Gadolinium
Element 64 · Lanthanide
Gadolinium is a silvery-white metal that is magnetic below room temperature and, like its neighbors, is almost always +3 in compounds. Its claim to fame is nuclear: no known element captures thermal neutrons more greedily, so gadolinium compounds are used to control reaction rates in reactors and to shield neutron instruments.
In hospitals, gadolinium-based contrast agents make MRI images dramatically clearer by changing how nearby water molecules respond to magnetic fields. Researchers also exploit its magnetocaloric effect — it heats up and cools down in changing magnetic fields — for experimental refrigeration without compressors.
Key facts
| Atomic number | 64 |
|---|---|
| Atomic weight | 157.25 |
| Category | Lanthanide |
| Group / Period | — / 6 |
| Block | f |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f7 5d1 |
| Common oxidation states | +3 |
| State at STP | Solid |
| Electronegativity | 1.20 |
| Density | 7.90 g/cm³ |
| Melting point | 1313 °C |
| Boiling point | 3273 °C |
Occurrence
Gadolinium is found in monazite, bastnasite, and gadolinite — the mineral it is named after, honoring chemist Johan Gadolin.
Applications
MRI contrast agents
Neutron capture in nuclear reactors
Magnetocaloric refrigeration research
Phosphors and scintillators
Common compounds
- gadolinium oxide
- gadolinium chloride
- gadolinium gallium garnet
Gadolinium has the highest thermal neutron capture cross-section of any known element, making it invaluable for controlling nuclear reactions.
Data source: IUPAC standard atomic weights 2021