Lutetium
Lutetium (Lu, atomic number 71) is a Period 6 lanthanide (d-block, 174.97 u). Final, heaviest, and smallest-radius lanthanide due to the cumulative lanthanide contraction. ¹⁷⁷Lu is conjugated to tumor-targeting peptides for targeted radiopharmaceutic
Lutetium is a chemical element on the periodic table with the atomic symbol Lu, atomic number 71, and standard atomic weight 174.97 u. Classified as a Lanthanide within Group 3 and Period 6 (d-block), lutetium possesses a ground-state electron configuration of [Xe] 4f14 5d1 6s2 distributed across 6 concentric Bohr electron shells (2 · 8 · 18 · 32 · 9 · 2) with 2 outer-shell electrons. Final, heaviest, and smallest-radius lanthanide due to the cumulative lanthanide contraction. ¹⁷⁷Lu is conjugated to tumor-targeting peptides for targeted radiopharmaceutical cancer therapy.
⚛️ Interactive Periodic Table Lab: Explore Lutetium (Lu, Z = 71) in the CRV Science Dynamic Periodic Table & Bohr Orbital Lab to visualize its animated 2 · 8 · 18 · 32 · 9 · 2 electron shells, simulate live phase transitions from 0 K to 6,000 K, and compare periodic heatmaps across all 118 IUPAC elements.
Atomic Structure and Periodic Trends: How Do Quantum Orbitals Define Lutetium?
Electron Shell Architecture and Ground-State Configuration
A neutral atom of lutetium contains 71 protons in its atomic nucleus balanced by 71 electrons occupying quantized atomic orbitals. In the Bohr-Sommerfeld and quantum-mechanical orbital models, these electrons populate 6 principal energy shells (K (n=1): 2e−, L (n=2): 8e−, M (n=3): 18e−, N (n=4): 32e−, O (n=5): 9e−, P (n=6): 2e−), terminating in the four-lobed d-orbital manifold (azimuthal quantum number l = 2) with ground-state configuration [Xe] 4f14 5d1 6s2. Removing the most loosely bound valence electron from an isolated gaseous lutetium atom requires a first ionization energy of 524 kJ/mol, while its tendency to attract shared bonding electrons is quantified by a Pauling electronegativity of 1.27.
Periodic Table Position and Neighboring Elements
Within the periodic table, Lutetium occupies Period 6, Group 3 of the d-block (Lanthanides). Along Period 6, it is flanked by Ytterbium (Yb, Z = 70) and Hafnium (Hf, Z = 72). Vertically within its periodic family, Lutetium shares valence orbital symmetry and homologous chemical trends with Lanthanum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd). Learners can interactively compare Lutetium's orbital radii, ionization energy, and Pauling electronegativity against all neighboring elements in the Dynamic Periodic Table Lab.
Physical and Thermodynamic Properties: How Does Lutetium Behave Across Temperature Regimes?
Standard Phase, Melting Point, and Boiling Point Dynamics
At standard ambient temperature and pressure (298.15 K / 25 °C, 1 atm), elemental lutetium exists as a crystalline solid. As thermal energy increases, its crystal or molecular lattice undergoes solid-to-liquid fusion at a melting point of 1,925 K (+1651.85 °C / +3005.3 °F) and transitions to the vapor phase at a normal boiling point of 3,675 K (+3401.85 °C / +6155.3 °F), spanning a liquid thermodynamic range of 1750 K. In the CRV Science Dynamic Periodic Table, dragging the live temperature slider between absolute zero (0 K) and solar-photosphere temperatures (6,000 K) dynamically tracks Lutetium's state transitions in real time alongside enthalpy and entropy phase equilibria.
Quantitative Atomic and Thermodynamic Parameter Matrix
| Parameter | Quantitative Value / Formula | Physical / Quantum Basis | Comparative Context in Group 3 / Period 6 |
|---|---|---|---|
| Atomic Number & Symbol | Z = 71 (Lu) | 71 nuclear protons; nuclear charge +71e | Located in Period 6, Group 3 (d-block) |
| Standard Atomic Weight | 174.97 u (g/mol) | Abundance-weighted isotopic nucleon mass | ~104 neutrons in dominant/reference mass number |
| Electron Configuration | [Xe] 4f14 5d1 6s2 | Shells: 2 · 8 · 18 · 32 · 9 · 2 (2 outer-shell e−) | Lanthanides valence orbital architecture |
| Electronegativity & Ionization | χ = 1.27; IE1 = 524 kJ/mol | Pauling bond polarity scale & first valence ionization enthalpy | Governs covalent vs. ionic bond character |
| Melting & Boiling Points | MP: 1925 K; BP: 3675 K | Cohesive lattice energy and intermolecular forces | STP (298 K) phase: SOLID (Liquid range: 1750 K) |
| Principal Oxidation States | +3 | Valence electron donation, sharing, or acceptance | Discovered / First Isolated: 1907 |
Chemical Reactivity, Bonding, and Oxidation States: How Does Lutetium Form Compounds?
Characteristic Oxidation States and Coordination Chemistry
As a 4f-block inner transition metal (rare-earth lanthanide), progressive filling of radially contracted inner 4f orbitals—shielded by outer 5s² 5p⁶ shells—produces the trivalent (+3) lanthanide contraction and sharp f–f optical and magnetic transitions. In chemical compounds, lutetium exhibits characteristic oxidation states of +3. Depending on the electronegativity difference (Δχ) of its bonding partners—such as Oxygen (χ = 3.44), Fluorine (χ = 3.98), Chlorine (χ = 3.16), Nitrogen (χ = 3.04), Carbon (χ = 2.55), or Hydrogen (χ = 2.20)—lutetium forms redox-specific oxides, halides, hydrides, or coordination complexes governed by Gibbs free energy (ΔG = ΔH − TΔS).
Nucleosynthesis, Discovery History, and Elemental Origins
First identified or isolated in 1907, Lutetium carries a distinct cosmological and geochemical signature. With atomic number Z = 71 beyond the iron-56 binding-energy peak, lutetium is synthesized astrophysically via neutron-capture nucleosynthesis—combining slow neutron capture (the s-process in asymptotic giant branch stars) and rapid neutron capture (the r-process in neutron-star mergers and core-collapse supernovae).
Biological Role and Scientific Applications: Why Is Lutetium Important in Nature and Technology?
Biochemical Classification: Abiotic / Technological / Synthetic
In comparative biochemistry and systems physiology, Lutetium is classified as Abiotic / Technological / Synthetic. No known essential biological role; important in planetary geochemistry, astrophysics, materials science, or nuclear physics. Across terrestrial and marine ecosystems, its chemical speciation interacts with thermodynamics, enthalpy, entropy, chemistry.
Key Mechanistic Functions and Technological Uses
Final, heaviest, and smallest-radius lanthanide due to the cumulative lanthanide contraction. ¹⁷⁷Lu is conjugated to tumor-targeting peptides for targeted radiopharmaceutical cancer therapy. Researchers and students can further investigate Lutetium's functional role alongside all 118 elements by launching the Interactive Periodic Table & Element Detective Lab on CRV Science Learn.
Frequently Asked Scientific Questions
What is the electron configuration and valence shell structure of Lutetium (Lu)?
Lutetium (atomic number Z = 71) has the ground-state electron configuration [Xe] 4f14 5d1 6s2, distributing its 71 electrons across 6 shells as 2 · 8 · 18 · 32 · 9 · 2. Its outermost shell contains 2 electrons, placing Lutetium in Group 3, Period 6 (d-block) as a member of the Lanthanides. You can watch these 71 electrons orbit the nucleus in real time in the Dynamic Periodic Table Bohr Lab.
What phase of matter is Lutetium at room temperature, and when does it melt or boil?
At standard room temperature (298 K / 25 °C) and 1 atm pressure, Lutetium is a crystalline solid. It melts at 1,925 K (+1651.85 °C / +3005.3 °F) and boils at 3,675 K (+3401.85 °C / +6155.3 °F). Using the 0–6,000 K temperature slider in the Interactive Periodic Table, you can observe Lutetium's exact solid, liquid, and gas transitions relative to all other elements.
How does Lutetium function in biochemistry, materials science, and technology?
Final, heaviest, and smallest-radius lanthanide due to the cumulative lanthanide contraction. ¹⁷⁷Lu is conjugated to tumor-targeting peptides for targeted radiopharmaceutical cancer therapy. In biological systems, it is categorized under Abiotic / Technological / Synthetic, with principal oxidation states of +3 and a first ionization energy of 524 kJ/mol.