Palladium is a corrosion-resistant metal used in catalytic converters and other catalysts. Heated palladium allows hydrogen to pass through it, providing a method of separating that gas. It also forms useful alloys, linking chemical selectivity, material structure, and everyday objects such as jewelry.
FROM ELEMENT TO APPLICATION
AN ELEMENT IN CONTEXT
How does a palladium membrane separate hydrogen without acting like a molecular sieve?
Palladium-based metal membrane
FOLLOW THIS RELATIONSHIP
Present a mixed gas
A gas mixture contacts a palladium-based membrane. The separation depends on hydrogen’s interaction with the metal rather than visibly different hole sizes.
Explore the model (optional)
PdFORM → INTERACTION → CONSEQUENCE
Follow the explanation in either direction. These are authored steps, not a physical clock.
Optional: check your understanding
USE THE EXPLANATION
Which change could alter hydrogen transport without enlarging a pore?
Atomic identity, reference properties and structure models
INTERACTIVE 3D46 visible sites
An electron censusDrag to rotate · scroll or pinch to zoom
[Kr] 4d10. 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.
William Hyde Wollaston separated palladium in 1803 but initially offered the material anonymously for sale instead of publishing a full account. Other chemists questioned whether it was truly an element or an . His detailed public explanation followed in 1805. This episode highlights the difference between possessing an unfamiliar material and giving a scientific community enough evidence to evaluate its identity.
1803
Palladium separated
Wollaston obtained the new metal from platinum material.
1805
Identification explained publicly
Wollaston published a fuller account of palladium.
Palladium occurs with platinum-group metals, in such as braggite, and sometimes alloyed naturally with gold. Recovery can accompany nickel processing. These different settings show why an element's presence does not specify a single extraction route: mineral chemistry determines which separations are needed.
Palladium is a corrosion-resistant metal with a notable affinity for hydrogen. Hydrogen can enter and pass through suitable palladium under appropriate conditions. Its behavior is another surface-dependent property. Neither phenomenon means that all gases move through palladium freely or that every palladium object behaves identically.
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
1828 K
at standard pressure unless noted
Boiling point in K
3236 K
101.325 kPa
Density in g/cm³
12.02 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
2.2 Pauling
Pauling scale
First ionization energy in kJ/mol
804.4 kJ/mol
gas-phase neutral atom, ground state
Covalent radius in pm
139 pm
single-bond covalent radius
Common oxidation states
+2, +4
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
0.015 mg/kg
upper continental crust, mass fraction
Has stable isotopes
Yesderived
Discovery year in CE
1803 CEderived
WHERE IT SITS AMONG ITS NEIGHBORS
Electronegativity across period 5
Pd 2.2 Pauling · Palladium
Electronegativity across period 5. Exact values.
Rb
0.82
Sr
0.95
Y
1.22
Zr
1.33
Nb
1.6
Mo
2.16
Tc
1.9
Ru
2.2
Rh
2.28
Pd
2.2
Ag
1.93
Cd
1.69
In
1.78
Sn
1.96
Sb
2.05
Te
2.1
I
2.66
Xe
2.6
Electronegativity down group 10
Pd 2.2 Pauling · Palladium
Electronegativity down group 10. Exact values.
Ni
1.91
Pd
2.2
Pt
2.28
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.
