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45
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76
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77
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78

 

Periodic table

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Rhodium

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Rhodium

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Rhodium

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Rodij

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Rodio

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Rodio

 

Rh
Rh
Rhodium

PERIODIC TABLE OF THE ELEMENTS

RHODIUM

TRANSITION ELEMENT:
COBALT GROUP

 

Atomic number:45

Group numbers:9

Period:5

Electronic configuration:[Kr] 4d8 5s1

Formal oxidation number:+3

Electronegativities:2.28

Atomic radius / pm:134.5

Relative atomic mass:102.90550 ± 0.00002

 

Rhodium was discovered by William Hyde Wollaston (GB) in 1804. The origin of the name comes from the Greek word rhodon meaning rose. It is a hard, silvery-white metal, inert in air and acids that reacts with fused alkalis. Rhodium is obtained as a by-product of nickel production. It is used as a coating to prevent wear on high quality science equipment and with platinum to make thermocouples.

PHYSICAL PROPERTIES

Density / g dm-3:12410 (293 K)

 10650 (m.p.)

Molar volume / cm3mol-1:8.29 (293 K)

 9.66 (m.p.)

Electrical resistivity / μΩcm:4.51 (20 °C)

THERMAL PROPERTIES

Thermal conductivity / W m-1K-1:150

Melting point / °C:1964

Boiling point / °C:3695

Heat of fusion / kJ mol-1:21.55

Heat of vaporization / kJ mol-1:494.34

Heat of atomization / kJ mol-1:555.59

IONIZATION ENERGIES

First ionization energy / kJ mol-1:719.68

Second ionization energy / kJ mol-1:1744.47

Third ionization energy / kJ mol-1:2996.86

ABUNDANCE OF ELEMENTS

in the atmosphere / ppm:-

in the Earth's crust / ppm:0.005

in the oceans / ppm:1E-10

CRYSTALLOGRAPHIC DATA

face-centered cubic

Crystal structure:

face-centered cubic

Unit-cell dimensions / pm:

a=380.36

Space group:

Fm3m

ISOTOPES

IsotopeRelative atomic massMass percent (%)
103Rh102.905504(3)100

REDUCTION POTENTIALS

Balanced half-reaction Eo / V
Rh3+ + 3e- = Rh(s)+0.8
RhCl63- + 3e- = Rh(s) + 6Cl-+0.44
Rh2O3(s) + 6H+ + 6e- = 2Rh(s) + 3H2O+0.87
RhO2 + 4H+ + 6Cl- + e- = RhCl63- + 2H2O+1.4
RhO2+ + 2H+ + e- = Rh3+ + H2O+1.40
RhO42- + 6H+ + 2e- = RhO2+ + 3H2O+1.46

 

44 Ruthenium <=
45 Rhodium
=> 46 Palladium