Palladium commonly forms Pd2+ Pd4+ in introductory ionic compounds.
| Element | Palladium |
|---|---|
| Symbol | Pd |
| Atomic number | 46 |
| Common ionic charge | +2, +4 |
| Common ions | Pd2+, Pd4+ |
Images are used as visual references; charge rules still depend on the compound.
Palladium is the only element whose ground state is a completely filled outer d shell with no s electrons: [Kr]4d10. Removing two electrons gives the square-planar d8 Pd2+ so beloved of coordination chemists; the full d10 also lets the neutral metal soak up hydrogen like a sponge — up to 900 times its own volume.
This is a classroom reference range, not an exhaustive list of all oxidation states.
Writing palladium(II) chloride's dissolved form as bare Pd2+. In hydrochloric acid it travels as the complex ion PdCl4 2- — the +2 palladium hides inside a 2- package. Transition-metal 'simple salts' are often complexes in disguise.
The catalytic loop alternates Pd(0) and Pd(II): the neutral atom inserts into a carbon-halogen bond (becoming +2), swaps in the second carbon partner, then releases the joined product and returns to 0. Every modern pharmacy shelf carries molecules built this way.
Palladium chloride
Pd2+ balances chloride ions.
Palladium oxide
Palladium can form oxides where total positive and negative charge balances.
As a neutral alloying metal it whitens gold and resists tarnish. Skin sensitization can occur when trace Pd2+ ions leach — the ionic form, not the metal itself, is the allergen.
H2 molecules split into atoms on the neutral metal's surface and diffuse through its lattice; nothing else passes. It is charge-0 chemistry — the d10 metal bonding hydrogen atoms without ever ionizing.
The 1989 claims involved deuterium-loaded palladium electrodes. The electrochemistry (Pd absorbing D) was real; the nuclear fusion was not reproducible. The episode is now a case study in extraordinary-evidence standards.
Combine positive and negative ions so the total charge is zero — or let the ionic compound calculator do the crossing for you. The full chart lives on the periodic table with charges.
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