Gadolinium
Definition and meaning of Gadolinium in chemistry.
Gadolinium is a chemical element with the symbol Gd and atomic number 64. It is a silvery-white rare earth metal that belongs to the lanthanide series. The element is malleable, ductile, and oxidizes slowly in dry air but tarnishes quickly in moist environments.
In more detail
Gadolinium is a heavy metal found in nature combined in minerals like monazite and bastnasite, typically extracted via ion exchange and solvent extraction techniques. It exhibits unusual magnetic properties, being strongly ferromagnetic at temperatures below 20 degrees Celsius. Above this Curie point, it becomes strongly paramagnetic, which makes its compounds highly effective as contrast agents in magnetic resonance imaging (MRI). Positioned in the f-block of the periodic table, it possesses a half-filled 4f electron subshell that contributes to its exceptional magnetic moment and high thermal neutron capture cross-section. Chemically, it reacts with hot water to form gadolinium hydroxide and dissolves readily in dilute acids. It forms colorless salts, mostly in the +3 oxidation state, which are used in specialized glasses and phosphors.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Gd |
| Atomic number | 64 |
| Atomic mass | 157.25 u |
| Category | Lanthanide |
| State at room temperature | Solid |
| Melting point | 1312 °C |
| Year discovered | 1880 |
Gadolinium(III) chelates are widely injected into patients as intravenous contrast agents to enhance the visibility of internal structures during MRI scans.
Frequently asked questions
Is gadolinium toxic?
Free gadolinium ions are highly toxic, which is why it is bound in stable chelate complexes when used for medical imaging to ensure it is excreted safely.
How does gadolinium affect MRI scans?
Its highly paramagnetic nature shortens the T1 relaxation time of water protons in tissues, leading to brighter images on T1-weighted scans.