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Uranium is a chemical element on the periodic table with the atomic symbol U, atomic number 92, and standard atomic weight 238.03 u. Classified as a Actinide within Group 3 and Period 7 (f-block), uranium possesses a ground-state electron configuration of [Rn] 5f³ 6d¹ 7s² distributed across 7 concentric Bohr electron shells (2 · 8 · 18 · 32 · 21 · 9 · 2) with 2 outer-shell electrons. Heaviest primordial element on Earth: ²³⁵U (0.72%) undergoes thermal-neutron nuclear fission releasing ~200 MeV per atom, while dual ²³⁸U→²⁰⁶Pb and ²³⁵U→²⁰⁷Pb Concordia dating is the gold standard of geochronology.

⚛️ Interactive Periodic Table Lab: Explore Uranium (U, Z = 92) in the CRV Science Dynamic Periodic Table & Bohr Orbital Lab to visualize its animated 2 · 8 · 18 · 32 · 21 · 9 · 2 electron shells, simulate live phase transitions from 0 K to 6,000 K, and compare periodic heatmaps across all 118 IUPAC elements.

Electron Shell Architecture and Ground-State Configuration

A neutral atom of uranium contains 92 protons in its atomic nucleus balanced by 92 electrons occupying quantized atomic orbitals. In the Bohr-Sommerfeld and quantum-mechanical orbital models, these electrons populate 7 principal energy shells (K (n=1): 2e⁻, L (n=2): 8e⁻, M (n=3): 18e⁻, N (n=4): 32e⁻, O (n=5): 21e⁻, P (n=6): 9e⁻, Q (n=7): 2e⁻), terminating in the seven-orbital f-subshell manifold (azimuthal quantum number l = 3) with ground-state configuration [Rn] 5f³ 6d¹ 7s². Removing the most loosely bound valence electron from an isolated gaseous uranium atom requires a first ionization energy of 598 kJ/mol, while its tendency to attract shared bonding electrons is quantified by a Pauling electronegativity of 1.38.

Periodic Table Position and Neighboring Elements

Within the periodic table, Uranium occupies Period 7, Group 3 of the f-block (Actinides). Along Period 7, it is flanked by Protactinium (Pa, Z = 91) and Neptunium (Np, Z = 93). Vertically within its periodic family, Uranium shares valence orbital symmetry and homologous chemical trends with Actinium (Ac), Thorium (Th), Protactinium (Pa), Neptunium (Np). Learners can interactively compare Uranium's orbital radii, ionization energy, and Pauling electronegativity against all neighboring elements in the Dynamic Periodic Table Lab.

Standard Phase, Melting Point, and Boiling Point Dynamics

At standard ambient temperature and pressure (298.15 K / 25 °C, 1 atm), elemental uranium exists as a crystalline solid. As thermal energy increases, its crystal or molecular lattice undergoes solid-to-liquid fusion at a melting point of 1,405.3 K (+1132.15 °C / +2069.9 °F) and transitions to the vapor phase at a normal boiling point of 4,404 K (+4130.85 °C / +7467.5 °F), spanning a liquid thermodynamic range of 2998.70 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 Uranium's state transitions in real time alongside enthalpy and entropy phase equilibria.

Quantitative Atomic and Thermodynamic Parameter Matrix

Characteristic Oxidation States and Coordination Chemistry

As a 5f-block actinide element with radially extended 5f, 6d, and 7s valence orbitals and an unstable heavy nucleus, it combines multi-valent actinide coordination chemistry with radioactive alpha, beta, or spontaneous-fission decay. In chemical compounds, uranium exhibits characteristic oxidation states of +6, +4. 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)—uranium 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 1789, Uranium carries a distinct cosmological and geochemical signature. With atomic number Z = 92 beyond the iron-56 binding-energy peak, uranium 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).

Biochemical Classification: Abiotic / Technological / Synthetic

In comparative biochemistry and systems physiology, Uranium 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

Heaviest primordial element on Earth: ²³⁵U (0.72%) undergoes thermal-neutron nuclear fission releasing ~200 MeV per atom, while dual ²³⁸U→²⁰⁶Pb and ²³⁵U→²⁰⁷Pb Concordia dating is the gold standard of geochronology. Researchers and students can further investigate Uranium's functional role alongside all 118 elements by launching the Interactive Periodic Table & Element Detective Lab on CRV Science Learn.

What is the electron configuration and valence shell structure of Uranium (U)?

Uranium (atomic number Z = 92) has the ground-state electron configuration [Rn] 5f³ 6d¹ 7s², distributing its 92 electrons across 7 shells as 2 · 8 · 18 · 32 · 21 · 9 · 2. Its outermost shell contains 2 electrons, placing Uranium in Group 3, Period 7 (f-block) as a member of the Actinides. You can watch these 92 electrons orbit the nucleus in real time in the Dynamic Periodic Table Bohr Lab.

What phase of matter is Uranium at room temperature, and when does it melt or boil?

At standard room temperature (298 K / 25 °C) and 1 atm pressure, Uranium is a crystalline solid. It melts at 1,405.3 K (+1132.15 °C / +2069.9 °F) and boils at 4,404 K (+4130.85 °C / +7467.5 °F). Using the 0–6,000 K temperature slider in the Interactive Periodic Table, you can observe Uranium's exact solid, liquid, and gas transitions relative to all other elements.

How does Uranium function in biochemistry, materials science, and technology?

Heaviest primordial element on Earth: ²³⁵U (0.72%) undergoes thermal-neutron nuclear fission releasing ~200 MeV per atom, while dual ²³⁸U→²⁰⁶Pb and ²³⁵U→²⁰⁷Pb Concordia dating is the gold standard of geochronology. In biological systems, it is categorized under Abiotic / Technological / Synthetic, with principal oxidation states of +6, +4 and a first ionization energy of 598 kJ/mol.