Rhenium
Rhenium (Re, atomic number 75) is a Period 6 transition metal (d-block, 186.21 u). Last stable, non-radioactive element discovered (1925) and one of the rarest elements in Earth's crust (~0.7 ppb). Added to single-crystal nickel superalloys to withst
Rhenium is a chemical element on the periodic table with the atomic symbol Re, atomic number 75, and standard atomic weight 186.21 u. Classified as a Transition Metal within Group 7 and Period 6 (d-block), rhenium possesses a ground-state electron configuration of [Xe] 4f14 5d5 6s2 distributed across 6 concentric Bohr electron shells (2 · 8 · 18 · 32 · 13 · 2) with 2 outer-shell electrons. Last stable, non-radioactive element discovered (1925) and one of the rarest elements in Earth's crust (~0.7 ppb). Added to single-crystal nickel superalloys to withstand >1,100 °C inside jet engine turbine blades.
⚛️ Interactive Periodic Table Lab: Explore Rhenium (Re, Z = 75) in the CRV Science Dynamic Periodic Table & Bohr Orbital Lab to visualize its animated 2 · 8 · 18 · 32 · 13 · 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 Rhenium?
Electron Shell Architecture and Ground-State Configuration
A neutral atom of rhenium contains 75 protons in its atomic nucleus balanced by 75 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): 13e−, P (n=6): 2e−), terminating in the four-lobed d-orbital manifold (azimuthal quantum number l = 2) with ground-state configuration [Xe] 4f14 5d5 6s2. Removing the most loosely bound valence electron from an isolated gaseous rhenium atom requires a first ionization energy of 760 kJ/mol, while its tendency to attract shared bonding electrons is quantified by a Pauling electronegativity of 1.90.
Periodic Table Position and Neighboring Elements
Within the periodic table, Rhenium occupies Period 6, Group 7 of the d-block (Transition Metals). Along Period 6, it is flanked by Tungsten (W, Z = 74) and Osmium (Os, Z = 76). Vertically within its periodic family, Rhenium shares valence orbital symmetry and homologous chemical trends with Manganese (Mn), Technetium (Tc), Bohrium (Bh). Learners can interactively compare Rhenium's orbital radii, ionization energy, and Pauling electronegativity against all neighboring elements in the Dynamic Periodic Table Lab.
Physical and Thermodynamic Properties: How Does Rhenium 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 rhenium exists as a crystalline solid. As thermal energy increases, its crystal or molecular lattice undergoes solid-to-liquid fusion at a melting point of 3,459 K (+3185.85 °C / +5766.5 °F) and transitions to the vapor phase at a normal boiling point of 5,869 K (+5595.85 °C / +10104.5 °F), spanning a liquid thermodynamic range of 2410 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 Rhenium'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 7 / Period 6 |
|---|---|---|---|
| Atomic Number & Symbol | Z = 75 (Re) | 75 nuclear protons; nuclear charge +75e | Located in Period 6, Group 7 (d-block) |
| Standard Atomic Weight | 186.21 u (g/mol) | Abundance-weighted isotopic nucleon mass | ~111 neutrons in dominant/reference mass number |
| Electron Configuration | [Xe] 4f14 5d5 6s2 | Shells: 2 · 8 · 18 · 32 · 13 · 2 (2 outer-shell e−) | Transition Metals valence orbital architecture |
| Electronegativity & Ionization | χ = 1.90; IE1 = 760 kJ/mol | Pauling bond polarity scale & first valence ionization enthalpy | Governs covalent vs. ionic bond character |
| Melting & Boiling Points | MP: 3459 K; BP: 5869 K | Cohesive lattice energy and intermolecular forces | STP (298 K) phase: SOLID (Liquid range: 2410 K) |
| Principal Oxidation States | +7, +4, -1 | Valence electron donation, sharing, or acceptance | Discovered / First Isolated: 1925 |
Chemical Reactivity, Bonding, and Oxidation States: How Does Rhenium Form Compounds?
Characteristic Oxidation States and Coordination Chemistry
As a d-block transition metal, partially filled (n−1)d orbitals lie close in energy to the outermost ns subshell, enabling variable oxidation states, d–d electronic transitions, coordination complex formation, and heterogeneous or metalloenzymatic redox catalysis. In chemical compounds, rhenium exhibits characteristic oxidation states of +7, +4, -1. 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)—rhenium 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 1925, Rhenium carries a distinct cosmological and geochemical signature. With atomic number Z = 75 beyond the iron-56 binding-energy peak, rhenium 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 Rhenium Important in Nature and Technology?
Biochemical Classification: Abiotic / Technological / Synthetic
In comparative biochemistry and systems physiology, Rhenium 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
Last stable, non-radioactive element discovered (1925) and one of the rarest elements in Earth's crust (~0.7 ppb). Added to single-crystal nickel superalloys to withstand >1,100 °C inside jet engine turbine blades. Researchers and students can further investigate Rhenium'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 Rhenium (Re)?
Rhenium (atomic number Z = 75) has the ground-state electron configuration [Xe] 4f14 5d5 6s2, distributing its 75 electrons across 6 shells as 2 · 8 · 18 · 32 · 13 · 2. Its outermost shell contains 2 electrons, placing Rhenium in Group 7, Period 6 (d-block) as a member of the Transition Metals. You can watch these 75 electrons orbit the nucleus in real time in the Dynamic Periodic Table Bohr Lab.
What phase of matter is Rhenium at room temperature, and when does it melt or boil?
At standard room temperature (298 K / 25 °C) and 1 atm pressure, Rhenium is a crystalline solid. It melts at 3,459 K (+3185.85 °C / +5766.5 °F) and boils at 5,869 K (+5595.85 °C / +10104.5 °F). Using the 0–6,000 K temperature slider in the Interactive Periodic Table, you can observe Rhenium's exact solid, liquid, and gas transitions relative to all other elements.
How does Rhenium function in biochemistry, materials science, and technology?
Last stable, non-radioactive element discovered (1925) and one of the rarest elements in Earth's crust (~0.7 ppb). Added to single-crystal nickel superalloys to withstand >1,100 °C inside jet engine turbine blades. In biological systems, it is categorized under Abiotic / Technological / Synthetic, with principal oxidation states of +7, +4, -1 and a first ionization energy of 760 kJ/mol.