Gadolinium
Atomic Data
| Atomic Number | 64 |
| Symbol | Gd |
| Atomic Weight | 157.25 u |
| Density (STP) | 7.9 g/cm³ |
| Melting Point | 1311.85 °C (1585 K) |
| Boiling Point | 3272.85 °C (3546 K) |
| Electronegativity | 1.2 (Pauling) |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f7 5s2 5p6 5d1 6s2 |
| Oxidation States | +3 |
| Phase at STP | Solid |
| Category | Lanthanoid |
| Period / Group | 6 / None |
| CAS Number | 7440-54-2 |
Electron Configuration
[Xe] 4f7 5d1 6s2
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 10 | 28 |
| N | 4 | 4s | 2 | 30 |
| N | 4 | 4p | 6 | 36 |
| N | 4 | 4d | 10 | 46 |
| N | 4 | 4f | 7 | 53 |
| O | 5 | 5s | 2 | 55 |
| O | 5 | 5p | 6 | 61 |
| O | 5 | 5d | 1 | 62 |
| P | 6 | 6s | 2 | 64 |
| Total | 64 | 64 | ||
Isotopes of Gadolinium
Gadolinium has six naturally occurring stable isotopes. The most abundant is ¹⁵⁸Gd, comprising 24.84% of all naturally occurring Gadolinium.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Gadolinium-154 | ¹⁵⁴Gd | 64 | 90 | 2.18 | Stable |
| Gadolinium-155 | ¹⁵⁵Gd | 64 | 91 | 14.8 | Stable |
| Gadolinium-156 | ¹⁵⁶Gd | 64 | 92 | 20.47 | Stable |
| Gadolinium-157 | ¹⁵⁷Gd | 64 | 93 | 15.65 | Stable |
| Gadolinium-158 | ¹⁵⁸Gd | 64 | 94 | 24.84 | Stable |
| Gadolinium-160 | ¹⁶⁰Gd | 64 | 96 | 21.86 | Stable |
Abundance & Occurrence
Gadolinium is present in Earth's crust at approximately 6.2 ppm by mass and at approximately 0.2 ppm by mass throughout the universe.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Read more about the discovery of the periodic table of elements →
Safety & Handling
- Gadolinium-based contrast agents (GBCAs): Gadolinium contrast agents used in MRI are associated with nephrogenic systemic fibrosis (NSF) in patients with severe renal impairment; always assess renal function before MRI contrast administration.
- Gadolinium retention: Small amounts of gadolinium are retained in the brain and other tissues after repeated GBCA exposure; the clinical significance is under investigation, but linear GBCAs are restricted or withdrawn in some jurisdictions.
- Dust inhalation: Gadolinium metal dust and oxide are respiratory irritants; use respiratory protection and ventilation when handling powders in manufacturing or research settings.
- Fire hazard: Gadolinium metal powder is flammable; metal fires require Class D agents.
Gadolinium in the Real World
Real-World Uses
- MRI contrast agents: Gadolinium chelates (Gd-DTPA, Gd-DOTA, and related complexes) are injected intravenously to enhance soft-tissue contrast in MRI scans; Gd³ shortens the T1 relaxation time of nearby water protons, brightening enhancing tissues such as tumours, inflammation, and blood vessels.
- X-ray intensifying screens: Gadolinium oxysulfide (Gd₂O₂S:Tb) is the phosphor in X-ray intensifying screens and computed radiography plates; it converts X-ray photons to visible light that exposes the photographic film or photostimulable phosphor plate with high efficiency.
- Neutron shielding in nuclear reactors: Gadolinium(III) oxide is added as a burnable poison to uranium fuel pellets to suppress excess reactivity at the beginning of fuel life; it is consumed by neutron absorption as the core operates, providing natural reactivity compensation.
- Magnetic refrigeration: Gadolinium undergoes a large magnetocaloric effect near room temperature; Gd-based alloys and compounds are the working medium in prototype magnetic refrigerators that cool without greenhouse-gas refrigerants.
- Neutron capture cancer therapy (research): Gadolinium-157, which has the highest thermal neutron capture cross-section of any stable nuclide, is being investigated for boron-neutron capture therapy (BNCT) analogues where Gd-loaded tumour-targeting compounds are irradiated to locally destroy cancer cells.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
What is gadolinium used for?
Gadolinium's most important medical use is as an MRI contrast agent: gadolinium-based contrast agents (GBCAs) are injected intravenously to enhance MRI image clarity, particularly for brain tumours, blood vessels, and inflammatory lesions. Gadolinium is also used in neutron radiography (it has an exceptionally high neutron-capture cross-section) and in gadolinium garnet crystals for microwave components.
Is gadolinium safe as an MRI contrast agent?
Gadolinium-based contrast agents (GBCAs) are generally safe in patients with normal kidney function. In patients with severe renal impairment, some older GBCAs could cause a rare but serious condition called nephrogenic systemic fibrosis (NSF), which is why GBCAs are used cautiously in such patients. More recently, studies have detected gadolinium retention in the brain and other tissues after repeated GBCA administration, though clinical significance remains under investigation.
How was gadolinium discovered?
Gadolinium was discovered in 1880 by Swiss chemist Jean Charles Galissard de Marignac, who separated it from didymia (the mixture of rare-earth oxides). He detected new spectral lines suggesting a new element. In 1886, Paul Emile Lecoq de Boisbaudran isolated it more completely. It was named after Johan Gadolin, the Finnish chemist who first identified yttria from the Ytterby quarry minerals.
Why does gadolinium have such an extreme neutron-capture cross-section?
Natural gadolinium has the highest thermal neutron-capture cross-section of any element: about 49,000 barns: primarily due to two isotopes: Gd-155 and Gd-157, which have extraordinarily high cross-sections of 61,000 and 254,000 barns respectively. This arises from resonance absorption phenomena in their nuclear structure. This extreme property makes gadolinium useful in neutron radiography, as a burnable neutron absorber in reactor fuel rods, and in boron-neutron-capture alternatives for cancer therapy.