---
title: "Gadolinium (Gd) — element 64"
description: "Gadolinium is element 64, symbol Gd, atomic weight 157.25. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/gadolinium/
site: "At One Place"
---

# Gadolinium (Gd)

**Gadolinium — element 64: Gd**

157.25 u · Lanthanide · period 6

Gadolinium-157 has the largest thermal neutron capture cross-section of any stable nuclide — around 250,000 barns, roughly a quarter of a million times that of ordinary hydrogen — which makes a thin gadolinium foil an extremely effective neutron shield. It is ferromagnetic below 20 °C, so a gadolinium sample held in a cold room sticks to a magnet and stops doing so once it warms in your hand. Its seven unpaired f electrons are what make gadolinium chelates the standard MRI contrast agent; the free ion is toxic, so it is always wrapped in a cage of ligands.

## Properties

- **Atomic number:** 64
- **Symbol:** Gd
- **Standard atomic weight:** 157.25 u
- **Category:** Lanthanide
- **Period:** 6
- **Block:** f-block
- **Electron configuration:** [Xe] 6s² 4f⁷ 5d¹
- **Electrons per shell:** 2, 8, 18, 25, 9, 2
- **Melting point:** 1,586 K — 1312.8 °C — 2395.1 °F
- **Boiling point:** 3,546 K — 3272.8 °C — 5923.1 °F
- **Density:** 7.9 g/cm³
- **Electronegativity:** 1.2 (Pauling)
- **Oxidation states:** +3
- **Discovered:** 1880 by Jean Charles Galissard de Marignac

## Electron configuration

- **Full:** 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f⁷ 5d¹
- **Noble gas shorthand:** [Xe] 6s² 4f⁷ 5d¹
- **Shells:** K: 2 · L: 8 · M: 18 · N: 25 · O: 9 · P: 2

## What it is used for

- MRI contrast agents, in about a third of all scans
- Neutron shielding and reactor control rods
- Magnetic refrigeration research
- Green phosphors in X-ray intensifying screens
- Improving the workability of iron and chromium alloys

## Hazards

- Free gadolinium ions are toxic; some MRI contrast agents deposit trace gadolinium in tissue

> Anomalous electron configuration: [Xe] 6s² 4f⁷ 5d¹ rather than the predicted 6s² 4f⁸ — a half-filled f subshell is worth an electron in the d subshell. The only element named after a person via a mineral named for Johan Gadolin.

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 62 | Samarium | Sm | 150.36 |
| 63 | Europium | Eu | 151.96 |
| 64 | Gadolinium ← | Gd | 157.25 |
| 65 | Terbium | Tb | 158.93 |
| 66 | Dysprosium | Dy | 162.5 |

## Common questions

### What is the atomic number of gadolinium?

64. That is the number of protons in its nucleus, which is what defines the element.

### What is the symbol for gadolinium?

Gd.

### What is the electron configuration of gadolinium?

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f⁷ 5d¹, or [Xe] 6s² 4f⁷ 5d¹ in noble-gas shorthand.

### What is the melting point of gadolinium?

1,586 K — 1312.8 °C — 2395.1 °F

## Related pages

- [Samarium (Sm)](https://atoneplace.net/element/samarium/)
- [Europium (Eu)](https://atoneplace.net/element/europium/)
- [Terbium (Tb)](https://atoneplace.net/element/terbium/)
- [Dysprosium (Dy)](https://atoneplace.net/element/dysprosium/)

## Sources

- Official vendor product documentation — At One Place (/about/)