Thorium

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Thorium Quick Reference

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Notes

Symbol

Th

Atomic Number

90

Atomic Weight

Rounded

232.0

for regular calculations

Standard

232.03806 ± 0.00002

for precise calculations

Oxidation States

4

more common

3

less common

2

less common

Pauling Electronegativity

1.3

Electron Configuration

Orbital Occupancy

[Rn] 6d2 7s2

[Rn] represents the closed-shell electron configuration of radon

Orbital Filling Order

[Rn] 7s2 6d2

[Rn] represents the closed-shell electron configuration of radon

Term Symbol

3F2

see expanded configuration ...

Ionization Energies

I   (1)

 6.3067 eV

II  (2)

11.9 eV   

III (3)

20.0 eV   

IV  (4)

28.8 eV   

Density

solid, 25 °C

11.700 g/cm3

Molar Volume

solid, 298 K, 1 atm

19.80 cm3/mol

Melting Point

2020 ± 10 K

Boiling Point

1 atm

5061.15 K

Thermal Conductivity

solid

400 K

54.5 W/(m K)

300 K

54.0 W/(m K)

298.2 K

54.0 W/(m K)

273.2 K

54.0 W/(m K)

200 K

54.6 W/(m K)

see all 40 conductivities ...

Pyykkö Covalent Radius

single bond

175 pm

double bond

143 pm

triple bond

136 pm

Atomic Radius

180 pm

Enthalpy of Fusion

1 atm

19.2 kJ/mol

Enthalpy of Vaporization

1 atm

543.9 kJ/mol

Quantity

Thorium Atomic Structure

Notes

Ionization Energies

I   (1)

 6.3067 eV

II  (2)

11.9 eV   

III (3)

20.0 eV   

IV  (4)

28.8 eV   

Electron Binding Energies

K    (1s)

109651 eV  

LI   (2s)

 20472 eV  

LII  (2p1/2)

 19693 eV  

LIII (2p3/2)

 16300 eV  

see all 24 energies ...

Electron Configuration

Orbital Occupancy

[Rn] 6d2 7s2

[Rn] represents the closed-shell electron configuration of radon

Orbital Filling Order

[Rn] 7s2 6d2

[Rn] represents the closed-shell electron configuration of radon

Term Symbol

3F2

see expanded configuration ...

Fluorescence Yields

ωK

0.969

ωL1

0.159

ωL2

0.503

ωL3

0.424

Coster-Kronig Yields

F12

0.040

F13

0.62 

F23

0.103

Quantity

Thorium Physical Properties

Notes

Density

solid, 25 °C

11.700 g/cm3

Molar Mass

Rounded

232.0 g/mol

for regular calculations

Standard

232.03806 ± 0.00002 g/mol

for precise calculations

Molar Volume

solid, 298 K, 1 atm

19.80 cm3/mol

Physical Form

soft gray-white metal

Linear Thermal Expansion Coefficient

25 °C

11.0×10-6 K-1

Speed of Sound

solid

2490 m/s

Young's Modulus

78.3 GPa

Poisson's Ratio

0.270

Electrical Resistivity

solid, 295 K

15.2×10-8 Ohm m

Contact Potential

3.46 eV

Photoelectric Work Function

3.47 eV

Thermionic Work Function

3.35 eV

Superconducting Transition Temperature

ambient pressure

1.368 K

0 Pa

1.368 K

Superconducting Critical Magnetic Field at Absolute Zero

1.62×10-4 T

Mineralogical Hardness

3.0

Vickers Hardness

iodide, annealed, 293 K

294 MN/m2 to 392 MN/m2

reduced with calcium, 293 K

589 MN/m2 to 687 MN/m2

Isothermal Bulk Modulus

300 K

54.3 GPa

Isothermal Compressibility

300 K

0.0184 GPa-1

Gram Atomic Volume

20 cm3

Quantity

Thorium Atomic Interaction

Notes

Oxidation States

4

more common

3

less common

2

less common

Pauling Electronegativity

1.3

Allred-Rochow Electronegativity

1.11

Nagle Electronegativity

1.03

Smith Electronegativity

oxidation state: 4

1.35

Cohesive Energy

per mole

598 kJ/mol    

per atom

  6.20 eV/atom

Quantity

Thorium Thermodynamics

Notes

Melting Point

2020 ± 10 K

Boiling Point

1 atm

5061.15 K

Thermal Conductivity

solid

400 K

54.5 W/(m K)

300 K

54.0 W/(m K)

298.2 K

54.0 W/(m K)

273.2 K

54.0 W/(m K)

200 K

54.6 W/(m K)

see all 40 conductivities ...

Critical Point

14550 K

Vapor Pressure

4782 °C

100 kPa

3986 °C

10 kPa

3410 °C

1 kPa

2975 °C

100 Pa

2634 °C

10 Pa

2360 °C

1 Pa

Enthalpy of Fusion

1 atm

19.2 kJ/mol

Enthalpy of Vaporization

1 atm

543.9 kJ/mol

Isobaric Molar Heat Capacity

298.15 K, 1 bar

27.32 J/(mol K)

Isobaric Specific Heat Capacity

298.15 K, 1 bar

0.118 J/(g K)

Electronic Heat Capacity Coefficient

4.08 mJ/(mol K2)

Debye Temperature

Low Temperature Limit ( 0 K )

160 K

Room Temperature ( 298 K )

100 K

Quantity

Thorium Identification

Notes

CAS Number

7440-29-1

DOT Number

metal, pyrophoric

2975

ICSC Number

0337

RTECS Number

XO6400000

UN Number

2912

Quantity

Thorium Atomic Size

Notes

Atomic Radius

180 pm

Orbital Radius

178.8 pm

Pyykkö Covalent Radius

single bond

175 pm

double bond

143 pm

triple bond

136 pm

Cordero Covalent Radius

206 pm

Shannon-Prewitt Crystal Radius

ion charge: +4

coordination number: 6

108 pm

coordination number: 8

119 pm

coordination number: 9

123 pm

coordination number: 10

127 pm

coordination number: 11

132 pm

coordination number: 12

135 pm

Shannon-Prewitt Effective Ionic Radius

ion charge: +4

coordination number: 6

 94 pm

coordination number: 8

105 pm

coordination number: 9

109 pm

coordination number: 10

113 pm

coordination number: 11

118 pm

coordination number: 12

121 pm

Pauling Empirical Crystal Radius

ion charge: +3

114 pm

Batsanov Crystallographic Van Der Waals Radius

2.4×102 pm

Batsanov Equilibrium Van Der Waals Radius

275 pm

Slater Atomic-Ionic Radius

180 pm

Quantity

Thorium Crystal Structure

Notes

Allotropes

allotrope

α-thorium

symbol

αTh

allotrope

β-thorium

symbol

βTh

Nearest Neighbor Distance

300 K, 1 atm

360 pm

Atomic Concentration

300 K, 1 atm

3.04×1022 cm-3

Quantity

Thorium History

Notes

Discovery

date of discovery

1829

discoverer

Jöns Jacob Berzelius

birth

August 20, 1779

death

August 7, 1848

location of discovery

Stockholm, Sweden

Origin of Element Name

origin

Thor

origin description

mythical—The god of war in Norse (or Scandinavian) mythololgy

Origin of Element Symbol

symbol: Th

origin

thorium

origin description

element name

Quantity

Thorium Abundances

Notes

Earth's Crust

9.6 ppm

Earth's Mantle

83.4 ppb

primitive mantle

Bulk Earth

0.055 ppm

Ocean Water

4×10-8 ppm

Metalliferous Ocean Sediment

Basal

2.4 ppm

River Water

0.0001 ppm

U.S. Coal

3.2 ppm

Human Body

0.1 mg

based on a 70 kg "reference man"

Human Bone

0.002 ppm to 0.012 ppm

Human Hair

<0.02 ppm

Ferns

0.42 ppm

Fungi

0.43 ppm

Solar System

0.0335

number of atoms for every 106 atoms of silicon

Sun

0.12 ± 0.06

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

Meteorites

0.079 ± 0.02

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

Quantity

Thorium Nomenclature

Notes

Element Names in Other Languages

French

thorium

German

Thorium

Italian

torio

Spanish

torio

Portuguese

tório

Anions or Anionic Substituent Groups

thoride

Cations or Cationic Substituent Groups

thorium

Ligands

thorido

Heteroatomic Anion

thorate

'a' Term—Substitutive Nomenclature

thora

'y' Term—Chains and Rings Nomenclature

thory

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