Cerium () is a chemical element with the symbol Ce and atomic number 58. It is a soft, silvery, ductile metal which easily oxidizes in air. Cerium was named after the dwarf planet (itself named for the Roman goddess of agriculture). Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight. It is found in a number of minerals, the most important being monazite and bastnasite. Commercial applications of cerium are numerous. They include catalysts, additives to fuel to reduce emissions and to glass and enamels to change their color. Cerium oxide is an important component of glass polishing powders and phosphors used in screens and fluorescent lamps.

Characteristics

Physical properties

Cerium is a silvery metal, belonging to the lanthanide group. It resembles iron in color and luster, but is soft, and both malleable and ductile. Cerium has the second-longest liquid range of any element: 2648 C° (795 °C to 3443 °C) or 4766 F° (1463 °F to 6229 °F). (Thorium has the longest liquid range.)

Cerium is especially interesting because of its variable electronic structure. The energy of the inner 4f level is nearly the same as that of the outer or valence electrons, and only small energy is required to change the relative occupancy of these electronic levels. This gives rise to dual valency states. For example, a volume change of about 10% occurs when cerium is subjected to high pressures or low temperatures. It appears that the valence changes from about 3 to 4 when it is cooled or compressed. The low temperature behavior of cerium is complex. Four allotropic modifications are thought to exist: cerium at room temperature and at atmospheric pressure is known as γ cerium. Upon cooling to –16 °C, γ cerium changes to β cerium. The remaining γ cerium starts to change to α cerium when cooled to –172 °C, and the transformation is complete at –269 °C. α Cerium has a density of 8.16; δ cerium exists above 726 °C. At atmospheric pressure, liquid cerium is more dense than its solid form at the melting point.

Chemical properties

Cerium metal tarnishes slowly in air and burns readily at 150 °C to form cerium(IV) oxide: :Ce + O₂ → CeO₂

Cerium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form cerium hydroxide: :2 Ce (s) + 6 H₂O (l) → 2 Ce(OH)₃ (aq) + 3 H₂ (g)

Cerium metal reacts with all the halogens: :2 Ce (s) + 3 F₂ (g) → 2 CeF₃ (s) [white] :2 Ce (s) + 3 Cl₂ (g) → 2 CeCl₃ (s) [white] :2 Ce (s) + 3 Br₂ (g) → 2 CeBr₃ (s) [white] :2 Ce (s) + 3 I₂ (g) → 2 CeI₃ (s) [yellow]

Cerium dissolves readily in dilute sulfuric acid to form solutions containing the colorless Ce(III) ions, which exist as a [Ce(OH₂)₉]³⁺ complexes:

:2 Ce (s) + 3 H₂SO₄ (aq) → 2 Ce³⁺ (aq) + 3 (aq) + 3 H₂ (g)

Compounds

Cerium(IV) (ceric) salts are orange red or yellowish, whereas cerium(III) (cerous) salts are usually white or colorless. Both oxidation states absorb ultraviolet light strongly. Cerium(III) can be used to make glasses that are colorless, yet absorb ultraviolet light almost completely. Cerium can be readily detected in rare earth mixtures by a very sensitive qualitative test: addition of ammonia and hydrogen peroxide to an aqueous solution of lanthanides produces a characteristic dark brown color if cerium is present.

Cerium exhibits three oxidation states, +2, +3 and +4. The +2 state is rare and is observed in CeH₂, CeI₂ and CeS. Cerium was named by Berzelius after the dwarf planet Ceres, discovered two years earlier (1801). As originally isolated, cerium was in the form of its oxide, and was named ceria, a term that is still used. The metal itself was too electropositive to be isolated by then-current smelting technology, a characteristic of rare earth metals in general. After the development of electrochemistry by Humphry Davy five years later, the earths soon yielded the metals they contained. Ceria, as isolated in 1803, contained all of the lanthanides present in the cerite ore from Bastnäs, Sweden, and thus only contained about 45% of what is now known to be pure ceria. It was not until Carl Gustaf Mosander succeeded in removing lanthana and "didymia" in the late 1830s, that ceria was obtained pure. Wilhelm Hisinger was a wealthy mine owner and amateur scientist, and sponsor of Berzelius. He owned or controlled the mine at Bastnäs, and had been trying for years to find out the composition of the abundant heavy gangue rock (the "Tungstein of Bastnäs"), now known as cerite, that he had in his mine. Mosander and his family lived for many years in the same house as Berzelius, and Mosander was undoubtedly persuaded by Berzelius to investigate ceria further.

When the rare earths were first discovered, since they were strong bases like the oxides of calcium or magnesium, they were thought to be divalent. Thus, "ceric" cerium was thought to be trivalent, and the oxidation state ratio was therefore thought to be 1.5. Berzelius was annoyed to keep on getting the correct ratio 1.33. He was after all one of the finest analytical chemists in Europe.

In the late 1950s, the Lindsay Chemical Division of American Potash and Chemical Corporation of West Chicago, Illinois, then the largest producer of rare earths in the world, was offering cerium compounds in two purity ranges, "commercial" at 94-97% purity, and "purified", at a reported 99.9+% purity. In their October 1, 1958 price list, one-pound quantities of the oxides were priced at $3.30 or $8.10 respectively for the two purities; the per-pound price for 50-pound quantities were respectively $1.95 or $4.95 for the two grades. Cerium salts were proportionately cheaper, reflecting their lower net content of oxide.

Occurrence

Cerium is the most abundant of the rare earth elements, making up about 0.0046% of the Earth's crust by weight. It is found in a number of minerals including allanite (also known as orthite)—(Ca,Ce,La,Y)₂(Al,Fe)₃(SiO₄)₃(OH), monazite (Ce,La,Th,Nd,Y)PO₄, bastnasite (Ce,La,Y)CO₃F, hydroxylbastnasite (Ce,La,Nd)CO₃(OH,F), rhabdophane (Ce,La,Nd)PO₄-H₂O, zircon (ZrSiO₄), and synchysite Ca(Ce,La,Nd,Y)(CO₃)₂F. Monazite and bastnasite are presently the two most important sources of cerium. Large deposits of monazite, allanite, and bastnasite will supply cerium, thorium, and other rare-earth metals for many years to come.

Production

The mineral mixtures are crushed, ground and treated with hot concentrated sulfuric acid to produce water-soluble sulfates of rare earths. The acidic filtrates are partially neutralized with sodium hydroxide to pH 3–4. Thorium precipitates out of solution as hydroxide and is removed. After that the solution is treated with ammonium oxalate to convert rare earths in to their insoluble oxalates. The oxalates are converted to oxides by annealing. The oxides are dissolved in nitric acid that excludes one of the main components, cerium, whose salts are insoluble in HNO₃. Metallic cerium is prepared by metallothermic reduction techniques, such as by reducing cerium fluoride or chloride with calcium, or by electrolysis of molten cerous chloride or other cerous halides. The metallothermic technique is used to produce high-purity cerium.

Cerium(IV) oxide is considered one of the most efficient agents for precision polishing of optical components. Cerium compounds are also used in the manufacture of glass, both as a component and as a decolorizer. For example, cerium(IV) oxide in combination with titanium(IV) oxide gives a golden yellow color to glass; it also allows for selective absorption of ultraviolet light in glass. Cerium oxide has high refractive index and is added to enamel to make it more opaque.

The photostability of pigments can be enhanced by addition of cerium. It provides pigments with light fastness and prevents clear polymers from darkening in sunlight. Television glass plates are subject to electron bombardment, which tends to darken them by creation of F-center color centers. This effect is suppressed by addition of cerium oxide. Cerium is also an essential component of phosphors used in TV screens and fluorescent lamps.

Precautions

Cerium, like all rare-earth metals, is of low to moderate toxicity. Cerium is a strong reducing agent and ignites spontaneously in air at 65 to 80 °C. Fumes from cerium fires are toxic. Water should not be used to stop cerium fires, as cerium reacts with water to produce hydrogen gas. Workers exposed to cerium have experienced itching, sensitivity to heat, and skin lesions. Animals injected with large doses of cerium have died due to cardiovascular collapse. Cerium(IV) oxide is a powerful oxidizing agent at high temperatures and will react with combustible organic materials. While cerium is not radioactive, the impure commercial grade may contain traces of thorium, which is radioactive. Cerium serves no known biological function.

See also

Organocerium chemistry

References

External links

WebElements.com – Cerium

It's Elemental – The Element Cerium

Cerium Properties and Applications

Chemistry in its element podcast (MP3) from the Royal Society of Chemistry's Chemistry World: Cerium

Category:Chemical elements Category:Lanthanides Category:Cerium Category:Reducing agents

Coordinates	40°37′29″N73°57′8″N
Name	Charlotte Martin
Background	solo_singer
Instrument	Piano, Fender Rhodes, Synth, Vocals, Drum Programming
Genre	Alternative rockPiano pop/rock Experimental
Occupation	Musician, songwriter, producer
Years active	1998–present
Label	RCADinosaur FightEcho FieldTest-Drive
Url	CharlotteMartin.com

Charlotte Ann Martin is an American singer-songwriter, who performs predominantly on the piano. She has written several studio albums, two of which have received mainstream commercial releases, 2004's On Your Shore and 2006's Stromata. In 2009 she released an instrumental piano album titled Piano Trees before releasing her new studio album Dancing on Needles on February 1, 2011.

Biography

Martin grew up in Charleston, Illinois. She won the Miss Illinois Teen USA 1994 title on June 26, 1994 and went on to represent in the Miss Teen USA pageant broadcast live from Biloxi, Mississippi on August 16. Martin graduated from Eastern Illinois University (EIU) in 1998 with a bachelor's degree in vocal performance, majoring in opera. In 1999, Charlotte moved to Los Angeles. On September 30, 2005, she married musician/producer Ken Andrews. Their first child, Ronen Joseph Andrews, was born on May 4, 2008; their second, Stella Jean Andrews was born on March 9, 2011.

Following the birth of Ronen, Martin suffered with the nerve disorder, intercostal neuralgia that left her incapacitated for the better part of a year, causing lengthy delays to the writing and recording process of her latest album "Dancing on Needles".

Martin's father, Joseph Martin, is a music professor at EIU. Her mother, Becky Martin, is an administrator of a program for developmentally disabled adults.

Career

Pre-On Your Shore

Prior to the release of Martin's major-label debut On Your Shore, she had composed two full-length albums and two EPs. Her first foray into songwriting came in the form of Mystery, Magic & Seeds, an album Martin wrote as a result of a friend's death, which she now considers juvenilia, but is available for download from archive.org. Her second album, One Girl Army remained unreleased, though an EP of the same name containing a few selections from the full-length album was released independently, and Martin still performs some of its content live. The masters for this record are now owned by Martin's former record label, RCA Records.

In 2002, Martin independently released a limited edition EP containing eight tracks called Test-Drive Songs, which is now out of print but still available for download at digital outlets including Martin's official site.

In 2003, Martin released another EP entitled In Parentheses on RCA. It contained four tracks, one of which ("Your Armor") would later be included (with an added string arrangement) on On Your Shore. A video for "Your Armor" was released later in the year.

On Your Shore

On August 10, 2004, On Your Shore, Charlotte Martin's first full-length album on a major label, RCA, was released. A video for the single, "Every Time It Rains", was also released.

To help promote the album, Martin toured on the "Chicks With Attitude" tour with Liz Phair, The Cardigans, and Katy Rose in the summer of 2004.

Darkest Hour and Veins

Whilst touring, two EPs were released in preparation for Martin's second album Stromata, showcasing Charlotte's darker and more experimental sound. The first EP, Darkest Hour was available exclusively on her summer tour 2005 and included 6 tracks (including a cover of Depeche Mode's "Judas" and two remixes). The second EP, Veins was pre-released on her 2005 fall tour and then released online in the November of that year.

On May 1, 2006 a DVD of live recordings, titled Something Like A DVD, was released via Musictoday.

Martin co-wrote and contributed vocals to "Glass Breaker", a song by The Crystal Method, released on the soundtrack for the Chris Evans / Jessica Biel movie London.

Stromata

On September 12, 2006, Martin's second full length album on a major label, Stromata, was released worldwide on her husbands' (Ken Andrews) own label Dinosaur Fight Records. Two digital singles were released on iTunes and other outlets in Summer 2006, containing four b-sides from the album. A third digital single was released early in 2007, also available on iTunes. A video for the single "Stromata" was released online and is available for purchase on online outlets. Two bonus tracks were also made exclusively available to iTunes, "Habit" and a remix of the title track. The album showcased a darker sound, with keyboards and other electronic instruments being predominant in the mix (as opposed to the more acoustic piano-based feel of previous records).

On May 1, 2007, Something Like A DVD was re-released as a DVD/CD dual package, including exclusive b-sides to Stromata and backstage footage surrounding the making of On Your Shore. The DVD is described as being the bridging piece between On Your Shore and Stromata by Martin's publicity releases.

Martin co-wrote and contributed vocals to the song "Sweet Things" on DJ Tiësto's 2007 album Elements of Life. She co-wrote and contributed vocals and piano to the song "Is This How Love's Supposed to Feel" on Ben Lee's 2007 album Ripe. She co-wrote and contributed vocals to the song "Feed the Monster" for BT's forthcoming album.

Orphans and Piano Trees

On September 2, 2008, Martin confirmed the release of a new studio EP, Orphans. A video blog was posted several days later on September 8 revealing more details on the project, which contains b-sides and other material left off On Your Shore and Stromata (hence the EP name Orphans). Most of the tracks are re-recorded or remastered, such as the Stromata b-side "Habit" and two tracks from her EP Test Drive Songs ("Many Rivers" and "Raven"). "Galaxies" and "Is This Called Desire" are two previously unheard tracks featured on the EP, along with old live fan favorite "The Stalker Song" (aka: "I'm Normal, Please Date Me") appearing for the first time in studio form.

In a first for Martin, a contest was held for her fans to design the cover art for the EP. Orphans was released on 11 November 2008 and is available on American iTunes.

In 2009, she released the instrumental album Piano Trees, a collection of improvised piano songs.

Dancing On Needles

On February 1, 2011, Martin released her fourth album, Dancing on Needles. Produced by Ken Andrews (who had previously worked with Pete Yorn and Beck), the rapturous album traces Martin's heartbreaking struggle with intercostal neuralgia, a nerve disorder that left her incapacitated for much of the past year. "It was the most difficult period of my life," Martin stated. "The pain was excruciating. I saw countless doctors, was misdiagnosed countless times and prescribed countless medications. Nothing seemed to help. Forget about not being able to work; getting out of bed was a major undertaking. Worst of all, I couldn’t nurse, or even lift, my baby. As a new mother, that was devastating".

The album was released on Martin's Test-Drive Records and was preceded by the single "Volcano". Martin's official website announced the video for the single, available exclusively on YouTube on the same day the album was released digitally.

Discography

A complete list of Martin's discography is available on her official site.

Albums

Mystery, Magic & Seeds (1998)

One Girl Army (2001)

On Your Shore (2004)

Stromata (2006)

Reproductions (2007)

Piano Trees (2009)

Dancing on Needles (2011)

EPs

One Girl Army (2002)

Test-Drive Songs (2002)

In Parentheses (2003)

Darkest Hour (2005)

Veins (2005)

Stromata (EP version) (2006)

Rarities #1-#6 (2006–2009)

Orphans (2008)

DVDs

Something Like a DVD (2005, re-released in 2007 as Dual DVD/CD set with B-Sides from On Your Shore and Stromata.)

Additional credits

Martin's song "Beautiful Life" from On Your Shore appears in the Maxis computer game (The Sims 2 expansion pack), translated into the game's fictional language of Simlish. "Keep Me In Your Pocket" from Stromata appears in the same fashion in .

Martin co-wrote and recorded "Glass Breaker" with The Crystal Method. The song appears on the London Movie Soundtrack.

Martin has released six "rarity" EPs, called the Rarities series, available for purchase only at live shows. These contain previously unreleased or hard-to-find material, and sparked something of a scavenger hunt among fans due to their limited availability. One of the songs featured, "Cool Killer," is home-recorded and features Martin scolding her dog Hugo in the background.

Martin's voice is featured on the Mae album The Everglow, in the tracks "Prologue" and "Epilogue."

Martin is the vocalist/pianist and a co-writer in the song "Greater Lights" on the soundtrack of the video game Advent Rising.

Martin recorded "Bring On the Day" for the film Sweet Home Alabama starring Reese Witherspoon in 2002, and the song is featured in the opening sequence of the movie. The song can also be found on the soundtrack to the film.

Martin is credited with additional vocals on the song "Inhuman" by Thousand Foot Krutch, from their album The Flame in All of Us.

Martin's songs "Veins" (from the Veins EP) and "The Dance" (from Stromata) were used during the third and fourth seasons of the hit television show So You Think You Can Dance.

Martin co-wrote and played piano for the song "Is This How Love's Supposed to Feel" on the Ben Lee album Ripe.

Martin co-wrote and sang 'Sweet Things" on the 2007 "Tiesto" album "Elements of Life".

References

External links

Official website

Internet Archive's live music archive">Charlotte Martin collection on the Internet Archive's live music archive

Charlotte Martin live on WOXY.com, April 4, 2006

Charlotte Martin live on WOXY.com, November 3, 2006

Category:1976 births Category:Living people Category:American singer-songwriters Category:American female singers Category:Eastern Illinois University alumni Category:Musicians from Illinois Category:Miss Teen USA 1994 delegates Category:People from Coles County, Illinois