Gadolinium (Gd)
Gadolinium (Gd) is a lanthanide with atomic number 64 and a standard atomic weight of 157.25. At room temperature it is a solid that melts at 1,313 °C and boils at 3,273 °C.
Gadolinium key facts
Gadolinium at a glance
Identity
| Symbol | Gd |
|---|---|
| Atomic number (Z) | 64 |
| Atomic weight | 157.25 ± 0.01 (CIAAW 2024) |
| Category | Lanthanide |
| Group | — (f-block: lanthanide series) |
| Period | 6 |
| Block | f-block |
| CAS number | 7440-54-2 |
Atomic properties
| Electron configuration | [Xe] 4f7 5d1 6s2 Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f7 5s2 5p6 5d1 6s2 |
|---|---|
| Electrons per shell | 2, 8, 18, 25, 9, 2 |
| Oxidation states | +3 Less common: 0, +1, +2 |
| Electronegativity (Pauling) | 1.2 |
| First ionisation energy | 6.15 eV (593.4 kJ/mol) 2nd: 12.076 eV · 3rd: 20.54 eV |
| Atomic radius (empirical) | 180 pm |
| Covalent radius | 169 pm |
| Van der Waals radius | 234 pm |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Melting point | 1,313 °C · 2,395.4 °F · 1,586.15 K |
| Boiling point | 3,273 °C · 5,923.4 °F · 3,546.15 K |
| Density | 7.9 g/cm³ |
| Specific heat capacity | 0.236 J/(g·K) |
| Crystal structure | Hexagonal |
Isotopes & abundance
| Natural occurrence | Primordial |
|---|---|
| Radioactive | No |
| Natural isotopes (abundance) | 158Gd 24.84%, 160Gd 21.86%, 156Gd 20.47%, 157Gd 15.65%, 155Gd 14.8%, 154Gd 2.18% |
| Stable isotopes | 6 |
| Known isotopes | 40 |
| Abundance in Earth's crust | 6.2 mg/kg |
| Abundance in seawater | 0.0000007 mg/L |
Atomic weights: CIAAW Abridged Standard Atomic Weights 2024. Other properties: standard reference compilations, checked October 2026; predicted values are marked.
Gadolinium electron configuration
Gadolinium has 64 electrons. Written in short form, its ground-state configuration is [Xe] 4f7 5d1 6s2 — the electrons of the noble gas xenon, plus 4f7 5d1 6s2.Written out in full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f7 5s2 5p6 5d1 6s2.
An exception to the filling rule. The simple aufbau (Madelung) order predicts 4f8, 5d0, but gadolinium actually has 4f7, 5d1. Half-filled and filled subshells, and the close energies of the outer orbitals, make this arrangement more stable.
Discovery and name
1880 — Jean Charles Galissard de Marignac · Switzerland.
The mineral gadolinite, named after Johan Gadolin.
Known for
Gadolinium compounds are MRI contrast agents. It also absorbs neutrons strongly and is used in nuclear reactors.
Isotopes of gadolinium
Naturally occurring gadolinium is a mix of 7 isotopes. Each has 64 protons; they differ in the number of neutrons:
| Isotope | Protons | Neutrons | Natural abundance | Stability |
|---|---|---|---|---|
| 158Gd | 64 | 94 | 24.84% | stable |
| 160Gd | 64 | 96 | 21.86% | stable |
| 156Gd | 64 | 92 | 20.47% | stable |
| 157Gd | 64 | 93 | 15.65% | stable |
| 155Gd | 64 | 91 | 14.8% | stable |
| 154Gd | 64 | 90 | 2.18% | stable |
| 152Gd | 64 | 88 | 0.2% | radioactive · half-life 108 trillion years |
40 isotopes of gadolinium are known in our data set (half-lives as published in nuclear data tables).
Gadolinium and its neighbours in the lanthanide series
Neighbouring elements in the same f-block series:
| Element | Z | Atomic weight | Melting point | Boiling point | Density | Electronegativity |
|---|---|---|---|---|---|---|
| Promethium | 61 | [145] | 1,042 °C | 3,000 °C | 7.26 g/cm³ | 1.13 |
| Samarium | 62 | 150.36 | 1,072 °C | 1,794 °C | 7.52 g/cm³ | 1.17 |
| Europium | 63 | 151.96 | 822 °C | 1,529 °C | 5.24 g/cm³ | 1.2 |
| Gadolinium | 64 | 157.25 | 1,313 °C | 3,273 °C | 7.9 g/cm³ | 1.2 |
| Terbium | 65 | 158.93 | 1,359 °C | 3,230 °C | 8.23 g/cm³ | 1.1 |
| Dysprosium | 66 | 162.50 | 1,412 °C | 2,567 °C | 8.55 g/cm³ | 1.22 |
| Holmium | 67 | 164.93 | 1,472 °C | 2,700 °C | 8.8 g/cm³ | 1.23 |