Berkelium (Bk)

Silvery

Berkelium is a synthetic actinide named after Berkeley, California, where it was first produced, and with [Rn] 5f⁹ 7s², berkelium-247 (half-life 1380 years) is produced by neutron bombardment of americium in nuclear reactors. Only about 1 gram has been produced in total, used primarily to synthesize element 117 (tennessine).

Key metrics

Density14.8g/cm³

Melting point1,259K

Boiling point2,900K

Electronegativity1.3Pauling

Discovery

1949discovered

Discovered by: Lawrence Berkeley Lab
Reactivity profile: Radioactive synthetic element
Reactivity: Medium
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Rn]}\; \textcolor{#a855f7}{5_{f}^{9}}\; \textcolor{#ef4444}{7_{s}^{2}}

[Rn] 5f9 7s2

Wave function

\Psi_{\text{Bk}} \approx \frac{1}{\sqrt{97!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{97}(\mathbf{r}_{97}) \right|

Probability density $|\Psi|^2$ across the Bk 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: 170 pm
Ionization energy: 601 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

1259 K2900 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

438.0nmBk I (blue)Violet60%

495.0nmBk ICyan40%

510.0nmBk I (green)Green100%

Dominant line 510.0 nmRange 438–510 nmTransitions 3