1885 by Carl Auer von Welsbach. It is used in the high-intensity permanent magnets necessary for hybrid cars and wind turbines. It is also used when making specialty glass goggles for welders and glass blowers.

## Neodymium

Neodymium is number 60 on the periodic table and has an atomic weight of 144.24 g/mol. It is a silver/white metal that is soft and bright. It has a melting point of 1289K and a boiling point of 3343 K. It existed mostly as Nd$^{3+}$. Its salts usually are a pale purple color. It was first identified by Carl Auer von Welsbach in 1885 when he realized that his earlier discovery of a metal called didymium was actually a mixture of two different elements which were then named neodymium and praseodymium. It is used for NIB magnets used in many electronics and cigarette lighter flints.

## Promethium

Promethium is number 61 on the periodic table. It is the only element of the rare earth metals to be radioactive and is very harmful. It's salt forms luminate a pale blue or green when in the dark.

## Samarium

Samarium is number 62 on the periodic table. It has an atomic weight of 150.4 g/mol. It was first discovered by Jean Charles Galissard de Marignac in 1853 in Geneva, Switzerland when he found lines in the mineral spectra that he had been studying. It is hard and silver metal. In temperatures that are higher that 150$^o$C it will ignite in air, otherwise it is stable in normal temperatures. It usually exists as Sm$^{3+}$ and its salts usually have a pale yellow color. It is used in an alloy magnet that is used in headphones, small motors, and pickups for electric guitars and is also used to as an absorber for nuclear reactors. Radioactive $^{152}$Sm is also used in treating cancer.

## Europium

Europium is number 63 on the periodic table. It's atomic weight is 151.96 g/mol. It is slightly toxic but its metal dust is a fire and explosive hazard. It has a melting point of 1095 K and a boiling point of 1873 K. It is found as a soft and ductile silver/white metal. It immediately oxidized when exposed to air. It is considered the most reactive of the rare earth metals and will ignite in temperature of 150-180$^o$C. It is used in phosphors in anti-forgery marks on Euro bank notes.
The discovery of Europium is accredited to Eugène-Antole Demarçay who, in 1886, had identified spectroscopic lines in Samarium using his own specially developed spectroscope, which was specifically made to study the rare earth metals. Though his results were originally disputed he later proved his findings in 1901 when he was able to isolate europium.

## Gadolinium

Gadolinium is number 64 on the periodic table. Its atomic weight is 157.25 g/mol. It has a melting point of 1587 K and a boiling point of 3533 K. It was first found by Jean Charles Galissard de Marignac in 1880 when he recorded spectroscopic lines in an oxide preparation which had been taken from samarskite. His findings were later confirmed by Paul Émile Lecoq de Boisbaudran in 1886. It is a silver/white metal. It is also ductile and malleable. In moist air it will tarnish. It can usually be found as Gd$^{3+}$.

## Terbium

Terbium is number 65 on the periodic table. It has an atomic weight of 158.9 g/mol. It has a boiling point of 3493 K and a melting point of 1633 K. It is a grayish metal that is malleable and ductile. It is also soft, enough to cut with a knife. It exists as Tb$^{3+}$ and when excited will emit a green luminescence. It was discovered by Carl Gustaf Mosander in 1843 when, hoping to discover yet another element, he used ammonium hydroxide to precipitate fractions of different basicity from yttria. This produced two different substances which he learned contained the new elements erbium and terbium. It is used in color phosphors in trichromatic lighting and TV and also makes the green colors on Blackberry phones.

## Dysprosium

Dysprosium is number 66 on the periodic table. It has a boiling point of 2833 K and a melting point of 1410 K. Its atomic weight is 162.50 g/mol. It is a silver/white metal that is soft and bright. In room temperature it will slowly tarnish. When in acids it will dissolve. It has the highest magnetic strength of all the elements. It usually can be found as Dy$^{3+}$. It was first discovered in 1886 by Paul Émile Lecoq de Boisbaudran when he separated dysprosium oxide from holmium oxide using a time-consuming and intricate procedure. It is used in the cement in control rods in nuclear reactors. It is also used in compact and hard discs.

## Holmium

Holmium is number 67 on the periodic table. It has a atomic weight of 164.9 g/mol. It's boiling point is 2973 K. It has a melting point of 1743 K. It is slightly toxic. It is a malleable, ductile, and soft silver metal. When it is heated or exposed to moist air it will oxidize to a yellowish oxide. It is usually found as Ho$^{3+}$ and it's compounds are usually a brown/yellow color. Like Dysprosium, it has the highest magnetic strength and as such it can be used as a flux concentrator for high magnetic fields. It is also used in lasors used for non-invasive medical procedures in treating cancers and kidney stones. Its isotopes are used to color glass and cubic zirconias red and yellow.

## Erbium

Erbium is number 68 on the periodic table. It has an atomic weight of 167.26 g/mol. It is a moderately toxic silver-white metal. It is also soft and malleable. It tarnishes slowly when exposed to air. It can also r==eact with water and will dissolve in acids. It can most commonly be found as Er$^{3+}$. Erbium salts are usually found to be a pinkish color. It was first discovered by Carl Gustaf Mosander in 1843 by using ammonium hydroxide to precipitate fractions with different basicity of yttria. From there he found 2 different substances with each contained a new element, erbium and terbium. Erbium is used in amplifiers and lasers and photographic filters.

## Thulium

Thulium is number 69 on the periodic table. Its atomic weight is 168.9 g/mol. It is a non-toxic gray metal that is soft and malleable. When exposed in air the metal will slowly tarnish. When reacted with water it will form hydroxide and hydrogen gas. It exists mostly as Tm$^{3+}$. It is one of the least abundant elements. It was first discovered in its oxide form in Uppsala, Sweden in 1879 by Per Teodor Cleve while working with the metal Erbia.

## Ytterbium

Ytterbium is number 70 on the periodic table. It has an atomic weight of 173.04 g/mol. It is a ductile and malleable silvery metal. When exposed to air it will immediately tarnish. It was first discovered by Jean Charles Galissard de Marignac in 1878. He managed to extract an unknown powder, which was named ytterbium oxide, after heating erbium nitrate until decomposition. It is used in alloys used for stainless steel. Its compounds are also commonly used as catalysts in organic chemistry reaction.

## Lutetium

Lutetium is number 71 on the periodic table. Its atomic weight is 174.97 g/mol. It has a boiling point of 3663 K and a melting point of 1933 K. It is a non toxic silver/white metal. It is the hardest and the densest of the lanthanides. $^{177}$Lu is used for cancer therapy and $^{176}$Lu is used to determine the age of meteorites.

## References

* ↑ Rare earth metals, November 14th, 2012.
<a href="http://www.chemicool.com/">Chemicool Periodic Table</a>
"Yttrium." Chemistry Explained. Advameg, Inc. 2012. http://www.chemistryexplained.com/elements/T-Z/Yttrium.html#b