ELEMENTLE

Element 96 · Actinide

Curium

Period 7

Curium is a transuranic radioactive chemical element with symbol Cm and atomic number 96. This element of the actinide series was named after Marie and Pierre Curie – both were known for their research on radioactivity. Curium was first intentionally produced and identified in July 1944 by the group of Glenn T. Seaborg at the University of California, Berkeley.

Three reasons Curium stands out

  1. 1

    Synthetic element, named after famous polish-french female chemist.

  2. 2

    It is so intensely radioactive that a visible sample glows red in the dark from its own heat.

  3. 3

    It has been used as a power source in X-ray spectrometers on Mars rovers to analyse the composition of rocks.

An element named for two scientific lives

Curium honors Marie and Pierre Curie, whose work transformed the study of radioactivity. It is made by bombarding lighter actinides with neutrons or charged particles and generates substantial heat as it decays. Curium sources have helped instruments on Mars analyze rocks by X-ray spectroscopy.

Curium at a glance
Atomic number / protons96
SymbolCm
Family (Elementle)Actinide
Classification (PubChem)Actinide
Period7
GroupLanthanide / actinide series
Atomic mass (u)247.07035
Standard stateSolid
Electron configuration[Rn]7s2 5f7 6d1
Reported oxidation states+3
Electronegativity (Pauling)1.3
Atomic radius (pm)245
First ionization energy (eV)6.02
Electron affinity (eV)Not available
Density (g/cm³)13.51
Melting point1618 K (1,344.85 °C)
Boiling point3400 K (3,126.85 °C)
Discovery (PubChem)1944

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: Curium · Curium 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.