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Rhodium (Rh)

Rhodium is a chemical element of the periodic table with chemical symbol Rh and atomic number 45 with an atomic weight of 102.906 u and is classed as transition metal and is part of group 9 (cobalt group). Rhodium is solid at room temperature.

Rhodium in the periodic table

Atomic number45
Group9 (Cobalt group)
ClassificationTransition Metal
AppearanceSilvery white metallic
Color Silver
Number of protons45 p+
Number of neutrons58 n0
Number of electrons45 e-
From Wikipedia, the free encyclopediaRhodium is a chemical element with symbol Rh and atomic number 45. It is a rare, silvery-white, hard, and chemically inert transition metal. It is a member of the platinum group.

Physical properties

Phase at STPSolid
Density12.41 g/cm3
Atomic weight102.906 u

Thermal properties

Melting point2237 K
1963.85 °C
3566.93 °F
Boiling point3968 K
3694.85 °C
6682.73 °F
Heat of vaporization495.39 kJ/mol

Atomic properties

Electronegativity (Pauling Scale)2.28
Electron affinity110.27 kJ/mol
Oxidation states−3, −1, 0, +1, +2, +3, +4, +5, +6
(an amphoteric oxide)
Ionization energies
  1. 719.7 kJ/mol
  2. 1740 kJ/mol
  3. 2997 kJ/mol

Electron configuration for rhodium

Electron configuration
Shorthand configuration
[Kr] 4d8 5s1
Electron configuration
Full configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d8 5s1
Electron configuration chart
Electrons per shell2, 8, 18, 16, 1
Valence electrons 9
Valency electrons 3
Bohr model
RhodiumElectron shell for Rhodium, created by Injosoft ABRh
Figure: Shell diagram of Rhodium (Rh) atom.
Orbital Diagram

The history of Rhodium

Discovery and first isolationWilliam Hyde Wollaston (1804)
Discovery of rhodium
Rhodium is found in platinum or nickel ores with the other members of the platinum group metals. Rhodium (Greek rhodon (ῥόδον) meaning "rose") was discovered in 1803 by William Hyde Wollaston, soon after he discovered palladium. Rodium is named for the rose color of one of its chlorine compounds.


List of unique identifiers for Rhodium in various chemical registry databases
CAS Number7440-16-6
ChemSpider ID22389
EC number231-125-0
PubChem CID Number23948