Dysprosium (Dy)

Dysprosium is a lanthanide with atomic number 66, in period 6, in the f-block of the periodic table. Its atomic mass is 162.5 u and its electron configuration is [Xe] 4f¹⁰ 6s². Solid at 25 °C.

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Key facts

Atomic number	66
Atomic mass	162.5 u
Category	Lanthanide
Period	6
Group	f-block, no group number
Block	f
Electron configuration	[Xe] 4f¹⁰ 6s²
Electrons per shell	2, 8, 18, 28, 8, 2
Electronegativity (Pauling)	1.22
Oxidation states	+2, +3, +4common in bold
State at 25 °C	Solid
Melting point	1685 K1411.85 °C
Boiling point	2840 K2566.85 °C
Density	8.551 g/cm³

Atomic properties

First ionization energy	5.939 eV
Electron affinity	50 kJ/mol
Atomic radius	180 pm
Covalent radius	192 pm
Van der Waals radius	229 pm
Common ions	Dy³⁺
Protons, neutrons, electrons	66, 96, 66

Physical and thermal properties

Molar volume	19.01 cm³/mol
Heat of fusion	11.1 kJ/mol
Heat of vaporization	280 kJ/mol
Specific heat	167 J/(kg·K)
Thermal conductivity	11 W/(m·K)
Thermal expansion	1 × 10⁻⁵ K⁻¹
Mohs hardness	1.8
Young’s modulus	61 GPa
Crystal structure	Simple hexagonal
Magnetic type	Paramagnetic

Identification and history

CAS number	7429-91-6
Latin name	Dysprosium
Discovered by	Lecoq de Boisbaudran · 1886
Named by	---

Natural isotopes

Isotope	Mass (u)	Abundance
¹⁵⁶Dy	155.924284	0.056 %
¹⁵⁸Dy	157.924415	0.095 %
¹⁶⁰Dy	159.925204	2.329 %
¹⁶¹Dy	160.926939	18.889 %
¹⁶²Dy	161.926805	25.475 %
¹⁶³Dy	162.928737	24.896 %
¹⁶⁴Dy	163.929181	28.26 %

Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.

A dash (---) means there is no reliable published measurement. The app never makes one up.

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