Iridium

Iridium Navigation

Other Elements

By Name

By Symbol

By Number

Solutions manuals and the Numerari scientific calculator from KnowledgeDoor Learn more about our solutions
manuals Learn more about Numerari

Quantity

Iridium Quick Reference

Click button to see citations

Notes

Symbol

Ir

Atomic Number

77

Atomic Weight

Rounded

192.2

for regular calculations

Standard

192.217 ± 0.003

for precise calculations

Oxidation States

 6

less common

 5

less common

 4

more common

 3

more common

 2

less common

 1

less common

 0

less common

-1

less common

Pauling Electronegativity

2.20

Electron Configuration

Orbital Occupancy

[Xe] 4f14 5d7 6s2

[Xe] represents the closed-shell electron configuration of xenon

Orbital Filling Order

[Xe] 6s2 4f14 5d7

[Xe] represents the closed-shell electron configuration of xenon

Term Symbol

4F9/2

see expanded configuration ...

Ionization Energies

I (1)

8.96702 eV

Electron Affinity

1.56436 ± 0.00015 eV

12617.4 ± 1.2 cm-1  

Density

liquid, 2719.15 K

20.000 g/ml 

solid

400 K

22.515 g/cm3

crystallographic

300 K

22.559 g/cm3

crystallographic

20 °C

22.562 ± 0.009 g/cm3

290 K

22.563 g/cm3

crystallographic

280 K

22.568 g/cm3

crystallographic

270 K

22.572 g/cm3

crystallographic

see all 47 densities ...

Molar Volume

solid, 298 K, 1 atm

8.52 cm3/mol

Melting Point

1 atm

2719 K

ITS-90 first-quality, secondary reference point (freezing point)

Boiling Point

1 atm

4898 ± 50 K

reference stated that the uncertainty may be larger than indicated

Thermal Conductivity

solid

400 K

144 W/(m K)

300 K

147 W/(m K)

298.2 K

147 W/(m K)

273.2 K

148 W/(m K)

200 K

153 W/(m K)

see all 42 conductivities ...

Pyykkö Covalent Radius

single bond

122 pm

double bond

115 pm

triple bond

107 pm

Atomic Radius

136 pm

Enthalpy of Fusion

1 atm

26.4 kJ/mol

Enthalpy of Vaporization

1 atm

563.6 kJ/mol

Quantity

Iridium Atomic Structure

Notes

Ionization Energies

I (1)

8.96702 eV

Electron Affinity

1.56436 ± 0.00015 eV

12617.4 ± 1.2 cm-1  

Electron Binding Energies

K    (1s)

76111 eV  

LI   (2s)

13419 eV  

LII  (2p1/2)

12824 eV  

LIII (2p3/2)

11215 eV  

see all 19 energies ...

Electron Configuration

Orbital Occupancy

[Xe] 4f14 5d7 6s2

[Xe] represents the closed-shell electron configuration of xenon

Orbital Filling Order

[Xe] 6s2 4f14 5d7

[Xe] represents the closed-shell electron configuration of xenon

Term Symbol

4F9/2

see expanded configuration ...

Clementi-Raimondi Effective Nuclear Charge

1s

Orbital Exponent

75.5119

ζ

Principle Quantum Number

1

n

Effective Nuclear Charge

75.5119

Zeff = ζ × n

2s

Orbital Exponent

28.4449

ζ

Principle Quantum Number

2

n

Effective Nuclear Charge

56.8898

Zeff = ζ × n

see all 14 effective nuclear charges ...

Screening Percentage

86.1%

Fluorescence Yields

ωK

0.958

ωL1

0.145

ωL2

0.331

ωL3

0.292

Coster-Kronig Yields

F12

0.076

F13

0.482

F23

0.128

Quantity

Iridium Physical Properties

Notes

Density

liquid, 2719.15 K

20.000 g/ml 

solid

400 K

22.515 g/cm3

crystallographic

300 K

22.559 g/cm3

crystallographic

20 °C

22.562 ± 0.009 g/cm3

290 K

22.563 g/cm3

crystallographic

280 K

22.568 g/cm3

crystallographic

270 K

22.572 g/cm3

crystallographic

see all 47 densities ...

Molar Mass

Rounded

192.2 g/mol

for regular calculations

Standard

192.217 ± 0.003 g/mol

for precise calculations

Molar Volume

solid, 298 K, 1 atm

8.52 cm3/mol

Physical Form

silvery-white metal

Linear Thermal Expansion Coefficient

25 °C

6.4×10-6 K-1

283 K

6.65×10-6 K-1

85 K

3.90×10-6 K-1

75 K

3.43×10-6 K-1

65 K

2.88×10-6 K-1

57.5 K

2.37×10-6 K-1

see all 20 coefficients ...

Speed of Sound

solid, 293 K

4800 m/s to 4850 m/s

calculated value

Young's Modulus

528 GPa

Poisson's Ratio

0.262

Electrical Resistivity

solid, 295 K

5.1×10-8 Ohm m

Contact Potential

4.57 eV

Thermionic Work Function

5.3 eV

Superconducting Transition Temperature

0.1125 ± 0.0005 K

Superconducting Critical Magnetic Field at Absolute Zero

19×10-4 T

Mineralogical Hardness

6.5

Vickers Hardness

annealed at 2273 K, purity - 99.93%

293 K

1760 MN/m2

673 K

1410 MN/m2

see all 5 hardnesses ...

Reflectivity

surface polished

1.0 μm

78%

2.0 μm

87%

4.0 μm

94%

see all 6 reflectivities ...

Isothermal Bulk Modulus

300 K

355 GPa

Isothermal Compressibility

300 K

0.00282 GPa-1

Gram Atomic Volume

9 cm3

Quantity

Iridium Atomic Interaction

Notes

Oxidation States

 6

less common

 5

less common

 4

more common

 3

more common

 2

less common

 1

less common

 0

less common

-1

less common

Pauling Electronegativity

2.20

Allred-Rochow Electronegativity

1.55

Configuration Energy

electron volt units

9.96 eV

Pauling units

1.68   

Allred Electronegativity

oxidation state: 2

2.20

Nagle Electronegativity

1.43

Pearson Absolute Electronegativity

5.4 eV

Chemical Hardness

3.8 eV

Cohesive Energy

per mole

670 kJ/mol    

per atom

  6.94 eV/atom

Quantity

Iridium Thermodynamics

Notes

Melting Point

1 atm

2719 K

ITS-90 first-quality, secondary reference point (freezing point)

Boiling Point

1 atm

4898 ± 50 K

reference stated that the uncertainty may be larger than indicated

Thermal Conductivity

solid

400 K

144 W/(m K)

300 K

147 W/(m K)

298.2 K

147 W/(m K)

273.2 K

148 W/(m K)

200 K

153 W/(m K)

see all 42 conductivities ...

Critical Point

7800 K

Vapor Pressure

4898 K

1 atm

4894 K

1 bar

4193 K

1×10-1 bar

3681 K

1×10-2 bar

2719 K

9.837×10-6 bar

melting point

see all 19 pressures ...

Enthalpy of Fusion

1 atm

26.4 kJ/mol

Enthalpy of Vaporization

1 atm

563.6 kJ/mol

Isobaric Molar Heat Capacity

298.15 K, 1 bar

25.10 J/(mol K)

Isobaric Specific Heat Capacity

298.15 K, 1 bar

0.131 J/(g K)

Electronic Heat Capacity Coefficient

3.14 mJ/(mol K2)

Debye Temperature

Low Temperature Limit ( 0 K )

420 K

Room Temperature ( 298 K )

228 K

Quantity

Iridium Identification

Notes

CAS Number

7439-88-5

Quantity

Iridium Atomic Size

Notes

Atomic Radius

136 pm

Orbital Radius

122.7 pm

Pyykkö Covalent Radius

single bond

122 pm

double bond

115 pm

triple bond

107 pm

Cordero Covalent Radius

141 pm

Shannon-Prewitt Crystal Radius

ion charge: +3, coordination number: 6

82 pm  

ion charge: +4, coordination number: 6

76.5 pm

ion charge: +5, coordination number: 6

71 pm  

Shannon-Prewitt Effective Ionic Radius

ion charge: +3, coordination number: 6

68 pm  

ion charge: +4, coordination number: 6

62.5 pm

ion charge: +5, coordination number: 6

57 pm  

Batsanov Crystallographic Van Der Waals Radius

2.0×102 pm

Batsanov Equilibrium Van Der Waals Radius

234 pm

Slater Atomic-Ionic Radius

135 pm

Quantity

Iridium Crystal Structure

Notes

Nearest Neighbor Distance

300 K, 1 atm

271 pm

Atomic Concentration

300 K, 1 atm

7.06×1022 cm-3

Quantity

Iridium History

Notes

Discovery

date of discovery

1804

discoverer

Smithson Tennant

birth

November 30, 1761

death

February 22, 1815

location of discovery

London, England

Origin of Element Name

origin

iris

origin description

color—Latin for rainbow

Origin of Element Symbol

symbol: Ir

origin

iridium

origin description

element name

Formerly Used or Proposed Element Names and Symbols

symbol

I

Quantity

Iridium Abundances

Notes

Earth's Crust

1×10-3 ppm

Earth's Mantle

3.2 ppb

primitive mantle

Earth's Core

2.6 ppm

Bulk Earth

0.9 ppm

Metalliferous Ocean Sediment

Ridge

0.8 ppb

U.S. Coal

<0.001 ppm

estimated from USGS and literature data

Solar System

0.661

number of atoms for every 106 atoms of silicon

Sun

1.35 ± 0.10

base 10 log of the number of atoms for every 1012 atoms of hydrogen

Meteorites

1.35 ± 0.01

base 10 log of the number of atoms for every 1012 atoms of hydrogen

Quantity

Iridium Nomenclature

Notes

Element Names in Other Languages

French

iridium

German

Iridium

Italian

iridio

Spanish

iridio

Portuguese

irídio

Anions or Anionic Substituent Groups

iridide

Cations or Cationic Substituent Groups

iridium

Ligands

iridido

Heteroatomic Anion

iridate

'a' Term—Substitutive Nomenclature

irida

'y' Term—Chains and Rings Nomenclature

iridy

References    (Click the button next to a value above to see complete citation information for that entry)

A., J. W. "Osmium, the Densest Metal Known." Platinum Metals Review, volume 39, number 4, 1995, p. 164.

Allred, A. L. "Electronegativity Values from Thermochemical Data." Journal of Inorganic and Nuclear Chemistry, volume 17, number 3-4, 1961, pp. 215–221. doi:10.1016/0022-1902(61)80142-5

Anders, Edward, and Nicolas Grevesse. "Abundances of the Elements: Meteoritic and Solar." Geochimica et Cosmochimica Acta, volume 53, number 1, 1989, pp. 197–214. doi:10.1016/0016-7037(89)90286-X

Andersen, T., H. K. Haugen, and H. Hotop. "Binding Energies in Atomic Negative Ions: III." Journal of Physical and Chemical Reference Data, volume 28, number 6, 1999, pp. 1511–1533.

Arblaster, J. W. "Crystallographic Properties of Iridium: Assessment of Properties from Absolute Zero to the Melting Point." Platinum Metals Review, volume 54, number 2, 2010, pp. 93–102. doi:10.1595/147106710X493124

Arblaster, J. W. "Vapour Pressure Equations for the Platinum Group Elements." Platinum Metals Review, volume 51, number 3, 2007, pp. 130–135. doi:10.1595/147106707X213830

Arblaster, J. W. "Thermodynamic Properties of the Platinum Metals on ITS-90." Platinum Metals Review, volume 40, number 2, 1996, pp. 62–63.

Ball, David W. "Elemental Etymology: What's in a Name?" Journal of Chemical Education, volume 62, number 9, 1985, pp. 787–788. doi:10.1021/ed062p787

Batsanov, S. S. "Van der Waals Radii of Elements." Inorganic Materials, volume 37, number 9, 2001, pp. 871–885. See abstract

Bedford, R. E., G. Bonnier, H. Maas, and F. Pavese. "Recommended Values of Temperature on the International Temperature Scale of 1990 for a Selected Set of Secondary Reference Points." Metrologia, volume 33, number 2, 1996, pp. 133–154. doi:10.1088/0026-1394/33/2/3

Campbell, J. L. "Fluorescence Yields and Coster–Kronig Probabilities for the Atomic L Subshells. Part II: The L1 Subshell Revisited." Atomic Data and Nuclear Data Tables, volume 95, number 1, 2009, pp. 115–124. doi:10.1016/j.adt.2008.08.002

Campbell, J. L. "Fluorescence Yields and Coster–Kronig Probabilities for the Atomic L Subshells." Atomic Data and Nuclear Data Tables, volume 85, number 2, 2003, pp. 291–315. doi:10.1016/S0092-640X(03)00059-7

Cardarelli, François. Materials Handbook: A Concise Desktop Reference, 2nd edition. London: Springer–Verlag, 2008.

Clementi, E., D. L. Raimondi, and W. P. Reinhardt. "Atomic Screening Constants from SCF Functions. II. Atoms with 37 to 86 Electrons." Journal of Chemical Physics, volume 47, number 4, 1967, pp. 1300–1307. doi:10.1063/1.1712084

Cohen, E. Richard, David R. Lide, and George L. Trigg, editors. AlP Physics Desk Reference, 3rd edition. New York: Springer-Verlag New York, Inc., 2003.

Connelly, Neil G., Ture Damhus, Richard M. Hartshorn, and Alan T. Hutton. Nomenclature of Inorganic Chemistry: IUPAC Recommendations 2005. Cambridge: RSC Publishing, 2005.

Cordero, Beatriz, Verónica Gómez, Ana E. Platero-Prats, Marc Revés, Jorge Echeverría, Eduard Cremades, Flavia Barragán, and Santiago Alvarez. "Covalent Radii Revisited." Dalton Transactions, number 21, 2008, pp 2832–2838. doi:10.1039/b801115j

Davies, B. J., C. W. Ingram, D. J. Larson, and U. Ljungblad. "The Electron Affinity of Iridium." Journal of Chemical Physics, volume 106, number 13, 1997, pp. 5783–5784. doi:10.1063/1.473602

de Podesta, Michael. Understanding the Properties of Matter, 2nd edition. London: Taylor & Francis, 2002.

Dronskowski, Richard. Computational Chemistry of Solid State Materials. Weinheim, Germany: WILEY-VCH Verlag GmbH & Co. KGaA, 2005.

Emsley, John. Nature's Building Blocks: An A-Z Guide to the Elements. Oxford: Oxford University Press, 2003.

Emsley, John. The Elements, 3rd edition. Oxford: Oxford University Press, 1998.

Firestone, Richard B. Table of Isotopes, 8th edition, volume 2. Edited by Virginia S. Shirley, with assistant editors Coral M. Baglin, S. Y. Frank Chu, and Jean Zipkin. New York: John Wiley & Sons, Inc., 1996.

Greenwood, N. N., and A. Earnshaw. Chemistry of the Elements, 2nd edition. Oxford: Butterworth-Heinemann, 1997.

Griffith, W. P. "Bicentenary of Four Platinum Group Metals: Part II: Osmium and Iridium—Events Surrounding Their Discoveries." Platinum Metals Review, volume 48, number 4, 2004, pp. 182–189. doi:10.1595/147106704X4844

Gubser, D. U., and R. J. Soulen. "Thermodynamic Properties of Superconducting Iridium." Journal of Low Temperature Physics, volume 13, number 3-4, 1973, pp. 211–226. doi:10.1007/BF00654062

Gwyn Williams. Electron Binding Energies. http://www.jlab.org/~gwyn/ebindene.html. Accessed on April 30, 2010.

Ho, C. Y., R. W. Powell, and P. E. Liley. "Thermal Conductivity of the Elements: A Comprehensive Review." Journal of Physical and Chemical Reference Data, volume 3, supplement 1, 1974, pp. I–1 to I–796.

Höhne, G. W. H., W. F. Hemminger, and H.-J. Flammersheim. Differential Scanning Calorimetry, 2nd edition. Berlin: Springer–Verlag, 2003.

Horvath, A. L. "Critical Temperature of Elements and the Periodic System." Journal of Chemical Education, volume 50, number 5, 1973, pp. 335–336. doi:10.1021/ed050p335

Huheey, James E., Ellen A. Keiter, and Richard L Keiter. Inorganic Chemistry: Principles of Structure and Reactivity, 4th edition. New York: HarperCollins College Publishers, 1993.

Ihde, Aaron J. The Development of Modern Chemistry. New York: Dover Publications, Inc., 1984.

Jr., Elbert J. Little,, and Mark M. Jones. "A Complete Table of Electronegativities." Journal of Chemical Education, volume 37, number 5, 1960, pp. 231–233. doi:10.1021/ed037p231

Kittel, Charles. Introduction to Solid State Physics, 8th edition. Hoboken, NJ: John Wiley & Sons, Inc, 2005.

Lewis, David G. "The Early Life of Smithson Tennant FRS (1761–1815)." Platinum Metals Review, volume 55, number 3, 2011, pp. 196–200. doi:10.1595/147106711X581710

Li, Y.-H., and J. E. Schoonmaker. "Chemical Composition and Mineralogy of Marine Sediments." pp. 1–36 in Sediments, Diagenesis, and Sedimentary Rocks. Edited by Fred T. Mackenzie. Oxford: Elsevier Ltd., 2005.

Liboff, Richard L. Introductory Quantum Mechanics, 3rd edition. Reading, MA: Addison Wesley Longman, Inc., 1998.

Lide, David R., editor. CRC Handbook of Chemistry and Physics, 88th edition. Boca Raton, Florida: Taylor & Francis Group, 2008.

Mann, Joseph B., Terry L. Meek, Eugene T. Knight, Joseph F. Capitani, and Leland C. Allen. "Configuration Energies of the d-Block Elements." Journal of the American Chemical Society, volume 122, number 21, 2000, pp. 5132–5137. doi:10.1021/ja9928677

Manuel, O., editor. Origin of Elements in the Solar System: Implications of Post-1957 Observations. New York: Kluwer Academic Publishers, 2000.

Marshall, James L. Discovery of the Elements: A Search for the Fundamental Principles of the Universe, 2nd edition. Boston, MA: Pearson Custom Publishing, 2002.

Martin, W. C. "Electronic Structure of the Elements." The European Physical Journal C — Particles and Fields, volume 15, number 1–4, 2000, pp. 78–79. doi:10.1007/BF02683401

McDonough, W. F. "Compositional Model for the Earth's Core." pp. 547–568 in The Mantle and Core. Edited by Richard W. Carlson. Oxford: Elsevier Ltd., 2005.

Mechtly, Eugene A. "Properties of Materials." pp. 4–1 to 4–33 in Reference Data For Engineers: Radio, Electronics, Computer, and Communications. By Mac E. Van Valkenburg, edited by Wendy M. Middleton. Woburn, MA: Butterworth-Heinemann, 2002. doi:10.1016/B978-075067291-7/50006-6

Miessler, Gary L., and Donald A. Tarr. Inorganic Chemistry, 3rd edition. Upper Saddle River, NJ: Pearson Prentice Hall, 2004.

Nagle, Jeffrey K. "Atomic Polarizability and Electronegativity." Journal of the American Chemical Society, volume 112, number 12, 1990, pp. 4741–4747. doi:10.1021/ja00168a019

Nicholas, J. V., and D. R. White. "Temperature." pp. 8–41 in Measurement of the Thermodynamic Properties of Single Phases. Edited by A. R. H. Goodwin, W. A. Wakeham, and K. N. Marsh. Amsterdam: Elsevier Science, 2003.

Orem, W. H., and R. B. Finkelman. "Coal Formation and Geochemistry." pp. 191–222 in Sediments, Diagenesis, and Sedimentary Rocks. Edited by Fred T. Mackenzie. Oxford: Elsevier Ltd., 2005.

Oxtoby, David W., H. P. Gillis, and Alan Campion. Principles of Modern Chemistry, 6th edition. Belmont, CA: Thomson Brooks/Cole, 2008.

Palme, H., and H. Beer. "Meteorites and the Composition of the Solar Photosphere." pp. 204–206 in Landolt–Börnstein—Group VI: Astronomy and Astrophysics. Edited by H. H. Voigt. New York: Springer–Verlag, 1993. doi:10.1007/10057790_59

Palme, H., and Hugh St. C. O'Neill. "Cosmochemical Estimates of Mantle Composition." pp. 1–38 in The Mantle and Core. Edited by Richard W. Carlson. Oxford: Elsevier Ltd., 2005.

Pearson, Ralph G. "Absolute Electronegativity and Hardness: Application to Inorganic Chemistry." Inorganic Chemistry, volume 27, number 4, 1988, pp 734–740. doi:10.1021/ic00277a030

Pekka Pyykkö. Self-Consistent, Year-2009 Covalent Radii. http://www.chem.helsinki.fi/~pyykko/Radii09.pdf. Accessed on November 20, 2010.

Pyykkö, Pekka, and Michiko Atsumi. "Molecular Double-Bond Covalent Radii for Elements Li-E112." Chemistry - A European Journal, volume 15, number 46, 2009, pp. 12770–12779. doi:10.1002/chem.200901472

Pyykkö, Pekka, and Michiko Atsumi. "Molecular Single-Bond Covalent Radii for Elements 1-118." Chemistry - A European Journal, volume 15, number 1, 2009, pp. 186–197. doi:10.1002/chem.200800987

Pyykkö, Pekka, Sebastian Riedel, and Michael Patzschke. "Triple-Bond Covalent Radii." Chemistry - A European Journal, volume 11, number 12, 2005, pp. 3511–3520. doi:10.1002/chem.200401299

Samsonov, G. V., editor. Handbook of the Physicochemical Properties of the Elements. New York: Plenum Publishing Corporation, 1968.

Sansonetti, J. E., and W. C. Martin. "Handbook of Basic Atomic Spectroscopic Data." Journal Of Physical And Chemical Reference Data, volume 34, number 4, 2005, pp. 1559–2259. doi:10.1063/1.1800011

Shannon, R. D. "Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides." Acta Crystallographica Section A, volume 32, number 5, 1976, pp. 751–767. doi:10.1107/S0567739476001551

Silbey, Robert J., Robert A. Alberty, and Moungi G. Bawendi. Physical Chemistry, 4th edition. Hoboken, NJ: John Wiley & Sons, Inc., 2005.

Singman, Charles N. "Atomic Volume and Allotropy of the Elements." Journal of Chemical Education, volume 61, number 2, 1984, pp. 137–142. doi:10.1021/ed061p137

Slater, J. C. "Atomic Radii in Crystals." The Journal of Chemical Physics, volume 41, number 10, 1964, pp. 3199–3204. doi:10.1063/1.1725697

Smith, Derek W. Inorganic Substances: A Prelude to the Study of Descriptive Inorganic Chemistry. Cambridge: Cambridge University Press, 1990.

Soukhanov, Anne H., editor. The American Heritage Dictionary Of The English Language, 3rd edition. Boston: Houghton Mifflin Company, 1992.

Stewart, G. R. "Measurement of low-temperature specific heat." Review of Scientific Instruments, volume 54, number 1, 1983, pp. 1–11. doi:10.1063/1.1137207

Stewart, G. R. "Measurement of Low-Temperature Specific Heat." Review of Scientific Instruments, volume 54, number 1, 1983, pp. 1–11. doi:10.1063/1.1137207

Tari, A. The Specific Heat of Matter at Low Temperatures. London: Imperial College Press, 2003.

Tennant, Smithson. "On Two Metals, Found in the Black Powder Remaining after the Solution of Platina." Philosophical Transactions of the Royal Society of London, volume 94, 1804, pp. 411–418. doi:10.1098/rstl.1804.0018

Vainshtein, Boris K., Vladimir M. Fridkin, and Vladimir L. Indenbom. Structure of Crystals, 2nd edition. Modern Crystallography 2. Edited by Boris K. Vainshtein, A. A. Chernov, and L. A. Shuvalov. Berlin: Springer-Verlag, 1995.

Voigt, H. H., editor. Landolt–Börnstein—Group VI Astronomy and Astrophysics. Berlin: Springer–Verlag, 1993.

Waber, J. T., and Don T. Cromer. "Orbital Radii of Atoms and Ions." Journal of Chemical Physics, volume 42, number 12, 1965, pp. 4116–4123. doi:10.1063/1.1695904

Wagman, Donald D., William H. Evans, Vivian B. Parker, Richard H. Schumm, Iva Halow, Sylvia M. Bailey, Kenneth L. Churney, and Ralph L. Nuttall. "Thermal Conductivity of the Elements: A Comprehensive Review." Journal of Physical and Chemical Reference Data, volume 11, supplement 2, 1982, pp. 2–1 to 2–392.

Waldron, Kimberley A., Erin M. Fehringer, Amy E. Streeb, Jennifer E. Trosky, and Joshua J. Pearson. "Screening Percentages Based on Slater Effective Nuclear Charge as a Versatile Tool for Teaching Periodic Trends." Journal of Chemical Education, volume 78, number 5, 2001, pp. 635–639. doi:10.1021/ed078p635

Weeks, Mary Elvira, and Henry M. Leicester. Discovery of the Elements, 7th edition. Easton, PA: Journal of Chemical Education, 1968.

White, G. K., and A. T. Pawlowicz. "Thermal Expansion of Rhodium, Iridium, and Palladium at Low Temperatures." Journal of Low Temperature Physics, volume 2, number 5-6, 1970, pp. 631–639. doi:10.1007/BF00628279

Wieser, Michael E., and Tyler B. Coplen. "Atomic weights of the elements 2009 (IUPAC Technical Report)." Pure and Applied Chemistry, volume 83, number 2, 2011, pp. 359–396. doi:10.1351/PAC-REP-10-09-14

Yaws, Carl L. "Liquid Density of the Elements." Chemical Engineering, volume 114, number 12, 2007, pp. 44–46.

Yaws, Carl L. The Yaws Handbook of Physical Properties for Hydrocarbons and Chemicals. Houston, TX: Gulf Publishing Company, 2005.