Gadolinium (Gd)

Silvery white

Gadolinium is the MRI contrast agent that makes tumors visible on medical scans, and with seven unpaired 4f electrons plus one 5d electron, Gd³⁺ has the highest magnetic moment (7.94 μB) of any ion. Gadolinium-based contrast agents (GBCAs) shorten T1 relaxation times, enhancing image contrast by 30-50%.

Key metrics

Density7.9g/cm³

Melting point1,586K

Boiling point3,546K

Electronegativity1.2Pauling

Discovery

1880discovered

Discovered by: Jean Charles Galissard de Marignac
Reactivity profile: Oxidizes slowly
Reactivity: High
Bonding: Metallic

Electron configuration

\textcolor{#6b7280}{[Xe]}\; \textcolor{#a855f7}{4_{f}^{7}}\; \textcolor{#22c55e}{5_{d}^{1}}\; \textcolor{#ef4444}{6_{s}^{2}}

[Xe] 4f7 5d1 6s2

Wave function

\Psi_{\text{Gd}} \approx \frac{1}{\sqrt{64!}} \det \left| \chi_1(\mathbf{r}_1) \dots \chi_{64}(\mathbf{r}_{64}) \right|

Probability density $|\Psi|^2$ across the Gd 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: 180 pm
Ionization energy: 593 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

1586 K3546 K298 K

Emission spectrum

3 transitions

380450500550600650700780

VioletBlueGreenYellowRed

441.5nmGd I (blue)Violet40%

553.4nmGd I (green)Green100%

572.1nmGd I (yellow)Yellow60%

Dominant line 553.4 nmRange 442–572 nmTransitions 3