Uranium connects minerals to nuclear-energy systems. Different uranium isotopes play different roles: uranium-235 can sustain a fission chain reaction, while neutron capture and subsequent decay can transform uranium-238 into plutonium. Identifying the isotope is therefore essential when explaining a uranium material's nuclear behavior.
FROM ELEMENT TO APPLICATION
AN ELEMENT IN CONTEXT
Why is uranium dioxide fuel both a nuclear and a materials system?
Uranium dioxide ceramic fuel
FOLLOW THIS RELATIONSHIP
Locate the heat-producing process
Fission in the fuel supplies energy. This nuclear process changes nuclei and must be distinguished from ordinary chemical combustion of a metal in oxygen.
Explore the model (optional)
UFORM → INTERACTION → CONSEQUENCE
Follow the explanation in either direction. These are authored steps, not a physical clock.
Optional: check your understanding
USE THE EXPLANATION
Which description best explains why fuel form matters?
Atomic identity, reference properties and structure models
INTERACTIVE 3D92 visible sites
An electron censusDrag to rotate · scroll or pinch to zoom
[Rn] 5f3 6d1 7s2. Grouping electrons by principal shell connects the neutral-atom configuration to periodic-table patterns.
What this representation means
A three-dimensional counting diagram. Dots are count markers, not measured electron positions; spherical placement and spacing are arbitrary. There are no electron trajectories here. Orbitals describe quantum states.
Martin Heinrich Klaproth identified uranium in 1789 while studying pitchblende, naming it after the recently discovered planet Uranus. His material was an ; Eugène-Melchior Péligot later obtained the metal. Henri Becquerel’s 1896 discovery of radiation from uranium salts opened a different chapter. Uranium thus connects two distinct scientific achievements: recognizing a chemical element and discovering a process occurring inside atomic .
1789
Chemical discovery
Klaproth identifies uranium while analyzing pitchblende.
1896
Radioactivity discovered
Becquerel observes penetrating radiation from uranium salts.
Uranium is found in such as uraninite and carnotite and also occurs at trace levels in many rocks and natural waters. Its have persisted over geological time. A mineral sample contains uranium in particular chemical compounds, while its isotope composition concerns the nuclei within those compounds.
Uranium commonly exhibits +4 and +6 . Uranyl species contain a uranium center bonded to oxygen, illustrating chemistry that cannot be inferred from the appearance of the metal. Different uranium isotopes have broadly similar chemistry but different nuclear properties, a distinction essential to both geological dating and fuel materials.
Each section links its supporting references. Descriptions and diagrams were authored for this atlas. Source checks completed. Source checks dated 2026-09-06.
CITE THIS PAGE
Family labels and the group-3 layout are teaching conventions. A table position does not establish an unknown bulk property. Electronic configurations refer to neutral atoms; ions and material environments require their own account.
Read each reference property together with its units, conditions and the reference information below.
Not yet recorded: electron affinity, second ionization energy, ground-state term symbol, van der waals radius, thermal conductivity, specific heat capacity, electrical resistivity, crystal structure, lattice parameter a, space group, abundance in seawater, abundance in the universe, annual production, supply-risk listing, hazard classification, biological role, cas registry number, pubchem cid, wikidata item. These families are declared and awaiting an ingestion run against the source each names; they are listed here rather than shown as empty rows.
Physical
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Phase at 20 °C
solid
293.15 K, 101.325 kPa
Melting point in K
1405 K
at standard pressure unless noted
Boiling point in K
4404 K
101.325 kPa
Density in g/cm³
18.95 g/cm³
solids and liquids at 293 K; gases at 273 K and 101.325 kPa
Atomic and electronic
Intended reference: Pauling electronegativity scale · Widely tabulated; original in The Nature of the Chemical Bond
Electronegativity in Pauling
1.38 Pauling
Pauling scale
First ionization energy in kJ/mol
597.6 kJ/mol
gas-phase neutral atom, ground state
Covalent radius in pm
196 pm
single-bond covalent radius
Common oxidation states
+4, +6
states met in ordinary compounds; not exhaustive
Occurrence and identity
Intended reference: CRC Handbook of Chemistry and Physics · CRC Press
Abundance in the crust in mg/kg
2.7 mg/kg
upper continental crust, mass fraction
Has stable isotopes
Yesderived
Discovery year in CE
1789 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 7
U 1.38 Pauling · Uranium
Electronegativity across period 7. Exact values.
Ra
0.9
Ac
1.1
Th
1.3
Pa
1.5
U
1.38
Np
1.36
Pu
1.28
Am
1.13
Cm
1.28
Bk
1.3
Cf
1.3
Es
1.3
Fm
1.3
Md
1.3
No
1.3
Lr
1.3
The trend uses the same reference-property values as the periodic table. Elements with no recorded value are left out of the line rather than drawn at zero.
