Rh
Rhodium
Element 45 · Transition metal
Rhodium (Rh)
Rhodium is a rare, silvery-white, highly reflective platinum-group metal and often the most expensive precious metal.
- Transition metal
- Period 5
- Group 9
- d-block
- solid at room temperature
Key properties
- Atomic mass
- 102.9055
- u
- Electron configuration
- [Kr] 4d8 5s1
- Melting point
- 1,963.9 °C
- 2,237 K
- Boiling point
- 3,694.9 °C
- 3,968 K
- Density
- 12.4 g/cm³
- Electronegativity
- 2.28
- Pauling
- Atomic radius
- 195 pm
- van der Waals
- 1st ionisation energy
- 7.459 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about rhodium
- 01
Most rhodium goes into catalytic converters that clean car exhaust.
- 02
White gold jewellery is often plated with rhodium for extra shine.
- 03
Its price has swung more than tenfold within a few years.
Applications
What is rhodium used for?
- Catalytic converters
- Jewellery plating
- Mirrors and searchlights
- Thermocouples
History
Discovery & name origin
Discovered by
Year
Where
England
Name origin
Greek rhodon, “rose”, for the rose-coloured salts.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 45
- Atomic mass
- 102.9055 u
- Group
- 9
- Period
- 5
- Block
- d-block
- Electron configuration
- [Kr] 4d8 5s1
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d8
- Electrons per shell
- 2, 8, 18, 16, 1
- Electronegativity (Pauling)
- 2.28
- Electron affinity
- 1.137 eV
- Atomic radius (van der Waals)
- 195 pm
- Stable isotopes
- 1
Oxidation states
Highlighted: common oxidation states (+3).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st719.7
- 2nd1,740
- 3rd2,997
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 2,237 K · 1,963.9 °C · 3,566.9 °F
- Boiling point
- 3,968 K · 3,694.9 °C · 6,682.7 °F
- Density
- 12.4 g/cm³
- Molar heat capacity
- 24.98 J/(mol·K)
- Appearance
- Silvery white metallic
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Rhodium questions
What is Rh on the periodic table?
Rh is the symbol for rhodium, element 45 on the periodic table. It sits in group 9, period 5, in the transition metal category, and has an atomic mass of 102.9055.
What is the atomic number of rhodium?
Rhodium has atomic number 45, so every rhodium atom has 45 protons in its nucleus. Its symbol is Rh and its atomic mass is 102.9055.
Who discovered rhodium?
Rhodium was discovered by William Hyde Wollaston in 1803 (England). The name comes from Greek rhodon, “rose”, for the rose-coloured salts.
What is rhodium used for?
Rhodium is used for: catalytic converters; jewellery plating; mirrors and searchlights; thermocouples.
Is rhodium a metal?
Yes. Rhodium is a transition metal, one of the metallic elements.
What is the electron configuration of rhodium?
The electron configuration of rhodium is [Kr] 4d8 5s1. Its 45 electrons are arranged in shells as 2, 8, 18, 16, 1.