Rhodium

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Rhodium, 45Rh
Rhodium powder pressed melted.jpg
Rhodium
Pronunciation /ˈroʊdiəm/ ​(ROH-dee-əm)
AppearanceSilvery white metallic
Standard atomic weight Ar°(Rh)
Rhodium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Co
↑
Rh
↓
Ir
ruthenium ← rhodium → palladium
Atomic number (Z)45
Group group 9
Period period 5
Block   d-block
Electron configuration [ Kr ] 4d8 5s1
Electrons per shell2, 8, 18, 16, 1
Physical properties
Phase at  STP solid
Melting point 2237  K ​(1964 °C,​3567 °F)
Boiling point 3968 K​(3695 °C,​6683 °F)
Density (at 20° C)12.423 g/cm3 [3]
when liquid (at  m.p.)10.7 g/cm3
Heat of fusion 26.59  kJ/mol
Heat of vaporization 493 kJ/mol
Molar heat capacity 24.98 J/(mol·K)
Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)228824962749306334053997
Atomic properties
Oxidation states common: +3
−3, [4] −1, [5] 0, [6] +1, [5] +2, [5] +4, [5] +5, [5] +6, [5] +7 [7]
Electronegativity Pauling scale: 2.28
Ionization energies
  • 1st: 719.7 kJ/mol
  • 2nd: 1740 kJ/mol
  • 3rd: 2997 kJ/mol
Atomic radius empirical:134  pm
Covalent radius 142±7 pm
Rhodium spectrum visible.png
Spectral lines of rhodium
Other properties
Natural occurrence primordial
Crystal structure ​ face-centered cubic (fcc)(cF4)
Lattice constant
Cubic-face-centered.svg
a = 380.34 pm (at 20 °C) [3]
Thermal expansion 8.46×10−6/K (at 20 °C) [3]
Thermal conductivity 150 W/(m⋅K)
Electrical resistivity 43.3 nΩ⋅m(at 0 °C)
Magnetic ordering paramagnetic [8]
Molar magnetic susceptibility +111.0×10−6 cm3/mol(298 K) [9]
Young's modulus 380 GPa
Shear modulus 150 GPa
Bulk modulus 275 GPa
Speed of sound thin rod4700 m/s(at 20 °C)
Poisson ratio 0.26
Mohs hardness 6.0
Vickers hardness 1100–8000 MPa
Brinell hardness 980–1350 MPa
CAS Number 7440-16-6
History
Discovery and first isolation William Hyde Wollaston (1804)
Isotopes of rhodium
Main isotopes [10] Decay
abun­dance half-life (t1/2) mode pro­duct
99Rh synth 16.1 d β+ 99Ru
101Rhsynth4.07 y ε 101Ru
101mRhsynth4.343 dε 101Ru
IT 101Rh
102Rhsynth207 dβ+ 102Ru
β− 102Pd
102mRhsynth3.742 yβ+102Ru
IT102Rh
103Rh100% stable
105Rhsynth35.341 hβ− 105Pd
Symbol category class.svg  Category: Rhodium
| references

Rhodium is a chemical element; it has symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isotope, which is 103Rh. Naturally occurring rhodium is usually found as a free metal or as an alloy with similar metals and rarely as a chemical compound in minerals such as bowieite and rhodplumsite. It is one of the rarest and most valuable precious metals. Rhodium is a group 9 element. (cobalt group)

Contents

Rhodium is found in platinum or nickel ores with the other members of the platinum group metals. It was discovered in 1803 by William Hyde Wollaston in one such ore, and named for the rose color of one of its chlorine compounds.

The element's major use (consuming about 80% of world rhodium production) is as one of the catalysts in the three-way catalytic converters in automobiles. Because rhodium metal is inert against corrosion and most aggressive chemicals, and because of its rarity, rhodium is usually alloyed with platinum or palladium and applied in high-temperature and corrosion-resistive coatings. White gold is often plated with a thin rhodium layer to improve its appearance, while sterling silver is often rhodium-plated to resist tarnishing.

Rhodium detectors are used in nuclear reactors to measure the neutron flux level. Other uses of rhodium include asymmetric hydrogenation used to form drug precursors and the processes for the production of acetic acid.

History

William Hyde Wollaston Wollaston William Hyde Jackson color.jpg
William Hyde Wollaston

Rhodium (from Greek : ῥόδονrhodon, meaning 'rose') was discovered in 1803 by William Hyde Wollaston, [11] soon after he discovered palladium. [12] [13] [14] He used crude platinum ore presumably obtained from South America. [15] His procedure dissolved the ore in aqua regia and neutralized the acid with sodium hydroxide (NaOH). He then precipitated the platinum as ammonium chloroplatinate by adding ammonium chloride (NH
4Cl). Most other metals like copper, lead, palladium, and rhodium were precipitated with zinc. Diluted nitric acid dissolved all but palladium and rhodium. Of these, palladium dissolved in aqua regia but rhodium did not, [16] and the rhodium was precipitated by the addition of sodium chloride as Na
3[RhCl
6]·nH
2O. After being washed with ethanol, the rose-red precipitate was reacted with zinc, which displaced the rhodium in the ionic compound and thereby released the rhodium as free metal. [17]

For decades, the rare element had only minor applications; for example, by the turn of the century, rhodium-containing thermocouples were used to measure temperatures up to 1800 °C. [18] [19] They have exceptionally good stability in the temperature range of 1300 to 1800 °C. [20]

The first major application was electroplating for decorative uses and as corrosion-resistant coating. [21] The introduction of the three-way catalytic converter by Volvo in 1976 increased the demand for rhodium. The previous catalytic converters used platinum or palladium, while the three-way catalytic converter used rhodium to reduce the amount of NOx in the exhaust. [22] [23] [24]

Characteristics

Z Element No. of electrons/shell
27cobalt2, 8, 15, 2
45rhodium2, 8, 18, 16, 1
77iridium2, 8, 18, 32, 15, 2
109meitnerium2, 8, 18, 32, 32, 15, 2 (predicted)

Rhodium is a hard, silvery, durable metal that has a high reflectance. Rhodium metal does not normally form an oxide, even when heated. [25] Oxygen is absorbed from the atmosphere only at the melting point of rhodium, but is released on solidification. [26] Rhodium has both a higher melting point and lower density than platinum. It is not attacked by most acids: it is completely insoluble in nitric acid and dissolves slightly in aqua regia.

Rhodium belongs to group 9 of the periodic table, but exhibits an atypical ground state valence electron configuration for that group. Like neighboring elements niobium (41), ruthenium (44), and palladium (46), it only has one electron in its outermost s orbital.

Chemical properties

Structure of Wilkinson's catalyst (Ph = phenyl = C6H5). Wilkinson's-catalyst-2D.png
Structure of Wilkinson's catalyst (Ph = phenyl = C6H5).
Oxidation states
of rhodium
+0Rh
4(CO)
12
+1RhCl(PH
3)
2
+2Rh
2(O
2CCH
3)
4
+3RhCl
3, Rh
2O
3
+4RhO
2
+5RhF
5, Sr
3LiRhO
6
+6RhF
6

The common oxidation states of rhodium are +3 and +1. Oxidation states 0, +2, and +4 are also well known. [27] A few complexes at still higher oxidation states are known. [28]

The rhodium oxides include Rh
2O
3 , RhO
2 , RhO
2·xH
2O, Na
2RhO
3, Sr
3LiRhO
6 and Sr
3NaRhO
6. [29] None are of technological significance.

All the Rh(III) halides are known but the hydrated trichloride is most frequently encountered. It is also available in an anhydrous form, which is somewhat refractory. Other rhodium(III) chlorides include sodium hexachlororhodate, Na3RhCl6, and pentaamminechlororhodium dichloride, [Rh(NH3)5Cl]Cl2. They are used in the recycling and purification of this very expensive metal. Heating a methanolic solution of hydrated rhodium trichloride with sodium acetate give the blue-green rhodium(II) acetate, Rh2(O2CCH3)4, which features a Rh-Rh bond. This complex and related rhodium(II) trifluoroacetate have attracted attention as catalysts for cyclopropanation reactions. Hydrated rhodium trichloride is reduced by carbon monoxide, ethylene, and trifluorophosphine to give rhodium(I) complexes Rh2Cl2L4 (L = CO, C2H4, PF3). When treated with triphenylphosphine, hydrated rhodium trichloride converts to the maroon-colored RhCl(P(C6H5)3)3, which is known as Wilkinson's catalyst. Reduction of rhodium carbonyl chloride gives hexarhodium hexadecacarbonyl, Rh6(CO)16, and tetrarhodium dodecacarbonyl, Rh4(CO)12, the two most common Rh(0) complexes.

As for other metals, rhodium forms high oxidation state binary fluorides. These include rhodium pentafluoride, a tetrameric complex with the true formula Rh4F20) and rhodium hexafluoride. [30]

Isotopes

Naturally occurring rhodium is composed of only one isotope, 103Rh. The most stable radioisotopes are 101Rh with a half-life of 3.3 years, 102Rh with a half-life of 207 days, 102mRh with a half-life of 2.9 years, and 99Rh with a half-life of 16.1 days. Twenty other radioisotopes have been characterized with atomic weights ranging from 92.926 u (93Rh) to 116.925 u (117Rh). Most of these have half-lives shorter than an hour, except 100Rh (20.8 hours) and 105Rh (35.36 hours). Rhodium has numerous meta states, the most stable being 102mRh (0.141 MeV) with a half-life of about 2.9 years and 101mRh (0.157 MeV) with a half-life of 4.34 days (see isotopes of rhodium). [31]

In isotopes weighing less than 103 (the stable isotope), the primary decay mode is electron capture and the primary decay product is ruthenium. In isotopes greater than 103, the primary decay mode is beta emission and the primary product is palladium. [32]

Occurrence

Rhodium is one of the rarest elements in the Earth's crust, comprising an estimated 0.0002 parts per million (2 × 10−10). [33] Its rarity affects its price and its use in commercial applications. The concentration of rhodium in nickel meteorites is typically 1 part per billion. [34] Rhodium has been measured in some potatoes with concentrations between 0.8 and 30 ppt. [35]

Mining and price

Rh price evolution Rh price.png
Rh price evolution
Rhodium daily price 1992-2022 Rhodium daily Price 1992-2022.webp
Rhodium daily price 1992–2022

Rhodium ores are a mixture with other metals such as palladium, silver, platinum, and gold. Few rhodium minerals are known. The separation of rhodium from the other metals poses significant challenges. Principal sources are located in South Africa, river sands of the Ural Mountains in Russia, and in North America, especially the copper-nickel sulfide mining area of the Sudbury, Ontario, region. Although the rhodium abundance at Sudbury is very small, the large amount of processed nickel ore makes rhodium recovery cost-effective.

The main exporter of rhodium is South Africa (approximately 80% in 2010) followed by Russia. [36] The annual world production is 30 tonnes. The price of rhodium is highly variable.

Used nuclear fuels

Rhodium is a fission product of uranium-235: each kilogram of fission product contains a significant amount of the lighter platinum group metals. Used nuclear fuel is therefore a potential source of rhodium, but the extraction is complex and expensive, and the presence of rhodium radioisotopes requires a period of cooling storage for multiple half-lives of the longest-lived isotope (101Rh with a half-life of 3.3 years, and 102mRh with a half-life of 2.9 years), or about 10 years. These factors make the source unattractive and no large-scale extraction has been attempted. [37] [38] [39]

Applications

The primary use of this element is in automobiles as a catalytic converter, changing harmful unburned hydrocarbons, carbon monoxide, and nitrogen oxide exhaust emissions into less noxious gases. Of 30,000 kg of rhodium consumed worldwide in 2012, 81% (24,300 kg) went into this application, and 8,060 kg was recovered from old converters. About 964 kg of rhodium was used in the glass industry, mostly for production of fiberglass and flat-panel glass, and 2,520 kg was used in the chemical industry. [36] [40]

2 NO
x → xO
2 + N
2

In 2008, net demand (with the recycling accounted for) of rhodium for automotive converters made up 84% of the world usage, [41] with the number fluctuating around 80% in 2015−2021. [42]

Carbonylation

Tris(triphenylphosphine)rhodium carbonyl hydride, a widely used catalyst for hydroformylation (Ph = C6H5) HRh(CO)P3again.png
Tris(triphenylphosphine)rhodium carbonyl hydride, a widely used catalyst for hydroformylation (Ph = C6H5)

Rhodium catalysts are used in some industrial processes, notably those involving carbon monoxide. In the Monsanto process, rhodium iodides catalyze the carbonylation of methanol to produce acetic acid. [43] This technology has been significantly displaced by the iridium-based Cativa process, which effects the same conversion but more efficiently. Rhodium-based complexes are the dominant catalysts for hydroformylation, which converts alkenes to aldehydes according to the following equation: [44] [45]

RCH=CH2 + H2 + CO → RCH2−CH2CHO

Rh-based hydroformylation underpins the industrial production of products as diverse as detergents, fragrances, and some drugs. Originally hydroformylation relied on much cheaper cobalt carbonyl-based catalysts, but that technology has largely been eclipsed by rhodium-based catalysts despite the cost differential.

Rhodium is also known to catalyze many reactions involving hydrogen gas and hydrosilanes. These include hydrogenations and hydrosilylations of alkenes. [46] Rhodium metal, but not rhodium complexes, catalyzes the hydrogenation of benzene to cyclohexane. [47]

Ornamental uses

Rhodium finds use in jewelry and for decorations. It is electroplated on white gold and platinum to give it a reflective white surface at time of sale, after which the thin layer wears away with use. This is known as rhodium flashing in the jewelry business. It may also be used in coating sterling silver to protect against tarnish (silver sulfide, Ag2S, produced from atmospheric hydrogen sulfide, H2S). Solid (pure) rhodium jewelry is very rare, more because of the difficulty of fabrication (high melting point and poor malleability) than because of the high price. [48] The high cost ensures that rhodium is applied only as an electroplate. Rhodium has also been used for honors or to signify elite status, when more commonly used metals such as silver, gold or platinum were deemed insufficient. In 1979 the Guinness Book of World Records gave Paul McCartney a rhodium-plated disc for being history's all-time best-selling songwriter and recording artist. [49]

Other uses

Rhodium is used as an alloying agent for hardening and improving the corrosion resistance [25] of platinum and palladium. These alloys are used in furnace windings, bushings for glass fiber production, thermocouple elements, electrodes for aircraft spark plugs, and laboratory crucibles. [50] Other uses include:

In automobile manufacturing, rhodium is also used in the construction of headlight reflectors. [55]

Precautions

Rhodium
Hazards
GHS labelling:
H413
P273, P501 [56]
NFPA 704 (fire diamond)
NFPA 704.svgHealth 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chlorideFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
0
0

Being a noble metal, pure rhodium is inert and harmless in elemental form. [57] However, chemical complexes of rhodium can be reactive. For rhodium chloride, the median lethal dose (LD50) for rats is 198 mg (RhCl
3) per kilogram of body weight. [58] Like the other noble metals, rhodium has not been found to serve any biological function.

People can be exposed to rhodium in the workplace by inhalation. The Occupational Safety and Health Administration (OSHA) has specified the legal limit (Permissible exposure limit) for rhodium exposure in the workplace at 0.1 mg/m3 over an 8-hour workday, and the National Institute for Occupational Safety and Health (NIOSH) has set the recommended exposure limit (REL), at the same level. At levels of 100 mg/m3, rhodium is immediately dangerous to life or health. [59] For soluble compounds, the PEL and REL are both 0.001 mg/m3. [60]

See also

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References

  1. ↑ "Standard Atomic Weights: Rhodium". CIAAW. 2017.
  2. ↑ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN   1365-3075.
  3. 1 2 3 Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN   978-1-62708-155-9.
  4. ↑ Ellis J E. Highly Reduced Metal Carbonyl Anions: Synthesis, Characterization, and Chemical Properties. Adv. Organomet. Chem, 1990, 31: 1-51.
  5. 1 2 3 4 5 6 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN   978-0-08-037941-8.
  6. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 1140. ISBN   978-0-08-037941-8.
  7. ↑ Rh(VII) is known in the RhO3+ cation, see Da Silva Santos, Mayara; Stüker, Tony; Flach, Max; Ablyasova, Olesya S.; Timm, Martin; von Issendorff, Bernd; Hirsch, Konstantin; Zamudio‐Bayer, Vicente; Riedel, Sebastian; Lau, J. Tobias (2022). "The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3]+". Angew. Chem. Int. Ed. 61 (38): e202207688. doi:10.1002/anie.202207688. PMC   9544489 . PMID   35818987.
  8. ↑ Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN   0-8493-0486-5.
  9. ↑ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN   0-8493-0464-4.
  10. ↑ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
  11. ↑ Wollaston, W. H. (1804). "On a New Metal, Found in Crude Platina". Philosophical Transactions of the Royal Society of London . 94: 419–430. doi: 10.1098/rstl.1804.0019 .
  12. ↑ Griffith, W. P. (2003). "Rhodium and Palladium – Events Surrounding Its Discovery". Platinum Metals Review. 47 (4): 175–183. doi: 10.1595/003214003X474175183 .
  13. ↑ Wollaston, W. H. (1805). "On the Discovery of Palladium; With Observations on Other Substances Found with Platina". Philosophical Transactions of the Royal Society of London . 95: 316–330. doi: 10.1098/rstl.1805.0024 .
  14. ↑ Usselman, Melvyn (1978). "The Wollaston/Chenevix controversy over the elemental nature of palladium: A curious episode in the history of chemistry". Annals of Science. 35 (6): 551–579. doi:10.1080/00033797800200431.
  15. ↑ Lide, David R. (2004). CRC handbook of chemistry and physics: a ready-reference book of chemical and physical data . Boca Raton: CRC Press. pp.  4–26. ISBN   978-0-8493-0485-9.
  16. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 1113. ISBN   978-0-08-037941-8.
  17. ↑ Griffith, W. P. (2003). "Bicentenary of Four Platinum Group Metals: Osmium and iridium – events surrounding their discoveries". Platinum Metals Review. 47 (4): 175–183. doi: 10.1595/003214003X474175183 .
  18. ↑ Hulett, G. A.; Berger, H. W. (1904). "Volatilization of Platinum". Journal of the American Chemical Society. 26 (11): 1512–1515. doi:10.1021/ja02001a012. Archived (PDF) from the original on 24 January 2024 – via Zenodo.
  19. ↑ ASTM Committee E.2.0. on Temperature Measurement (1993). "Platinum Type". Manual on the use of thermocouples in temperature measurement. ASTM Special Technical Publication. ASTM International. Bibcode:1981mutt.book.....B. ISBN   978-0-8031-1466-1.[ permanent dead link ]
  20. ↑ J. V. Pearce, F. Edler, C. J. Elliott, A. Greenen, P. M. Harris, C. G. Izquierdo, Y. G. Kim, M. J. Martin, I. M. Smith, D. Tucker and R. I. Veitcheva, A systematic investigation of the thermoelectric stability of Pt-Rh thermocouples between 1300 °C and 1500 °C, METROLOGIA, 2018, Volume: 55 Issue: 4 Pages: 558-567
  21. ↑ Kushner, Joseph B. (1940). "Modern rhodium plating". Metals and Alloys. 11: 137–140.
  22. ↑ Amatayakul, W.; Ramnäs, Olle (2001). "Life cycle assessment of a catalytic converter for passenger cars". Journal of Cleaner Production. 9 (5): 395. Bibcode:2001JCPro...9..395A. doi:10.1016/S0959-6526(00)00082-2.
  23. ↑ Heck, R.; Farrauto, Robert J. (2001). "Automobile exhaust catalysts". Applied Catalysis A: General. 221 (1–2): 443–457. doi:10.1016/S0926-860X(01)00818-3.
  24. ↑ Heck, R.; Gulati, Suresh; Farrauto, Robert J. (2001). "The application of monoliths for gas phase catalytic reactions". Chemical Engineering Journal. 82 (1–3): 149–156. Bibcode:2001ChEnJ..82..149H. doi:10.1016/S1385-8947(00)00365-X.
  25. 1 2 Cramer, Stephen D.; Covino, Bernard S. Jr., eds. (1990). ASM handbook. Materials Park, OH: ASM International. pp. 393–396. ISBN   978-0-87170-707-9.
  26. ↑ Emsley, John (2001). Nature's Building Blocks ((Hardcover, First Edition) ed.). Oxford University Press. p.  363. ISBN   978-0-19-850340-8.
  27. ↑ Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (1985). Lehrbuch der Anorganischen Chemie (91–100 ed.). Walter de Gruyter. pp. 1056–1057. ISBN   978-3-11-007511-3.
  28. ↑ Da Silva Santos, Mayara; Stüker, Tony; Flach, Max; Ablyasova, Olesya S.; Timm, Martin; von Issendorff, Bernd; Hirsch, Konstantin; Zamudio-Bayer, Vicente; Riedel, Sebastian; Lau, J. Tobias (2022). "The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3]+". Angewandte Chemie International Edition. 61 (38): e202207688. doi:10.1002/anie.202207688. PMC   9544489 . PMID   35818987.
  29. ↑ Reisner, B. A.; Stacy, A. M. (1998). "Sr
    3    ARhO
    6     (A = Li, Na): Crystallization of a Rhodium(V) Oxide from Molten Hydroxide". Journal of the American Chemical Society. 120 (37): 9682–9989. doi:10.1021/ja974231q.
  30. ↑ Griffith, W. P. (1976). The Rarer Platinum Metals. New York: John Wiley and Sons.
  31. ↑ Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  32. ↑ David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.
  33. ↑ Barbalace, Kenneth, "Table of Elements [ permanent dead link ]". Environmental Chemistry.com; retrieved 2007-04-14.
  34. ↑ D.E.Ryan, J.Holzbecher and R.R.Brooks, Chemical Geology, Volume 85, Issues 3–4, 30 July 1990, Pages 295-303
  35. ↑ Orecchio and Amorello, Foods, 2019, volume 8, issue 2, doi : 10.3390/foods8020059
  36. 1 2 Loferski, Patricia J. (2013). "Commodity Report: Platinum-Group Metals" (PDF). United States Geological Survey. Retrieved 16 July 2012.
  37. ↑ Kolarik, Zdenek; Renard, Edouard V. (2005). "Potential Applications of Fission Platinoids in Industry" (PDF). Platinum Metals Review. 49 (2): 79. doi: 10.1595/147106705X35263 .
  38. ↑ Kolarik, Zdenek; Renard, Edouard V. (2003). "Recovery of Value Fission Platinoids from Spent Nuclear Fuel. Part I PART I: General Considerations and Basic Chemistry" (PDF). Platinum Metals Review. 47 (2): 74–87. doi:10.1595/003214003X4727487.
  39. ↑ Kolarik, Zdenek; Renard, Edouard V. (2003). "Recovery of Value Fission Platinoids from Spent Nuclear Fuel. Part II: Separation Process" (PDF). Platinum Metals Review. 47 (2): 123–131. doi:10.1595/003214003X473123131.
  40. ↑ Shelef, M.; Graham, G. W. (1994). "Why Rhodium in Automotive Three-Way Catalysts?". Catalysis Reviews. 36 (3): 433–457. doi:10.1080/01614949408009468.
  41. ↑ Murray, Angela Janet (2012). Recovery of Platinum Group Metals from Spent Furnace Linings and Used Automotive Catalysts (PDF) (PhD thesis). University of Birmingham.
  42. ↑ "The Rhodium Market and Rhodium Price".
  43. ↑ Roth, James F. (1975). "Rhodium Catalysed Carbonylation of Methanol" (PDF). Platinum Metals Review. 19 (1 January): 12–14. doi:10.1595/003214075X1911214. Archived from the original (PDF) on 24 September 2015. Retrieved 5 February 2009.
  44. ↑ Hartwig, John (2010). Organotransition Metal Chemistry: From Bonding to Catalysis. New York: University Science Books. p. 1160. ISBN   978-1-938787-15-7.
  45. ↑ C. Elschenbroich (2006). Organometallics. VCH. ISBN   978-3-527-29390-2.
  46. ↑ Heidingsfeldova, M. & Capka, M. (2003). "Rhodium complexes as catalysts for hydrosilylation crosslinking of silicone rubber". Journal of Applied Polymer Science. 30 (5): 1837. doi:10.1002/app.1985.070300505.
  47. ↑ Halligudi, S. B.; et al. (1992). "Hydrogenation of benzene to cyclohexane catalyzed by rhodium(I) complex supported on montmorillonite clay". Reaction Kinetics and Catalysis Letters. 48 (2): 547. Bibcode:1992RKCL...48..505T. doi:10.1007/BF02162706. S2CID   97802315.
  48. ↑ Fischer, Torkel; Fregert, S.; Gruvberger, B.; Rystedt, I. (1984). "Contact sensitivity to nickel in white gold". Contact Dermatitis. 10 (1): 23–24. doi:10.1111/j.1600-0536.1984.tb00056.x. PMID   6705515. S2CID   46626556.
  49. ↑ "Hit & Run: Ring the changes". The Independent . London. 2 December 2008. Retrieved 6 June 2009.
  50. ↑ Lide, David R (2004). CRC handbook of chemistry and physics 2004–2005: a ready-reference book of chemical and physical data (85th ed.). Boca Raton: CRC Press. pp. 4–26. ISBN   978-0-8493-0485-9.
  51. ↑ Weisberg, Alfred M. (1999). "Rhodium plating". Metal Finishing. 97 (1): 296–299. doi:10.1016/S0026-0576(00)83088-3.
  52. ↑ Smith, Warren J. (2007). "Reflectors". Modern optical engineering: the design of optical systems. McGraw-Hill. pp. 247–248. ISBN   978-0-07-147687-4.
  53. ↑ McDonagh, C P; et al. (1984). "Optimum x-ray spectra for mammography: choice of K-edge filters for tungsten anode tubes". Phys. Med. Biol. 29 (3): 249–52. Bibcode:1984PMB....29..249M. doi:10.1088/0031-9155/29/3/004. PMID   6709704. S2CID   250873106.
  54. ↑ Sokolov, A. P.; Pochivalin, G. P.; Shipovskikh, Yu. M.; Garusov, Yu. V.; Chernikov, O. G.; Shevchenko, V. G. (1993). "Rhodium self-powered detector for monitoring neutron fluence, energy production, and isotopic composition of fuel". Atomic Energy. 74 (5): 365–367. doi:10.1007/BF00844622. S2CID   96175609.
  55. ↑ Stwertka, Albert. A Guide to the Elements, Oxford University Press, 1996, p. 125. ISBN   0-19-508083-1
  56. ↑ "MSDS - 357340". www.sigmaaldrich.com.
  57. ↑ Leikin, Jerrold B.; Paloucek Frank P. (2008). Poisoning and Toxicology Handbook. Informa Health Care. p. 846. ISBN   978-1-4200-4479-9.
  58. ↑ Landolt, Robert R.; Berk Harold W.; Russell, Henry T. (1972). "Studies on the toxicity of rhodium trichloride in rats and rabbits". Toxicology and Applied Pharmacology . 21 (4): 589–590. Bibcode:1972ToxAP..21..589L. doi:10.1016/0041-008X(72)90016-6. PMID   5047055.
  59. ↑ "NIOSH Pocket Guide to Chemical Hazards - Rhodium (metal fume and insoluble compounds, as Rh)". CDC. Retrieved 21 November 2015.
  60. ↑ "NIOSH Pocket Guide to Chemical Hazards - Rhodium (soluble compounds, as Rh)". CDC. Retrieved 21 November 2015.

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