Curium (Cm)

Silvery metal

Curium is a hard, intensely radioactive actinide that generates enough heat to glow red in the dark, and with [Rn] 5f⁷ 6d¹ 7s², curium-244 (half-life 18.1 years) produces 2.8 W/g from alpha decay. It was the first transuranium element produced in weighable quantities and was used in the Alpha Particle X-ray Spectrometer on Mars rovers.

Key metrics

Density13.5g/cm³

Melting point1,613K

Boiling point3,383K

Electronegativity1.3Pauling

Discovery

1944discovered

Discovered by: Glenn T. Seaborg
Reactivity profile: Strongly radioactive
Reactivity: Medium
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Rn]}\; \textcolor{#a855f7}{5_{f}^{7}}\; \textcolor{#22c55e}{6_{d}^{1}}\; \textcolor{#ef4444}{7_{s}^{2}}

[Rn] 5f7 6d1 7s2

Wave function

\Psi_{\text{Cm}} \approx \frac{1}{\sqrt{96!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{96}(\mathbf{r}_{96}) \right|

Probability density $|\Psi|^2$ across the Cm valence shell.

Crystal structure

Double Hexagonal Close-Packed

Lattice constantsa 1.00 · b 1.00 · c 2.00

Cell anglesα 90° · β 90° · γ 120°

Coordination number12

Atoms per cell4

Atomic packing factor0.74

Physical properties

Atomic radius: 174 pm
Ionization energy: 581 kJ/mol
Electron affinity: 0 kJ/mol
Crystal structure: Double hexagonal close-packed

Oxidation states

+3+4

Acid/base

Basic

Strongly acidicStrongly basic

State at 25 °CSolid

1613 K3383 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

446.0nmCm I (blue)Violet60%

505.0nmCm ICyan40%

520.0nmCm I (green)Green100%

Dominant line 520.0 nmRange 446–520 nmTransitions 3