LanthanideElement 63 · f-block

Europium (Eu)

Europium (Eu) is a lanthanide with atomic number 63 and a standard atomic weight of 151.96. At room temperature it is a solid that melts at 822 °C and boils at 1,529 °C.

63EuEuropium151.96

Atomic number

protons

Atomic weight

151.96

CIAAW 2024

Melting point

822 °C

1,095.15 K

Boiling point

1,529 °C

1,802.15 K

Density

5.24 g/cm³

near room temperature

Electronegativity

1.2

Pauling scale

State at 25 °C

Solid

Discovered

1896 / 1901

France

Europium at a glance

Identity

Symbol	Eu
Atomic number (Z)	63
Atomic weight	151.96 ± 0.01 (CIAAW 2024)
Category	Lanthanide
Group	— (f-block: lanthanide series)
Period	6
Block	f-block
CAS number	7440-53-1

Atomic properties

Electron configuration	[Xe] 4f⁷ 6s² Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁷ 5s² 5p⁶ 6s²
Electrons per shell	2, 8, 18, 25, 8, 2
Oxidation states	+2, +3 Less common: 0
Electronegativity (Pauling)	1.2
First ionisation energy	5.67 eV (547.1 kJ/mol) 2nd: 11.24 eV · 3rd: 24.84 eV
Electron affinity	0.864 eV
Atomic radius (empirical)	185 pm
Covalent radius	168 pm
Van der Waals radius	235 pm

Physical properties

State at 25 °C	Solid
Melting point	822 °C · 1,511.6 °F · 1,095.15 K
Boiling point	1,529 °C · 2,784.2 °F · 1,802.15 K
Density	5.24 g/cm³
Specific heat capacity	0.182 J/(g·K)
Thermal conductivity	13.9 W/(m·K)
Crystal structure	Body-centred cubic

Isotopes & abundance

Natural occurrence	Primordial
Radioactive	No
Natural isotopes (abundance)	¹⁵³Eu 52.19%, ¹⁵¹Eu 47.81% (radioactive)
Stable isotopes	2
Known isotopes	41
Abundance in Earth's crust	2 mg/kg
Abundance in seawater	0.00000013 mg/L

Atomic weights: CIAAW Abridged Standard Atomic Weights 2024. Other properties: standard reference compilations, checked October 2026; predicted values are marked.

Europium electron configuration

Europium has 63 electrons. Written in short form, its ground-state configuration is [Xe] 4f⁷ 6s² — the electrons of the noble gas xenon, plus 4f⁷ 6s².Written out in full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁷ 5s² 5p⁶ 6s².

4f↑↑↑↑↑↑↑

6s↑↓

Discovery and name

Discovered

1896 / 1901 — Eugène-Anatole Demarçay · France.

Name

Europe.

Known for

Its red and blue phosphors are used in screens and lamps, and in the anti-forgery marks on euro banknotes.

Isotopes of europium

Naturally occurring europium is a mix of 2 isotopes. Each has 63 protons; they differ in the number of neutrons:

Isotope	Protons	Neutrons	Natural abundance	Stability
¹⁵³Eu	63	90	52.19%	stable
¹⁵¹Eu	63	88	47.81%	radioactive · half-life 4.6 × 10¹⁸ years

41 isotopes of europium are known in our data set (half-lives as published in nuclear data tables).

Europium 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
Neodymium	60	144.24	1,016 °C	3,074 °C	7.01 g/cm³	1.14
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

Frequently asked questions

6 answers

What is the atomic mass of europium?

The standard atomic weight of europium is 151.96 ± 0.01 (CIAAW 2024), so one mole weighs about 151.96 grams.

How many protons, neutrons and electrons does europium have?

A neutral europium atom has 63 protons and 63 electrons. Its most common isotope, europium-153, has 90 neutrons.

What is the electron configuration of europium?

[Xe] 4f⁷ 6s² (in full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁷ 5s² 5p⁶ 6s²).

What are the melting and boiling points of europium?

Europium melts at 822 °C (1,511.6 °F) and boils at 1,529 °C (2,784.2 °F).

Is europium a metal?

Europium is a metal. It is in the f-block, period 6, and is a solid at room temperature.

Who discovered europium?

1896 / 1901 — Eugène-Anatole Demarçay (France).