Sm#63 / 118Gd

63Eu151.96

Lanthanides (Rare Earths)solid at STPF-block

Europium

Group: f-block•Period: 6•Standard Atomic Weight: 151.96 u

Open Full Periodic Table View Bohr Model

Why is Europium in this position?

Understanding the scientific rationale behind Europium's position in the periodic table:

Group Assignment

Group Lanthanide / Actinide

Lanthanide series element filling the 4f subshell.

Period Assignment

Period 6

Belongs to Period 6 because its outermost electrons occupy n=6.

Orbital Block

F-block

Belongs to the f-block because its 4f subshell is exactly half-filled (4f⁷ 6s²), conferring special stability.

Chemical Category

Lanthanides (Rare Earths)

Classified as a lanthanide rare earth metal with hallmark luminescence.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 8, 18, 25, 8, 2]

Bohr Atomic Shell Model(2, 8, 18, 25, 8, 2)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

63 Protons (p⁺)89 Neutrons (n⁰)

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)

Shell L (n=2):8 / 8 electrons (100%)

Shell M (n=3):18 / 18 electrons (100%)

Shell N (n=4):25 / 32 electrons (78%)

Shell O (n=5):8 / 50 electrons (16%)

Shell P (n=6):2 / 72 electrons (3%)

Aufbau Electron Configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f⁷ 5s² 5p⁶ 6s²

Neutral ground state configuration. Valence electrons: 9.

Atomic & Quantum Properties

Electronegativity (Pauling)1.2 Pauling

1st Ionization Energy547.1 kJ/mol

Electron Affinity-50 kJ/mol

Atomic Radius (empirical)185 pm

Common Oxidation States+3, +2

Crystal StructureBCC

Physical & Thermal Properties

Density at STP5.24 g/cm³

Melting Point822 °C (1095 K)

Boiling Point1529 °C (1802 K)

Magnetic OrderingAntiferromagnetic

Discovery Year1901

Discovered ByEugène-Anatole Demarçay

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses

Anti-counterfeiting luminescent phosphors printed inside Euro banknotes (glow red under UV light)
Red phosphors in color television screens and trichromatic fluorescent lighting (Y₂O₂S:Eu³⁺)
Nuclear reactor control rods absorbing thermal neutrons
Biological fluorescent tagging in quantum medical assays

Occurrence in Nature

Extracted from bastnäsite and monazite ores; holds a half-filled 4f⁷ shell conferring a stable +2 divalent state.

Etymology & Name Origin

Named after the continent of Europe

Important Chemical Compounds

Eu₂O₃ (Europium oxide)

EuCl₃ (Europium chloride)

Eu(fod)₃ (NMR shift reagent)

Interesting Chemical Facts

• Every genuine Euro banknote glows with europium-doped red and blue phosphors when placed under ultraviolet blacklight.
• Europium is so soft it can be easily cut with a butter knife and reacts vigorously with water like calcium.
• The 'Europium anomaly' in geochemistry tracks whether ancient rocks crystallized under oxidizing or reducing planetary conditions.

Safety & Handling Note

Moderately toxic rare earth; pure metal is a severe fire hazard that corrodes rapidly in ambient air.