Gd#65 / 118Dy

65Tb158.93

Lanthanides (Rare Earths)solid at STPF-block

Terbium

Group: f-block•Period: 6•Standard Atomic Weight: 158.93 u

Open Full Periodic Table View Bohr Model

Why is Terbium in this position?

Understanding the scientific rationale behind Terbium'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 valence electrons fill 4f orbitals (4f⁹ 6s²).

Chemical Category

Lanthanides (Rare Earths)

Classified as a lanthanide rare earth metal with premier magnetostrictive properties.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 8, 18, 27, 8, 2]

Bohr Atomic Shell Model(2, 8, 18, 27, 8, 2)

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

65 Protons (p⁺)94 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):27 / 32 electrons (84%)

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 4f⁹ 5s² 5p⁶ 6s²

Neutral ground state configuration. Valence electrons: 11.

Atomic & Quantum Properties

Electronegativity (Pauling)1.2 Pauling

1st Ionization Energy565.8 kJ/mol

Electron Affinity-50 kJ/mol

Atomic Radius (empirical)180 pm

Common Oxidation States+3, +4

Crystal StructureHCP

Physical & Thermal Properties

Density at STP8.23 g/cm³

Melting Point1356 °C (1629 K)

Boiling Point3230 °C (3503 K)

Magnetic OrderingFerromagnetic

Discovery Year1843

Discovered ByCarl Gustaf Mosander

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses

Terfenol-D magnetostrictive sonar transducers and precision acoustic actuators
Green phosphors for color displays and energy-saving trichromatic fluorescent lamps (Tb³⁺)
Solid-state optical isolators and Faraday rotators for high-power lasers
Fuel cell high-temperature electrolyte structural stabilizers

Occurrence in Nature

Occurs in low concentrations in bastnäsite, monazite, and ionic adsorption clay deposits.

Etymology & Name Origin

Named after the village of Ytterby, Sweden

Important Chemical Compounds

Tb₄O₇ (Terbium(III,IV) oxide)

TbCl₃ (Terbium chloride)

Terfenol-D alloy

Interesting Chemical Facts

• Terfenol-D expands and contracts vigorously when placed in a magnetic field (magnetostriction), capable of turning entire building walls into acoustic audio speakers.
• Terbium produces a razor-sharp, monochromatic lemon-green emission line at 543 nm, crucial for color television green subpixels.
• Along with yttrium, erbium, and ytterbium, terbium is one of four chemical elements named after the tiny Swedish village of Ytterby.

Safety & Handling Note

Low to moderate toxicity; terbium metal dust is flammable.