#46 / 118
46Pd106.42
Transition Metalssolid at STPD-block

Palladium

Group: 10Period: 5Standard Atomic Weight: 106.42 u

Why is Palladium in this position?

Understanding the scientific rationale behind Palladium's position in the periodic table:

Group Assignment
Group 10

Belongs to Group 10 because it has 10 valence electrons (4d¹⁰ 5s⁰).

Period Assignment
Period 5

Belongs to Period 5 because its filled valence shell is part of the 4d series (n=5 period).

Orbital Block
D-block

Belongs to the d-block because its electron configuration fills the 4d subshell.

Chemical Category
Transition Metals

Classified as a transition metal and precious platinum group metal with peerless catalytic utility.

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 8, 18, 18]

Bohr Atomic Shell Model(2, 8, 18, 18)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

46 Protons (p⁺)60 Neutrons (n⁰)
KShell K: Electron 1 of 2Shell K: Electron 2 of 2LShell L: Electron 1 of 8Shell L: Electron 2 of 8Shell L: Electron 3 of 8Shell L: Electron 4 of 8Shell L: Electron 5 of 8Shell L: Electron 6 of 8Shell L: Electron 7 of 8Shell L: Electron 8 of 8MShell M: Electron 1 of 18Shell M: Electron 2 of 18Shell M: Electron 3 of 18Shell M: Electron 4 of 18Shell M: Electron 5 of 18Shell M: Electron 6 of 18Shell M: Electron 7 of 18Shell M: Electron 8 of 18Shell M: Electron 9 of 18Shell M: Electron 10 of 18Shell M: Electron 11 of 18Shell M: Electron 12 of 18Shell M: Electron 13 of 18Shell M: Electron 14 of 18Shell M: Electron 15 of 18Shell M: Electron 16 of 18Shell M: Electron 17 of 18Shell M: Electron 18 of 18NShell N: Electron 1 of 18Shell N: Electron 2 of 18Shell N: Electron 3 of 18Shell N: Electron 4 of 18Shell N: Electron 5 of 18Shell N: Electron 6 of 18Shell N: Electron 7 of 18Shell N: Electron 8 of 18Shell N: Electron 9 of 18Shell N: Electron 10 of 18Shell N: Electron 11 of 18Shell N: Electron 12 of 18Shell N: Electron 13 of 18Shell N: Electron 14 of 18Shell N: Electron 15 of 18Shell N: Electron 16 of 18Shell N: Electron 17 of 18Shell N: Electron 18 of 18PdZ = 46

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)
Shell L (n=2):8 / 8 electrons (100%)
Shell M (n=3):18 / 18 electrons (100%)
Shell N (n=4):18 / 32 electrons (56%)
Aufbau Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s⁰

Neutral ground state configuration. Valence electrons: 10.

Atomic & Quantum Properties

Electronegativity (Pauling)2.2 Pauling
1st Ionization Energy804.4 kJ/mol
Electron Affinity-53.7 kJ/mol
Atomic Radius (empirical)169 pm
Common Oxidation States+2, +4
Crystal StructureFCC

Physical & Thermal Properties

Density at STP12.02 g/cm³
Melting Point1554.9 °C (1828.05 K)
Boiling Point2963 °C (3236 K)
Magnetic OrderingParamagnetic
Discovery Year1803
Discovered ByWilliam Hyde Wollaston

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses
  • Automotive catalytic converters scrubbing toxic carbon monoxide and hydrocarbons
  • Multilayer ceramic capacitors (MLCC) in smartphones, computers, and tablets
  • Hydrogen purification membrane filters and storage sponges
  • Palladium-catalyzed cross-coupling reactions (Suzuki and Heck couplings, 2010 Nobel Prize)
Occurrence in Nature

Mined from nickel-copper sulfide ores in the Norilsk deposit in Russia, South Africa, and Canada.

Etymology & Name Origin

Named after the asteroid Pallas, which had been discovered two years earlier

Important Chemical Compounds
PdCl₂ (Palladium chloride)
Pd(OAc)₂ (Palladium acetate)
Pd/C (Palladium on carbon catalyst)
Interesting Chemical Facts
  • Palladium is the only element on the periodic table with a closed-shell d-configuration ([Kr] 4d¹⁰) with completely empty outer s-orbitals (5s⁰).
  • Palladium metal absorbs up to 900 times its volume of hydrogen gas like a sponge, expanding noticeably in the process.
  • The 2010 Nobel Prize in Chemistry was awarded to Heck, Negishi, and Suzuki for carbon-carbon bond cross-coupling using palladium catalysts.
Safety & Handling Note

Bulk metal is hypoallergenic and non-toxic, but fine palladium dust can be flammable and may trigger allergic skin dermatitis.