Rhodium

Rhodium - Rh

CAS: 7440-16-6
Description: Silvery-white metal
Classification: Transition Metal
Date of Discovery: 1803-4
Discoverer: William Wollaston
Name Origin: Greek rhodon, "rose"

Atomic Number: 45
Number of Neutrons: 58
Atomic Mass: 102.90550(3) amu
Melting Point: 1964 ± 3 °C
Boiling Point: 3695 ± 100 °C
Density (293 K): 12.41 g/cm³
Atomic volume: 8.3 cm³/mol
Electrical resistivity: 221.729 1/mohm-cm
Thermal conductivity: 150 J/m-sec-deg
Enthalpy of atomization: 556.5 kJ/mol (est.)
Enthalpy of vaporization: 493.0 kJ/mol
Enthalpy of fusion: 21.50 kJ/mol
Specific heat capacity: 0.242 J/gK

Energy levels: 2-8-18-16-1
Electron configuration: [Kr]4d⁸5s¹
Crystal Structure: Cubic face-centered
Atomic radius: 1.34 Å
Covalent radius: 1.25 Å
Oxidation States: +2, +3, +4, +5, and +6
Electronegativity, Pauling: 2.28
Electron affinity: 1.137 eV
First ionization energy: 719.8 kJ/mol
2nd ionization energy: 1744.4 kJ/mol
3rd ionization energy: 2996.8 kJ/mol
Polarizability: 8.6 10^-24cm³

Isotope	Natural Abundance	Atomic Mass	Half-life	Decay Mode	Spin
⁹⁰Rh
⁹¹Rh
⁹²Rh	91.9320	⁺
⁹³Rh	92.9257	⁺
^94mRh	25.8 s	⁺	8+-
⁹⁴Rh	93.9217	1.18 m	⁺	3+
^95mRh	1.96 m	IT; ⁺, EC	1/2 +
⁹⁵Rh	94.9159	5.0 m	⁺	9/2+
^96mRh	1.51 m	IT; ⁺, EC	2+
⁹⁶Rh	95.91452	9.6 m	⁺; EC	5+
^97mRh	46 m	IT; ⁺, EC	1/2-
⁹⁷Rh	96.91134	31.0 m	⁺	9/2+
^98mRh	3.5 m	⁺	5+
⁹⁸Rh	97.91072	8.7 m	⁺	2+
^99mRh	4.7 h	⁺; EC	9/2+
⁹⁹Rh	98.90820	16 d	⁺; EC	1/2-
^100mRh	4.7 m	IT; ⁺	5+
¹⁰⁰Rh	99.90812	20.8 h	⁺; EC	1-
^101mRh	4.35 d	EC; IT	9/2+
¹⁰¹Rh	100.90616	3.3 y	EC	1/2-
^102mRh	207 d	IT; ^-; ⁺; EC
¹⁰²Rh	101.906842	2.9 y	EC	6+
^103mRh	56.2 m	IT	7/2+
¹⁰³Rh	100.	102.905504	Stable	1/2-
^104mRh	4.36 m	IT; ^-	5+
¹⁰⁴Rh	103.906655	42.3 s	^-; EC	1+
^105mRh	40 s	IT	1/2-
¹⁰⁵Rh	104.905692	35.4 h	^-	7/2+
^106mRh	2.18 h	^-	6+
¹⁰⁶Rh	105.90729	29.9 s	^-	1+
¹⁰⁷Rh	106.90675	21.7 m	^-	7/2+
^108mRh	6.0 m	^-
¹⁰⁸Rh	107.9087	17 s	^-	1+
¹⁰⁹Rh	108.90874	1.34 m	^-	7/2+
^110mRh	29 s	^-
¹¹⁰Rh	109.9110	3.1 s	^-	1+
¹¹¹Rh	110.9117	11 s	^-
^112mRh	6.8 s	^-
¹¹²Rh	111.9140	4 s	^-	1+
¹¹³Rh	112.9154	0.9 s	^-
^114mRh	1.8 s	^-
¹¹⁴Rh	113.9173	1.8 s	^-	1+
¹¹⁵Rh	114.9201	0.99 s	^-
^116mRh	0.9 s	^-
¹¹⁶Rh	115.9228	0.7 s	^-	1+
¹¹⁷Rh	116.925	0.44 s	^-
Wollaston discovered rhodium in 1803-4 in crude platinum ore he presumably obtained from South America. Rhodium occurs native with other platinum metals in river sands of the Urals and in North and South America. It is also found with other platinum metals in the copper-nickel sulfide ores of the Sudbury, Ontario region. Although the quantity occurring here is very small, the large tonnages of nickel processed make the recovery commercially feasible. The annual world production of rhodium is only 7 or 8 tons. The metal is silvery white and at red heat slowly changes in air to the sesquioxide. At higher temperatures it converts back to the element. Rhodium has a higher melting point and lower density than platinum. Its major use is as an alloying agent to harden platinum and palladium. Such alloys are used for furnace windings, thermocouple elements, bushings for glass fiber production, electrodes for aircraft spark plugs, and laboratory crucibles. It is useful as an electrical contact material as it has a low electrical resistance, a low and stable contact resistance, and is highly resistant to corrosion. Plated rhodium, produced by electroplating or evaporation, is exceptionally hard and is used for optical instruments. It has a high reflectance and is hard and durable. Rhodium is also used for jewelry, for decoration, and as a catalyst. Forty-four isotopes and isomers are now known. Soluble salts should not exceed 0.01 mg/m³. LINKS: DNA Recognition by Peptide Complexes of Rhodium(III) Rhodium allenylidenes Rhodium: Information, data sheet and standard forms of. Rhodium Plating Return Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998.

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