ELEMENTLE

Element 45 · Transition Metal

Rhodium

Period 5 · Group 9

Rhodium 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.

Three reasons Rhodium stands out

  1. 1

    Used in catalytic converters and jewelry.

  2. 2

    It is consistently one of the most expensive metals on Earth, regularly costing more than gold.

  3. 3

    Its plating gives "white gold" jewellery its bright, durable, and highly reflective silver finish.

The rare catalyst beneath a car

Rhodium reflects light brilliantly and resists corrosion, but its greatest impact is less visible. Catalytic converters use it to reduce nitrogen oxides in exhaust. Because supply is tiny and tied to other platinum-group mining, rhodium prices can swing more dramatically than those of familiar precious metals.

Rhodium at a glance
Atomic number / protons45
SymbolRh
Family (Elementle)Transition Metal
Classification (PubChem)Transition metal
Period5
Group9
Atomic mass (u)102.9055
Standard stateSolid
Electron configuration[Kr]5s1 4d8
Reported oxidation states+3
Electronegativity (Pauling)2.28
Atomic radius (pm)195
First ionization energy (eV)7.459
Electron affinity (eV)1.137
Density (g/cm³)12.4
Melting point2237 K (1,963.85 °C)
Boiling point3968 K (3,694.85 °C)
Discovery (PubChem)1803

Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.

Sources & further reading

PubChem: Rhodium · Rhodium on Wikipedia

The introduction and original editorial story are adapted from Wikipedia contributors via Periodic-Table-JSON. Element descriptions and their adaptations are available under CC BY-SA 3.0. Numerical attributes use the PubChem periodic-table dataset, retrieved September 22, 2026.