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Pd 46

Palladium (Pd)

transition-metal
Period: 5 Group: 10 Block: d

Solid

Standard Atomic Weight

106.42 u

Electron configuration

[Kr] 4d10

Melting point

1554.9 °C (1828.05 K)

Boiling point

2962.85 °C (3236 K)

Density

1.200000e+4 kg/m³

Oxidation states

+1, +2, +3, +4, +5

Electronegativity (Pauling)

2.2

Ionization energy (1st)

Discovery year

1803

Atomic radius

140 pm

Details

Name origin Named after the asteroid, Pallas, discovered in 1803.
Discovery country England
Discoverers William Wollaston

Palladium is a silvery platinum-group metal with high catalytic activity and an unusual ability to absorb large amounts of hydrogen into its lattice. It is chemically noble in air at ordinary temperatures, but it forms many complexes and is readily used in surface chemistry. Its technological importance is dominated by vehicle emission control, fine-chemical catalysis, electronics, and hydrogen-related applications.

The element is a silvery-white metal, it does not tarnish in air, and it is the least dense and lowest melting of the platinum group of metals. When annealed, it is soft and ductile; cold-working greatly increases its strength and hardness. Palladium is attacked by nitric and sulfuric acid.

At room temperatures, the metal has the unusual property of absorbing up to 900 times its own volume of hydrogen, possibly forming Pd2H. It is not yet clear if this is a true compound. Hydrogen readily diffuses through heated palladium, providing a means of purifying the gas.

The name derives from the second largest asteroid of the solar system Pallas (named after the goddess of wisdom and arts—Pallas Athene). The element was discovered by the English chemist and physicist William Hyde Wollaston in 1803, one year after the discovery of Pallas by the German astronomer Wilhelm Olbers in 1802. The discovery was originally published anonymously by Wollaston to obtain priority, while not disclosing any details about his preparation.

Palladium was discovered by William Hyde Wollaston, an English chemist, in 1803 while analyzing samples of platinum ore that were obtained from South America. Although it is a rare element, palladium tends to occur along with deposits of platinum, nickel, copper, silver and gold and is recovered as a byproduct of mining these other metals.

Palladium was named after the asteroid Pallas, which was discovered at about the same time. Pallas was the Greek goddess of wisdom.

Read about Palladium on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 140 pm
Covalent radius 139 pm
Van der Waals radius 202 pm
Metallic radius 128 pm
Density
Molar volume 0.0089 L/mol
Phase at STP solid
Melting point 1554.9 °C
Boiling point 2962.85 °C
Thermal conductivity 71.8 W/(m·K)
Specific heat capacity 0.246 J/(g·K)
Molar heat capacity 25.98 J/(mol·K)
Crystal structure fcc

Chemical

Electronegativity (Pauling) 2.2
Electronegativity (Allen) 1.58
Electron affinity
Ionization energy (1st)
Ionization energy (2nd)
Ionization energy (3rd)
Ionization energy (4th)
Ionization energy (5th)
Oxidation states +1, +2, +3, +4, +5
Valence electrons 10
Electron configuration
Electron configuration (semantic)

Thermodynamic

Heat of fusion 0.17349847 eV
Heat of vaporization 3.700057 eV
Heat of sublimation 3.907343 eV
Heat of atomization 3.907343 eV
Atomization enthalpy

Nuclear

Stable isotopes 6
Discovery year 1803

Abundance

Abundance (Earth's crust) 0.015 mg/kg

Reactivity

N/A

Crystal Structure

Lattice constant a 389 pm

Electronic Structure

Electrons per shell 2, 8, 18, 18

Identifiers

CAS number 7440-05-3
Term symbol
InChI InChI=1S/Pd
InChI Key KDLHZDBZIXYQEI-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge
Protons 46
Electrons 46
Charge Neutral
Configuration Pd: 4d¹⁰
Electron configuration
Measured
[Kr] 4d¹⁰
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰
Orbital diagram
1s
2/2
2s
2/2
2p
6/6
3s
2/2
3p
6/6
4s
2/2
3d
10/10
4p
6/6
4d
10/10
Total electrons: 46 Unpaired: 0

Atomic model

Protons 46
Neutrons 60
Electrons 46
Mass number 106
Stability Stable

Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.

Schematic atomic model, not to scale.

Atomic Fingerprint

Emission / Absorption Spectrum

25 / 35 (30 with intensity)
Measured
Emission Visible: 380–750 nm
Source: NIST Atomic Spectra Database Wavelengths in air

Isotope Distribution

10627.3300%10826.4600%10522.3300%10411.1400%Mass numberNatural abundance (%)
Mass numberAtomic mass (u)Natural abundanceHalf-life
104 Stable103.9040305 ± 0.000001411.1400%Stable
105 Stable104.9050796 ± 0.000001222.3300%Stable
106 Stable105.9034804 ± 0.000001227.3300%Stable
108 Stable107.9038916 ± 0.000001226.4600%Stable
Measured

Phase / State

1 atm / 101.325 kPa
Solid 25 °C (298.15 K)

Reason: 1529.9 °C below melting point (1554.9 °C)

Melting point 1554.9 °C
Boiling point 2962.85 °C
Below melting by 1529.9 °C
0 K Current temperature: 25 °C 6000 K
Phase timeline

Schematic, not to scale

Solid
Liquid
Gas
Melting
Boiling
25°C
Solid
Liquid
Gas
Current

Phase transition points

Melting point Literature
1554.9 °C
Boiling point Literature
2962.85 °C
Current phase Calculated
Solid

Transition energies

Heat of fusion Literature
0.17349847 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature
3.700057 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature
3.907343 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature
1.200000e+4 kg/m³

At standard conditions

Current density Calculated
1.200000e+4 kg/m³

At standard conditions

Atomic Spectra

Showing 10 of 46 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

IonChargeTotal linesTransition probabilitiesLevel designations
Pd I 076875
Pd II +1621062
Pd III +27500
NIST Lines Holdings →

Levels Holdings ?

IonChargeLevels
Pd I 0145
Pd II +1186
Pd III +2177
Pd IV +32
Pd V +42
Pd VI +52
Pd VII +62
Pd VIII +72
Pd IX +82
Pd X +92
NIST Levels Holdings →
46 Pd 106.42

Palladium — Atomic Orbital Visualizer

[Kr]4d10
Energy levels 2 8 18 18
Oxidation states +1, +2, +3, +4, +5
HOMO 4d n=4 · l=2 · m=-2
Palladium — Atomic Orbital Visualizer Preview
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46 Pd 106.42

Palladium — Crystal Structure Visualizer

Face-Centered Cubic · Pearson cF4
Experimental
Pearson cF4
Coord. № 12
Packing 74.000%
Palladium — Crystal Structure Visualizer Preview
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Ionic Radii

ChargeCoordinationSpinRadius
+12N/A59 pm
+24N/A64 pm
+26N/A86 pm
+36N/A76 pm
+46N/A61.5 pm

Compounds

Pd
106.420 u
Pd+2
106.420 u
Pd
102.906 u
Pd
106.905 u
Pd
108.906 u
Pd
100.908 u
Pd
99.909 u
Pd
104.905 u
Pd
107.904 u
Pd
103.904 u
Pd+2
102.906 u
Pd
111.907 u
Pd
101.906 u
Pd
117.919 u
Pd
105.903 u
Pd
109.905 u

Isotopes (4)

Mass numberAtomic mass (u)Natural abundanceHalf-lifeDecay mode
104 Stable103.9040305 ± 0.000001411.1400% ± 0.0800%Stable
stable
105 Stable104.9050796 ± 0.000001222.3300% ± 0.0800%Stable
stable
106 Stable105.9034804 ± 0.000001227.3300% ± 0.0300%Stable
stable
108 Stable107.9038916 ± 0.000001226.4600% ± 0.0900%Stable
stable
104 Stable
Atomic mass (u) 103.9040305 ± 0.0000014
Natural abundance 11.1400% ± 0.0800%
Half-life Stable
Decay mode
stable
105 Stable
Atomic mass (u) 104.9050796 ± 0.0000012
Natural abundance 22.3300% ± 0.0800%
Half-life Stable
Decay mode
stable
106 Stable
Atomic mass (u) 105.9034804 ± 0.0000012
Natural abundance 27.3300% ± 0.0300%
Half-life Stable
Decay mode
stable
108 Stable
Atomic mass (u) 107.9038916 ± 0.0000012
Natural abundance 26.4600% ± 0.0900%
Half-life Stable
Decay mode
stable

Spectral Lines

Wavelength (nm)IntensityIon stageTypeTransitionAccuracySource
383.2286 nm1500Pd Iemission4d9.(2D<3/2>).5s 2[3/2] → 4d9.(2D<5/2>).5p 2[3/2]*MeasuredNIST
389.41982 nm2200Pd Iemission4d9.(2D<3/2>).5s 2[3/2] → 4d9.(2D<5/2>).5p 2[5/2]*MeasuredNIST
395.86229 nm1500Pd Iemission4d9.(2D<3/2>).5s 2[3/2] → 4d9.(2D<5/2>).5p 2[5/2]*MeasuredNIST
408.73428 nm290Pd Iemission4d9.(2D<3/2>).5s 2[3/2] → 4d9.(2D<5/2>).5p 2[3/2]*MeasuredNIST
416.98387 nm90Pd Iemission4d9.(2D<3/2>).5s 2[3/2] → 4d9.(2D<5/2>).5p 2[3/2]*MeasuredNIST
421.29533 nm2500Pd Iemission4d9.(2D<3/2>).5s 2[3/2] → 4d9.(2D<5/2>).5p 2[7/2]*MeasuredNIST
447.35846 nm180Pd Iemission4d9.(2D<3/2>).5s 2[3/2] → 4d9.(2D<5/2>).5p 2[3/2]*MeasuredNIST
478.81874 nmN/APd Iemission4d9.(2D<5/2>).5p 2[3/2]* → 4d9.(2D<5/2>).5d 2[5/2]MeasuredNIST
481.75067 nmN/APd Iemission4d9.(2D<5/2>).5p 2[3/2]* → 4d9.(2D<5/2>).5d 2[3/2]MeasuredNIST
487.54251 nm35Pd Iemission4d9.(2D<5/2>).5p 2[3/2]* → 4d9.(2D<5/2>).5d 2[1/2]MeasuredNIST
511.08092 nm55Pd Iemission4d9.(2D<5/2>).5p 2[7/2]* → 4d9.(2D<5/2>).5d 2[7/2]MeasuredNIST
511.70072 nm75Pd Iemission4d9.(2D<3/2>).5p 2[5/2]* → 4d9.(2D<3/2>).5d 2[7/2]MeasuredNIST
516.38405 nm160Pd Iemission4d9.(2D<5/2>).5p 2[7/2]* → 4d9.(2D<5/2>).5d 2[9/2]MeasuredNIST
523.48612 nm55Pd Iemission4d9.(2D<5/2>).5p 2[7/2]* → 4d9.(2D<5/2>).5d 2[7/2]MeasuredNIST
529.56266 nm120Pd Iemission4d9.(2D<5/2>).5p 2[7/2]* → 4d9.(2D<5/2>).5d 2[9/2]MeasuredNIST
531.25867 nm18Pd Iemission4d9.(2D<5/2>).5p 2[3/2]* → 4d9.(2D<5/2>).5d 2[5/2]MeasuredNIST
534.51048 nm15Pd Iemission4d9.(2D<3/2>).5p 2[5/2]* → 4d9.(2D<3/2>).5d 2[5/2]MeasuredNIST
539.52204 nm35Pd Iemission4d9.(2D<3/2>).5p 2[5/2]* → 4d9.(2D<3/2>).5d 2[7/2]MeasuredNIST
554.28067 nm55Pd Iemission4d9.(2D<5/2>).5p 2[5/2]* → 4d9.(2D<5/2>).5d 2[7/2]MeasuredNIST
554.70204 nm35Pd Iemission4d9.(2D<5/2>).5p 2[5/2]* → 4d9.(2D<5/2>).5d 2[5/2]MeasuredNIST
561.94631 nm27Pd Iemission4d9.(2D<3/2>).5p 2[3/2]* → 4d9.(2D<3/2>).5d 2[5/2]MeasuredNIST
564.27039 nm15Pd Iemission4d9.(2D<3/2>).5p 2[1/2]* → 4d9.(2D<3/2>).5d 2[3/2]MeasuredNIST
565.54366 nm14Pd Iemission4d9.(2D<3/2>).5p 2[3/2]* → 4d9.(2D<3/2>).5d 2[5/2]MeasuredNIST
567.00702 nm75Pd Iemission4d9.(2D<5/2>).5p 2[5/2]* → 4d9.(2D<5/2>).5d 2[7/2]MeasuredNIST
569.0128 nm11Pd Iemission4d9.(2D<3/2>).5p 2[1/2]* → 4d9.(2D<3/2>).5d 2[3/2]MeasuredNIST
569.50921 nmN/APd Iemission4d9.(2D<5/2>).5p 2[5/2]* → 4d9.(2D<5/2>).5d 2[5/2]MeasuredNIST
573.66175 nm18Pd Iemission4d9.(2D<5/2>).5p 2[5/2]* → 4d9.(2D<5/2>).5d 2[3/2]MeasuredNIST
677.45174 nm23Pd Iemission4d8.5s2 3F → 4d9.(2D<3/2>).5p 2[5/2]*MeasuredNIST
678.44893 nm65Pd Iemission4d9.(2D<5/2>).5p 2[3/2]* → 4d9.(2D<5/2>).6s 2[5/2]MeasuredNIST
683.3446 nmN/APd Iemission4d9.(2D<3/2>).5p 2[3/2]* → 4d9.(2D<5/2>).5d 2[5/2]MeasuredNIST
701.6446 nm11Pd Iemission4d9.(2D<3/2>).5p 2[1/2]* → 4d9.(2D<3/2>).6s 2[3/2]MeasuredNIST
731.0053 nmN/APd Iemission4d9.(2D<3/2>).5p 2[5/2]* → 4d9.(2D<3/2>).6s 2[3/2]MeasuredNIST
736.8096 nm75Pd Iemission4d9.(2D<5/2>).5p 2[7/2]* → 4d9.(2D<5/2>).6s 2[5/2]MeasuredNIST
739.19 nm27Pd Iemission4d9.(2D<3/2>).5p 2[5/2]* → 4d9.(2D<3/2>).6s 2[3/2]MeasuredNIST
748.6909 nm16Pd Iemission4d9.(2D<5/2>).5p 2[7/2]* → 4d9.(2D<5/2>).6s 2[5/2]MeasuredNIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)  
Covalent radius (Pyykkö, double)  
Covalent radius (Pyykkö, triple)  

Van der Waals Radii

Batsanov  
Alvarez  
UFF  
MM3  

Atomic & Metallic Radii

Atomic radius (Rahm)  
Metallic radius (C12)  

Numbering Scales

Mendeleev
Pettifor
Glawe

Electronegativity Scales

Ghosh
Miedema
Gunnarsson–Lundqvist
Robles–Bartolotti

Polarizability & Dispersion

Dipole polarizability  
Dipole polarizability (unc.)  
C₆ (Gould–Bučko)  

Chemical Affinity

Proton affinity  
Gas basicity  

Miedema Parameters

Miedema molar volume  
Miedema electron density

Supply Risk & Economics

Production concentration
Relative supply risk
Reserve distribution
Political stability (top producer)
Political stability (top reserve)

Phase Transitions & Allotropes

Melting point1827.95 K
Boiling point3236.15 K

Oxidation State Categories

+2 main
+1 extended
+3 extended
+4 main
+5 extended

Advanced Reference Data

Screening Constants (9)
nOrbitalσ
1s0.9411
2p4.07
2s12.1172
3d14.5489
3p16.9804
3s16.7788
4d32.3824
4p28.2768
4s27.014
Crystal Radii Detail (5)
ChargeCNSpinrcrystal (pm)Origin
1II73
2IVSQ78
2VI100
3VI90
4VI75.5from r^3 vs V plots,
Isotope Decay Modes (62)
IsotopeModeIntensity
90B+—
90B+p—
902p—
91B+100%
91B+p3.1%
92B+100%
92B+p1.6%
93B+100%
93B+p7.4%
94B+100%
X‑ray Scattering Factors (507)
Energy (eV)f₁f₂
10—1.15058
10.1617—1.2095
10.3261—1.27144
10.4931—1.33655
10.6628—1.40499
10.8353—1.47694
11.0106—1.54695
11.1886—1.61473
11.3696—1.68548
11.5535—1.75934

Additional Data

Sources

Sources of this element.

Discovered in 1803 by Wollaston, Palladium is found with platinum and other metals of the platinum group in placer deposits of Russia, South America, North America, Ethiopia, and Australia. It is also found associated with the nickel-copper deposits of South Africa and Ontario. Palladium's separation from the platinum metals depends upon the type of ore in which it is found.

References (1)

References

(9)
2 Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)
Pd

The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.

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3 IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)
Palladium

Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.

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4 IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.

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License note: Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.
5 Jefferson Lab, U.S. Department of Energy
Palladium

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/

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License note: Please see citation and linking information: https://education.jlab.org/faq/index.html
6 Los Alamos National Laboratory, U.S. Department of Energy
Palladium

The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.

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7 NIST Physical Measurement Laboratory
Palladium

The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database

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8 PubChem Elements
Palladium

This section provides all form of data related to element Palladium.

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9 PubChem Elements
Palladium

The element property data was retrieved from publications.

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Data verified:

Content is reviewed against latest scientific data.