---
title: "Dysprosium (Dy) — element 66"
description: "Dysprosium is element 66, symbol Dy, atomic weight 162.5. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/dysprosium/
site: "At One Place"
---

# Dysprosium (Dy)

**Dysprosium — element 66: Dy**

162.5 u · Lanthanide · period 6

The name means "hard to get at", which Lecoq de Boisbaudran chose after more than thirty attempts at separating it. A neodymium magnet loses strength as it heats, and an electric car motor runs hot, so a few percent of dysprosium is added to hold the coercivity — that single requirement makes dysprosium one of the most supply-critical elements in the energy transition. It also has one of the highest magnetic strengths of any element at low temperature, second only to holmium.

## Properties

- **Atomic number:** 66
- **Symbol:** Dy
- **Standard atomic weight:** 162.5 u
- **Category:** Lanthanide
- **Period:** 6
- **Block:** f-block
- **Electron configuration:** [Xe] 6s² 4f¹⁰
- **Electrons per shell:** 2, 8, 18, 28, 8, 2
- **Melting point:** 1,685 K — 1411.8 °C — 2573.3 °F
- **Boiling point:** 2,840 K — 2566.8 °C — 4652.3 °F
- **Density:** 8.55 g/cm³
- **Electronegativity:** 1.22 (Pauling)
- **Oxidation states:** +3
- **Discovered:** 1886 by Paul-Émile Lecoq de Boisbaudran

## Electron configuration

- **Full:** 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁰
- **Noble gas shorthand:** [Xe] 6s² 4f¹⁰
- **Shells:** K: 2 · L: 8 · M: 18 · N: 28 · O: 8 · P: 2

## What it is used for

- Keeping neodymium magnets working at electric-motor temperatures
- Terfenol-D actuators and sonar transducers
- Dysprosium-doped control rods in reactors
- Dosimeters, where dysprosium-doped crystals store radiation dose

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 64 | Gadolinium | Gd | 157.25 |
| 65 | Terbium | Tb | 158.93 |
| 66 | Dysprosium ← | Dy | 162.5 |
| 67 | Holmium | Ho | 164.93 |
| 68 | Erbium | Er | 167.26 |

## Common questions

### What is the atomic number of dysprosium?

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

### What is the symbol for dysprosium?

Dy.

### What is the electron configuration of dysprosium?

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁰, or [Xe] 6s² 4f¹⁰ in noble-gas shorthand.

### What is the melting point of dysprosium?

1,685 K — 1411.8 °C — 2573.3 °F

## Related pages

- [Gadolinium (Gd)](https://atoneplace.net/element/gadolinium/)
- [Terbium (Tb)](https://atoneplace.net/element/terbium/)
- [Holmium (Ho)](https://atoneplace.net/element/holmium/)
- [Erbium (Er)](https://atoneplace.net/element/erbium/)

## Sources

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