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General Info
Atomic Symbol Atomic symbol::Sm
Atomic Number Atomic number::62
Atomic Weight Atomic weight::150.4 g/mol
Chemical series Lanthanides
Appearance silvery-white
Samarium sample.jpg
Group, Period, Block n/a, 6, f
Electron configuration [Xe] 6s2, 4f6
Electrons per shell 2, 8, 18, 24, 8, 2
Electron shell samarium.png
CAS number CAS number::7440-19-9
Physical properties
Phase solid
Density Density::7.54 g/ml
Melting point Melting point::1074 °C
Boiling point Boiling point::1794 °C
Isotopes of Samarium
iso NA half-life DT DE (MeV) DP
144Sm 3.07% 144Sm is stable with 82 neutrons.
146Sm syn 1.03x108 y α 2.529 142Nd
147Sm 14.99% 1.06x1011 y α 2.310 143Nd
148Sm 11.24% 7x1015 y α 1.986 144Nd
149Sm 13.82% >2x1015 y α 1.870 145Nd
150Sm 7.38% 150Sm is stable with 88 neutrons.
152Sm 26.75% 152Sm is stable with 90 neutrons.
154Sm 22.75% 154Sm is stable with 92 neutrons.
All properties are for STP unless otherwise stated.

Samarium is a chemical element in the Lanthanide series with an atomic number of sixty-two. It is well known for its use in samarium cobalt magnets, the second most powerful magnet in the world. Samarium was named after a Russian mining official, Colonel Samarski. This was the first naturally occurring chemical element named after a person, thus starting a new trend in the naming of elements. It is a rare earth metal that is not found in its pure form in nature; it must be extracted from a compound. There are many different ways to extract samarium, the most effect of which is electrochemical deposition.[1]


In addition to the properties listed in the table to the right, [2] [3] Samarium is extremely electropositive this means it is able to lose electrons in a chemical reaction. When exposed to cold water, it will react slowly. However when exposed to hot water, it does the opposite reacting quickly and creating samarium hydroxide or hydrogen gas. Samarium metal, if left out in open air will tarnish, but not right away. It also is able to burn and create samarium (III) oxide. Samarium metal will bond with all halogens, creating samarium (III) halides. [4]


Mining for Monazite

Samarium is often found in nature; in fact it is the fifth most common of all the rare elements, but never in its pure form. [5] Samarium can be found in samarskite, monazite, and bastnasite; both monazite and bastnasite are commercial sources of Samarium. Samarium can not be found in a pure form in nature, and until recently samarium was not isolated into its pure form. Some ways in which Samarium is isolated include; ion-exchange (a reversible chemical reaction were ions are replaced, in a insoluble material, by ions in adjacent solutions [6]), solvent extraction, electrochemical deposition (using a mixture of lithium citrate and a mercury electrode, to produce an electrolytic solution) and Samarium metal can be made by the reduction of oxide with the lanthanum. [7]


Five Samarium Cobalt magnets
Samarium has many uses as a catalyst in organic reactions. The catalyst form of Samarium can be used to dehydrate ethanol or in the dehydrogenation of ethanol. Also, the oxide form of Samarium can make infrared adsorbing glass and is used in the core of arc-lamp electrodes.[5] An arc lamp is a lamp that uses the fact that electricity will jump from one electrode to another, to create light. [8] Samarium can be used in lasers to change conductivity, in nuclear reactors, metal alloys, and even an occasional ceramic.

A surprising use for Samarium is in the field of medicine since Samarium can be toxic.[9] A radioactive isotope of Samarium is used in the making of "samarium SM 153 lexidronam", a radiopharmaceutical used to relieve bone pain received through certain forms of cancer. It works by emitting radiation after being taken to the bone cancer area, this treatment then provides relief from pain. It can either be injected or taken in the form of a solution. No studies have been done to determine whether it is a safe treatment for children. Older people seem to not be reacting to the drug in any abnormal way, when compared with young adult’s reaction to the drug. However this drug may lower the number of white blood cells or platelets that a person produces. This is a dangerous situation because it means that someone’s may not be able to fight an infection as quickly and effectively, because of their lack of white blood cells. Also a lower amount of platelets a person has means they may be unable to form blood clots. [10]

The second most powerful magnetic material is made out of Samarium. Samarium Cobalt is extremely expensive to manufacture, so it is usually only used in the field of aerospace, were the effectiveness of the material is more important then the cost. Samarium Cobalt magnetic material is extremely resistant to demagnetization, and corrosion. As well as maintaining its effectiveness to a temperature of 350°C. [11]


A piece of Samarskite with a pen for scale

Samarium has a long and complicated history; it started with the discovery of ytterbite (ytterbium), in 1787 by Lieutenant Carl Axel Arrhenius, which was later renamed gadolinite (gadolinium). A professor from the University of Turku, named Anders Gustav Ekeberg, discovered beryllium in gadolinite, in 1794. However, he missed the ore ceria (cerium) discovered in 1803, by Jöns Jacob Berzelius and Wilhelm Hisinger. From this, Carl Gustav Mosander isolated both lanthana (lanthanum) and didymia with a gap of 3 years between each discovery. [12] Mosander believed he had discovered two new elements. This was an accepted fact up until 1880; this was when a French chemist named Paul-Emile Lecoq de Boisbaudran began studying didymium and stated that there were at the least two more elements inside this so called element. Simultaneously, another French chemist named Jean-Charles-Galissard de Marignac also was in the process of studying didymium; he had the same success as Boisbaudran in separating didymium into two different parts. Marignac named these two parts didymium and samarium, calling samarium a new element. These two “elements” were accepted for twenty years until yet another French chemist named Eugene-Anatole Demarcay began studying them. Demarcay was able to split Margnac’s samarium into two more parts; he named these new elements samarium and europium. Because of all the different beliefs in regards to what was a true element, credit for discovering Samarium is sometimes given to Boisbaudran, Marignac, and Demarcay or just one of the three.

The name samarium comes from samarskite, a mineral that samarium is often found in. The mineral was named after Colonel Samarski, a Russian mine official. [13]


  1. Chemistry in Its Element - Samarium Unknown Author, Royal Society of Chemistry, Accessed: December 2, 2010
  2. Samarium Element Facts Unknown Author, Chemicool, Accessed: November 18, 2010
  3. Samarium Oxide Unknown Author, American Elements, Accessed: November 18, 2010
  4. Samarium Dr Mark J Winter, The University of Sheffield and WebElements Ltd, UK, Accessed: November 27, 2010
  5. 5.0 5.1 Samarium - Sm Unknown Author, Lenntech, Accessed: November 22, 2010
  7. Samarium Unknown Author, University of California, Last Updated: 12/15/2003.
  8. Arc Lamp WordNet, WordNet Search, Accessed: November 22, 2010
  9. What is Samarium? Written by S.E. Smith, wiseGEEK, Last Modified: 10 September 2010
  10. samarium sm 153 lexidronam (Intravenous route) Unknown Author,, Accessed: December 2, 2010
  11. Magnet Materials Unknown Author, Dura Magnetics, Inc, Accessed: November 27, 2010
  12. Rare Earth Element | Discovery And Early History Unknown Author, Rare Metal Mining Directory, September 24, 2010
  13. Samarium an imprint of Thomson Gale, a division of Thomson Learning, Inc., Accessed: November 27, 2010