Terbium (Tb)

Silvery white

Terbium produces the green phosphor in fluorescent lights and color TV screens, and with nine electrons in the 4f shell, terbium³⁺ emits a strong green line (545 nm) at 98% of its total emission. Terfenol-D (Tb₀.₃Dy₀.₇Fe₂) is the most magnetostrictive material known, used in sonar and precision actuators.

Key metrics

Density8.23g/cm³

Melting point1,629K

Boiling point3,503K

Electronegativity1.1Pauling

Discovery

1843discovered

Discovered by: Carl Gustaf Mosander
Reactivity profile: Oxidizes in air
Reactivity: High
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Xe]}\; \textcolor{#a855f7}{4_{f}^{9}}\; \textcolor{#ef4444}{6_{s}^{2}}

[Xe] 4f9 6s2

Wave function

\Psi_{\text{Tb}} \approx \frac{1}{\sqrt{65!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{65}(\mathbf{r}_{65}) \right|

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

Crystal structure

Hexagonal Close-Packed

Lattice constantsa 1.00 · b 1.00 · c 1.63

Cell anglesα 90° · β 90° · γ 120°

Coordination number12

Atoms per cell2

Atomic packing factor0.74

Physical properties

Atomic radius: 177 pm
Ionization energy: 565 kJ/mol
Electron affinity: 50 kJ/mol
Crystal structure: Hexagonal close-packed (hcp)

Oxidation states

Acid/base

Basic

Strongly acidicStrongly basic

State at 25 °CSolid

1629 K3503 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

431.9nmTb I (blue)Violet40%

531.7nmTb I (green)Green100%

540.1nmTb IGreen70%

Dominant line 531.7 nmRange 432–540 nmTransitions 3