Rhodium

General:

Name:Rhodium Symbol:Rh
Type:Transition Metal Atomic weight:102.9055
Density @ 293 K:12.4 g/cm3 Atomic volume:8.3 cm3/mol
Discovered:

Rhodium was discovered by William Hyde Wollaston in 1803 in crude platinum ore. Wollaston removed platinum and palladium from the ore to leave a red salt - sodium rhodium chloride [RhCl6]Na3.12H2O from which he extracted rhodium metal. The element name comes from the Greek word 'rhodon', meaning rose.

States

State (s, l, g):solid
Melting point:2236 K (1963 °C) Boiling point:3968 K (3695 °C)

Energies

Specific heat capacity:0.242 J g-1 K-1 Heat of atomization: 556 kJ mol-1
Heat of fusion:21.50 kJ mol-1 Heat of vaporization : 493.0 kJ mol-1
1st ionization energy:719.8 kJ mol-1 2nd ionization energy:1744.4 kJ mol-1
3rd ionization energy:2996.8 kJ mol-1 Electron affinity:109.7 kJ mol-1

Oxidation & Electrons

Shells:2,8,18,16,1 Electron configuration:[Kr] 4d8 5s1
Minimum oxidation number:-1 Maximum oxidation number:6
Min. common oxidation no.:0 Max. common oxidation no.:3
Electronegativity (Pauling Scale):2.28 Polarizability volume:8.6 Å3

Appearance & Characteristics

Structure: fcc: face-centered cubic Color:silvery-white
Hardness: 6.0 mohs
Harmful effects:

Rhodium is considered to be non-toxic. Some of its compounds are highly toxic and carcinogenic.

Characteristics:

Rhodium is a rare, hard, silvery-white, lustrous metal . It is highly reflective and extremely resistant to corrosion. It is not attacked by most acids. Rhodium's salts form rose-colored aqueous solutions.


Uses:

The majority of rhodium is used as a catalyst in catalytic converters. It is also used to catalyze industrial processes. Rhodium is used as an alloying agent for hardening and improving the corrosion resistance of platinum and palladium. As a result of its low electrical resistance, low and stable contact resistance, and its stability against corrosion rhodium is used as an electrical contact material. The metal is used in jewelry and for decorations.

Reactions

Reaction with air:mild, w/ht, ⇒ Rh2O3 Reaction with 6 M HCl:none
Reaction with 15 M HNO3:none Reaction with 6 M NaOH:

Compounds

Oxide(s):RhO2, Rh2O3 Chloride(s):RhCl3
Hydride(s):none

Radius

Atomic radius:134 pm Ionic radius (1+ ion):pm
Ionic radius (2+ ion):pm Ionic radius (3+ ion):80.5 pm
Ionic radius (2- ion):pm Ionic radius (1- ion):pm

Conductivity

Thermal conductivity:150 W m-1 K-1 Electrical conductivity:23 x 106 S m-1

Abundance & Isotopes

Abundance earth's crust:1 part per billion by weight, 0.1 parts per billion by moles
Abundance solar system:2 parts per billion by weight, 0.02 parts per billion by moles
Cost, pure:$13,000 per 100g per 100g
Cost, bulk:$7,000 per 100g
Source:

Rhodium occurs in small quantities in ores metals such as platinum, palladium, nickel, silver, and gold. Commercially, it is obtained as a byproduct of refining nickel sulfide ores from Canada.

Isotopes:

Rhodium has 24 isotopes whose half-lives are known, with mass numbers from 94 to 117. Of these, only one is stable, 103Rh.

Other

Other: