Europium
Atomic Data
| Atomic Number | 63 |
| Symbol | Eu |
| Atomic Weight | 151.96 u |
| Density (STP) | 5.244 g/cm³ |
| Melting Point | 825.85 °C (1099 K) |
| Boiling Point | 1528.85 °C (1802 K) |
| Electronegativity | 1.2 (Pauling) |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f7 5s2 5p6 6s2 |
| Oxidation States | +2, +3 |
| Phase at STP | Solid |
| Category | Lanthanoid |
| Period / Group | 6 / None |
| CAS Number | 7440-53-1 |
Electron Configuration
[Xe] 4f7 6s2
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 10 | 28 |
| N | 4 | 4s | 2 | 30 |
| N | 4 | 4p | 6 | 36 |
| N | 4 | 4d | 10 | 46 |
| N | 4 | 4f | 7 | 53 |
| O | 5 | 5s | 2 | 55 |
| O | 5 | 5p | 6 | 61 |
| P | 6 | 6s | 2 | 63 |
| Total | 63 | 63 | ||
Isotopes of Europium
Europium has two naturally occurring stable isotopes. The most abundant is ¹⁵³Eu, comprising 52.19% of all naturally occurring Europium.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Europium-151 | ¹⁵¹Eu | 63 | 88 | 47.81 | Stable |
| Europium-153 | ¹⁵³Eu | 63 | 90 | 52.19 | Stable |
Abundance & Occurrence
Europium is present in Earth's crust at approximately 2.1 ppm by mass and at approximately 0.05 ppm by mass throughout the universe.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Read more about the discovery of the periodic table of elements →
Safety & Handling
- Dust inhalation: Europium metal dust and europium oxide powder are respiratory and mucous membrane irritants; fine particulates should not be inhaled: use respiratory protection when handling powders.
- Fire hazard: Europium metal ignites readily in air; fine powder is pyrophoric: handle under inert gas and extinguish metal fires with dry sand or Class D agents only.
- Europium compounds: Soluble europium salts (EuCl3, Eu(NO3)3) are mild irritants to skin and eyes; wear gloves and eye protection when handling solutions.
- General toxicity: Europium has low acute systemic toxicity in its common forms; it is not known to be carcinogenic, mutagenic, or a reproductive toxicant at occupationally relevant doses.
Europium in the Real World
Real-World Uses
- Red phosphors in fluorescent lamps and LEDs: Europium(III)-activated yttrium vanadate and yttrium oxide are the standard red-emitting phosphors in tri-colour fluorescent lamps and early LED displays, providing the red primary colour needed for white light with good colour rendering.
- Euro banknote anti-counterfeiting: Europium-containing fluorescent compounds are incorporated into euro banknote paper; they glow red under UV illumination to authenticate notes, exploiting the intense, sharp Eu³ emission lines that are difficult to replicate.
- Blue phosphors and glow-in-the-dark materials: Europium(II)-doped strontium aluminate (SrAl₂O₄:Eu) is the active material in long-lasting phosphorescent glow-in-the-dark paints, safety signs, and watch dials.
- Colour TV CRT phosphors (historical): Europium-activated phosphors were responsible for the red primary in the tricolour phosphor screens of colour CRT television sets from the 1960s until the transition to flat-panel displays.
- NMR shift reagents: Europium(III) complexes are used as shift reagents in nuclear magnetic resonance (NMR) spectroscopy to spread overlapping signals in complex organic molecules, aiding structural analysis.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
What is europium used for?
Europium is the most important rare-earth phosphor activator. Europium(III) produces the red emission in fluorescent lamps and CRT televisions, while europium(II) produces blue emissions in certain phosphors. White LEDs use europium-doped phosphors to convert blue LED light to white light. Europium is also incorporated into euro banknotes as a security fluorescent marker visible under ultraviolet light.
Is europium the rarest rare earth?
Europium is one of the least abundant rare-earth elements in Earth's crust, at about 2 parts per million. While not the rarest element overall, it is among the rarest of the lanthanides and has no significant primary mineral deposits: it is extracted as a byproduct from monazite and bastnäsite processing. Its critical role in display phosphors and energy-efficient lighting makes it strategically important despite limited supply.
How was europium discovered?
Europium was discovered in 1901 by French chemist Eugène-Anatole Demarçay. He had been examining samarium-gadolinium concentrates and noticed spectral lines that did not match any known element. After careful fractionation he isolated the new element and named it after Europe, the continent where he worked. It was the first rare-earth element named after a geographic region.
How is europium used in banknote security?
Euro banknotes contain europium-doped fluorescent compounds that glow red under ultraviolet light. This is one of several anti-counterfeiting measures built into the notes. Europium's sharp, characteristic red emission at around 615 nm under UV excitation is difficult to replicate with common fluorescent dyes available to counterfeiters. Central banks routinely use UV scanners to verify banknotes.