Promethium compounds

Last updated

Promethium compounds are compounds containing the element promethium, which normally take the +3 oxidation state. Promethium belongs to the cerium group of lanthanides and is chemically very similar to the neighboring elements. [1] Because of its instability, chemical studies of promethium are incomplete. Even though a few compounds have been synthesized, they are not fully studied; in general, they tend to be pink or red in color. [2] [3] Treatment of acidic solutions containing Pm3+ ions with ammonia results in a gelatinous light-brown sediment of hydroxide, Pm(OH)3, which is insoluble in water. [4] When dissolved in hydrochloric acid, a water-soluble yellow salt, PmCl3, is produced; [4] similarly, when dissolved in nitric acid, a nitrate results, Pm(NO3)3. The latter is also well-soluble; when dried, it forms pink crystals, similar to Nd(NO3)3. [4] The electron configuration for Pm3+ is [Xe] 4f4, and the color of the ion is pink. The ground state term symbol is 5I4. [5] The sulfate is slightly soluble, like the other cerium group sulfates. Cell parameters have been calculated for its octahydrate; they lead to conclusion that the density of Pm2(SO4)3·8 H2O is 2.86 g/cm3. [6] The oxalate, Pm2(C2O4)3·10 H2O, has the lowest solubility of all lanthanide oxalates. [7]

Unlike the nitrate, the oxide is similar to the corresponding samarium salt and not the neodymium salt. As-synthesized, e.g. by heating the oxalate, it is a white or lavender-colored powder with disordered structure. [4] This powder crystallizes in a cubic lattice upon heating to 600 °C. Further annealing at 800 °C and then at 1750 °C irreversibly transforms it to monoclinic and hexagonal phases, respectively, and the last two phases can be interconverted by adjusting the annealing time and temperature. [8]

Formulasymmetry space group No Pearson symbol a (pm)b (pm)c (pm)Zdensity,
g/cm3
α-Pm dhcp [9] [10] P63/mmc194hP4365365116547.26
β-Pm bcc [10] Fm3m225cF441041041046.99
Pm2O3cubic [8] Ia3206cI80109910991099166.77
Pm2O3monoclinic [8] C2/m12mS30142236589167.40
Pm2O3hexagonal [8] P3m1164hP5380.2380.2595.417.53

Promethium forms only one stable oxidation state, +3, in the form of ions; this is in line with other lanthanides. According to its position in the periodic table, the element cannot be expected to form stable +4 or +2 oxidation states; treating chemical compounds containing Pm3+ ions with strong oxidizing or reducing agents showed that the ion is not easily oxidized or reduced. [1]

Promethium halides [11]
Formulacolorcoordination
number		symmetry space group No Pearson symbol m.p. (°C)
PmF3Purple-pink11hexagonalP3c1165hP241338
PmCl3Lavender9hexagonalP63/mc176hP8655
PmBr3Red8orthorhombicCmcm63oS16624
α-PmI3Red8orthorhombicCmcm63oS16α→β
β-PmI3Red6rhombohedralR3148hR24695

Bibliography

Related Research Articles

<span class="mw-page-title-main">Promethium</span> Chemical element, symbol Pm and atomic number 61

Promethium is a chemical element; it has symbol Pm and atomic number 61. All of its isotopes are radioactive; it is extremely rare, with only about 500–600 grams naturally occurring in Earth's crust at any given time. Promethium is one of only two radioactive elements that are followed in the periodic table by elements with stable forms, the other being technetium. Chemically, promethium is a lanthanide. Promethium shows only one stable oxidation state of +3.

<span class="mw-page-title-main">Terbium</span> Chemical element, symbol Tb and atomic number 65

Terbium is a chemical element; it has symbol Tb and atomic number 65. It is a silvery-white, rare earth metal that is malleable, and ductile. The ninth member of the lanthanide series, terbium is a fairly electropositive metal that reacts with water, evolving hydrogen gas. Terbium is never found in nature as a free element, but it is contained in many minerals, including cerite, gadolinite, monazite, xenotime and euxenite.

<span class="mw-page-title-main">Iron(III)</span> The element iron in its +3 oxidation state

In chemistry, iron (III) refers to the element iron in its +3 oxidation state. In ionic compounds (salts), such an atom may occur as a separate cation (positive ion) denoted by Fe3+.

<span class="mw-page-title-main">Praseodymium</span> Chemical element, symbol Pr and atomic number 59

Praseodymium is a chemical element; it has symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for its magnetic, electrical, chemical, and optical properties. It is too reactive to be found in native form, and pure praseodymium metal slowly develops a green oxide coating when exposed to air.

<span class="mw-page-title-main">Cerium(IV) sulfate</span> Chemical compound

Cerium(IV) sulfate, also called ceric sulfate, is an inorganic compound. It exists as the anhydrous salt Ce(SO4)2 as well as a few hydrated forms: Ce(SO4)2(H2O)x, with x equal to 4, 8, or 12. These salts are yellow to yellow/orange solids that are moderately soluble in water and dilute acids. Its neutral solutions slowly decompose, depositing the light yellow oxide CeO2. Solutions of ceric sulfate have a strong yellow color. The tetrahydrate loses water when heated to 180-200 °C.

<span class="mw-page-title-main">Uranyl nitrate</span> Chemical compound

Uranyl nitrate is a water-soluble yellow uranium salt with the formula UO2(NO3)2 · n H2O. The hexa-, tri-, and dihydrates are known. The compound is mainly of interest because it is an intermediate in the preparation of nuclear fuels.

<span class="mw-page-title-main">Holmium(III) oxide</span> Chemical compound

Holmium(III) oxide, or holmium oxide is a chemical compound of a rare-earth element holmium and oxygen with the formula Ho2O3. Together with dysprosium(III) oxide (Dy2O3), holmium oxide is one of the most powerfully paramagnetic substances known. The oxide, also called holmia, occurs as a component of the related erbium oxide mineral called erbia. Typically, the oxides of the trivalent lanthanides coexist in nature, and separation of these components requires specialized methods. Holmium oxide is used in making specialty colored glasses. Glass containing holmium oxide and holmium oxide solutions have a series of sharp optical absorption peaks in the visible spectral range. They are therefore traditionally used as a convenient calibration standard for optical spectrophotometers.

<span class="mw-page-title-main">Silver oxide</span> Chemical compound

Silver oxide is the chemical compound with the formula Ag2O. It is a fine black or dark brown powder that is used to prepare other silver compounds.

<span class="mw-page-title-main">Uranyl</span> Oxycation of uranium

The uranyl ion is an oxycation of uranium in the oxidation state +6, with the chemical formula UO2+
2. It has a linear structure with short U–O bonds, indicative of the presence of multiple bonds between uranium and oxygen. Four or more ligands may be bound to the uranyl ion in an equatorial plane around the uranium atom. The uranyl ion forms many complexes, particularly with ligands that have oxygen donor atoms. Complexes of the uranyl ion are important in the extraction of uranium from its ores and in nuclear fuel reprocessing.

<span class="mw-page-title-main">Iron(III) nitrate</span> Chemical compound

Iron(III) nitrate, or ferric nitrate, is the name used for a series of inorganic compounds with the formula Fe(NO3)3.(H2O)n. Most common is the nonahydrate Fe(NO3)3.(H2O)9. The hydrates are all pale colored, water-soluble paramagnetic salts.

<span class="mw-page-title-main">Cerium</span> Chemical element, symbol Ce and atomic number 58

Cerium is a chemical element; it has symbol Ce and atomic number 58. Cerium is a soft, ductile, and silvery-white metal that tarnishes when exposed to air. Cerium is the second element in the lanthanide series, and while it often shows the oxidation state of +3 characteristic of the series, it also has a stable +4 state that does not oxidize water. It is also considered one of the rare-earth elements. Cerium has no known biological role in humans but is not particularly toxic, except with intense or continued exposure.

<span class="mw-page-title-main">Lead compounds</span> Type of compound

Compounds of lead exist with lead in two main oxidation states: +2 and +4. The former is more common. Inorganic lead(IV) compounds are typically strong oxidants or exist only in highly acidic solutions.

<span class="mw-page-title-main">Cerium nitrates</span> Chemical compound

Cerium nitrate refers to a family of nitrates of cerium in the +3 or +4 oxidation state. Often these compounds contain water, hydroxide, or hydronium ions in addition to cerium and nitrate. Double nitrates of cerium also exist.

<span class="mw-page-title-main">Thorium(IV) nitrate</span> Chemical compound

Thorium(IV) nitrate is a chemical compound, a salt of thorium and nitric acid with the formula Th(NO3)4. A white solid in its anhydrous form, it can form tetra- and pentahydrates. As a salt of thorium it is weakly radioactive.

<span class="mw-page-title-main">Neodymium(III) fluoride</span> Inorganic chemical compound

Neodymium(III) fluoride is an inorganic chemical compound of neodymium and fluorine with the formula NdF3. It is a purplish pink colored solid with a high melting point.

<span class="mw-page-title-main">Iron(II) nitrate</span> Chemical compound

Iron(II) nitrate is the nitrate salt of iron(II). It is commonly encountered as the green hexahydrate, Fe(NO3)2·6H2O, which is a metal aquo complex, however it is not commercially available unlike iron(III) nitrate due to its instability to air. The salt is soluble in water serves as a ready source of ferrous ions.

Promethium(III) nitrate is an inorganic compound, a salt of promethium and nitric acid with the chemical formula Pm(NO3)3. The compound is radioactive, soluble in water and forms crystalline hydrates.

<span class="mw-page-title-main">Europium compounds</span> Compounds with at least one europium atom

Europium compounds are compounds formed by the lanthanide metal europium (Eu). In these compounds, europium generally exhibits the +3 oxidation state, such as EuCl3, Eu(NO3)3 and Eu(CH3COO)3. Compounds with europium in the +2 oxidation state are also known. The +2 ion of europium is the most stable divalent ion of lanthanide metals in aqueous solution. Many europium compounds fluoresce under ultraviolet light due to the excitation of electrons to higher energy levels. Lipophilic europium complexes often feature acetylacetonate-like ligands, e.g., Eufod.

Cerium compounds are compounds containing the element cerium (Ce), a lanthanide. Cerium exists in two main oxidation states, Ce(III) and Ce(IV). This pair of adjacent oxidation states dominates several aspects of the chemistry of this element. Cerium(IV) aqueous solutions may be prepared by reacting cerium(III) solutions with the strong oxidizing agents peroxodisulfate or bismuthate. The value of E⦵(Ce4+/Ce3+) varies widely depending on conditions due to the relative ease of complexation and hydrolysis with various anions, although +1.72 V is representative. Cerium is the only lanthanide which has important aqueous and coordination chemistry in the +4 oxidation state.

References

  1. 1 2 Lavruk︠h︡ina & Pozdni︠a︡kov 1970, p. 120.
  2. ↑ Emsley, J. (2011). Nature’s Building Blocks: An A-Z Guide to the Elements. OUP Oxford. p. 429.
  3. ↑ promethium. Encyclopædia Britannica Online
  4. 1 2 3 4 Lavruk︠h︡ina & Pozdni︠a︡kov 1970, p. 121.
  5. ↑ Aspinall, H. C. (2001). Chemistry of the f-block elements. Gordon & Breach. p. 34, Table 2.1. ISBN   978-9056993337.
  6. ↑ Lavruk︠h︡ina & Pozdni︠a︡kov 1970, p. 122.
  7. ↑ Lavruk︠h︡ina & Pozdni︠a︡kov 1970, p. 123.
  8. 1 2 3 4 Chikalla, T. D.; McNeilly, C. E.; Roberts, F. P. (1972). "Polymorphic Modifications of Pm2O3". Journal of the American Ceramic Society. 55 (8): 428. doi:10.1111/j.1151-2916.1972.tb11329.x.
  9. ↑ Pallmer, P. G.; Chikalla, T. D. (1971). "The crystal structure of promethium". Journal of the Less Common Metals. 24 (3): 233. doi:10.1016/0022-5088(71)90101-9.
  10. 1 2 Gschneidner Jr., K.A. (2005). "Physical Properties of the rare earth metals" (PDF). In Lide, D. R. (ed.). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton, FL: CRC Press. ISBN   978-0-8493-0486-6. Archived from the original (PDF) on 2012-09-18. Retrieved 2012-06-20.
  11. ↑ Cotton, Simon (2006). Lanthanide And Actinide Chemistry. John Wiley & Sons. p. 117. ISBN   978-0-470-01006-8.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.