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Potassium Quick Reference

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Notes

Symbol

K

Atomic Number

19

Atomic Weight

Rounded

39.10

for regular calculations

Standard

39.0983 ± 0.0001

for precise calculations

Oxidation States

 1

more common

-1

less common

Pauling Electronegativity

0.82

Electron Configuration

Orbital Occupancy

[Ar] 4s1

[Ar] represents the closed-shell electron configuration of argon

Orbital Filling Order

[Ar] 4s1

[Ar] represents the closed-shell electron configuration of argon

Term Symbol

2S1/2

see expanded configuration ...

Ionization Energies

I   (1)

 4.3406633 eV    

II  (2)

31.63 eV         

III (3)

45.806 ± 0.010 eV

IV  (4)

60.91 ± 0.05 eV  

see all 19 energies ...

Electron Affinity

0.501459 ± 0.000012 eV

 4044.54 ± 0.10 cm-1  

Density

liquid, 336.35 K

0.828 g/ml 

solid

25 °C

0.890 g/cm3

5 K

0.910 g/cm3

Molar Volume

solid, 298 K, 1 atm

45.94 cm3/mol

Melting Point

1 bar

336.35 K

Boiling Point

1 atm

1031.00 K

Thermal Conductivity

liquid, 400 K

 52.0 W/(m K)

solid

300 K

102.4 W/(m K)

298.2 K

102.5 W/(m K)

273.2 K

103.6 W/(m K)

extrapolated, interpolated, or estimated

200 K

104.3 W/(m K)

extrapolated, interpolated, or estimated

see all 50 conductivities ...

Pyykkö Covalent Radius

single bond

196 pm

double bond

193 pm

Atomic Radius

235 pm

Enthalpy of Fusion

1 atm

2.4 kJ/mol

Enthalpy of Vaporization

1 atm

77.53 kJ/mol

Quantity

Potassium Atomic Structure

Notes

Ionization Energies

I   (1)

 4.3406633 eV    

II  (2)

31.63 eV         

III (3)

45.806 ± 0.010 eV

IV  (4)

60.91 ± 0.05 eV  

see all 19 energies ...

Electron Affinity

0.501459 ± 0.000012 eV

 4044.54 ± 0.10 cm-1  

Electron Binding Energies

K    (1s)

3608.4 eV

LI   (2s)

 378.6 eV

LII  (2p1/2)

 297.3 eV

LIII (2p3/2)

 294.6 eV

see all 7 energies ...

Electron Configuration

Orbital Occupancy

[Ar] 4s1

[Ar] represents the closed-shell electron configuration of argon

Orbital Filling Order

[Ar] 4s1

[Ar] represents the closed-shell electron configuration of argon

Term Symbol

2S1/2

see expanded configuration ...

Clementi-Raimondi Effective Nuclear Charge

1s

Orbital Exponent

18.4895

ζ

Principle Quantum Number

1

n

Effective Nuclear Charge

18.4895

Zeff = ζ × n

2s

Orbital Exponent

 6.5031

ζ

Principle Quantum Number

2

n

Effective Nuclear Charge

13.006 

Zeff = ζ × n

see all 6 effective nuclear charges ...

Screening Percentage

88.4%

Fluorescence Yields

ωK

0.143  

ωL1

0.00024

ωL2

0.00027

ωL3

0.00027

Coster-Kronig Yields

F12

0.31

F13

0.62

Quantity

Potassium Physical Properties

Notes

Density

liquid, 336.35 K

0.828 g/ml 

solid

25 °C

0.890 g/cm3

5 K

0.910 g/cm3

Molar Mass

Rounded

39.10 g/mol

for regular calculations

Standard

39.0983 ± 0.0001 g/mol

for precise calculations

Molar Volume

solid, 298 K, 1 atm

45.94 cm3/mol

Physical Form

soft silvery-white metal

Linear Thermal Expansion Coefficient

25 °C

83.3×10-6 K-1

Speed of Sound

liquid

673 K

1706.5 m/s

373 K

1868.4 m/s

80 °C, longitudinal wave

1869 m/s  

solid

2000 m/s  

Young's Modulus

3.175 GPa

Poisson's Ratio

0.350

Electrical Resistivity

solid

200 K

4.26×10-8 Ohm m

273.15 K

6.49×10-8 Ohm m

293 K

7.20×10-8 Ohm m

300 K

7.47×10-8 Ohm m

liquid, 400 K

17.18×10-8 Ohm m

see all 55 resistivities ...

Contact Potential

1.60 eV

Photoelectric Work Function

2.24 eV

Mineralogical Hardness

0.4

Isothermal Bulk Modulus

300 K

3.2 GPa

Isothermal Compressibility

300 K

0.31 GPa-1

Gram Atomic Volume

46 cm3

Quantity

Potassium Atomic Interaction

Notes

Oxidation States

 1

more common

-1

less common

Pauling Electronegativity

0.82

Mulliken-Jaffe Electronegativity

orbitals

0.73

Sanderson Electronegativity

0.445

Allred-Rochow Electronegativity

0.91

Configuration Energy

electron volt units

4.340 eV

Pauling units

0.734   

Allen Electronegativity

0.734

Allred Electronegativity

oxidation state: 1

0.82

Boyd-Edgecombe Electronegativity

0.99

Ghosh-Gupta Electronegativity

2.0027 eV

Nagle Electronegativity

0.84

Pearson Absolute Electronegativity

2.42 eV

Smith Electronegativity

oxidation state: 1

0.8

Free Electron Fermi Surface Parameters

5 K

electron concentration

1.40×1022 cm-3

radius parameter

4.86

fermi wavevector

0.75×108 cm-1

fermi velocity

0.86×108 cm/s

fermi energy

2.12 eV

fermi temperature

2.46×104 K

Chemical Hardness

1.92 eV

Cohesive Energy

per mole

90.1 kJ/mol   

per atom

 0.934 eV/atom

Quantity

Potassium Thermodynamics

Notes

Melting Point

1 bar

336.35 K

Boiling Point

1 atm

1031.00 K

Thermal Conductivity

liquid, 400 K

 52.0 W/(m K)

solid

300 K

102.4 W/(m K)

298.2 K

102.5 W/(m K)

273.2 K

103.6 W/(m K)

extrapolated, interpolated, or estimated

200 K

104.3 W/(m K)

extrapolated, interpolated, or estimated

see all 50 conductivities ...

Critical Point

2223 K

Vapor Pressure

756.2 °C

100 kPa

559 °C

10 kPa

424 °C

1 kPa

see all 16 pressures ...

Enthalpy of Fusion

1 atm

2.4 kJ/mol

Enthalpy of Vaporization

1 atm

77.53 kJ/mol

Isobaric Molar Heat Capacity

298.15 K, 1 bar

29.600 J/(mol K)

Isobaric Specific Heat Capacity

298.15 K, 1 bar

0.757 J/(g K)

Electronic Heat Capacity Coefficient

2.08 mJ/(mol K2)

Debye Temperature

Low Temperature Limit ( 0 K )

 91.1 K

Room Temperature ( 298 K )

100 K  

Quantity

Potassium Identification

Notes

CAS Number

7440-09-7

DOT Number

2257

metal

2257

ICSC Number

0716

RTECS Number

TS6460000

UN Number

2257

Quantity

Potassium Atomic Size

Notes

Atomic Radius

235 pm

Orbital Radius

216.2 pm

Pyykkö Covalent Radius

single bond

196 pm

double bond

193 pm

Cordero Covalent Radius

203 pm

Shannon-Prewitt Crystal Radius

ion charge: +1

coordination number: 4

151 pm

coordination number: 6

152 pm

coordination number: 7

160 pm

coordination number: 8

165 pm

coordination number: 9

169 pm

coordination number: 10

173 pm

coordination number: 12

178 pm

Shannon-Prewitt Effective Ionic Radius

ion charge: +1

coordination number: 4

137 pm

coordination number: 6

138 pm

coordination number: 7

146 pm

coordination number: 8

151 pm

coordination number: 9

155 pm

coordination number: 10

159 pm

coordination number: 12

164 pm

Pauling Empirical Crystal Radius

ion charge: +1

133 pm

Pauling Univalent Radius

ion charge: +1

133 pm

Batsanov Crystallographic Van Der Waals Radius

2.8×102 pm

Batsanov Equilibrium Van Der Waals Radius

302 pm

Bondi Van Der Waals Radius

275 pm

Slater Atomic-Ionic Radius

220 pm

Quantity

Potassium Crystal Structure

Notes

Nearest Neighbor Distance

5 K, 1 atm

452.5 pm

Atomic Concentration

5 K, 1 atm

1.402×1022 cm-3

Quantity

Potassium History

Notes

Discovery

date of discovery

1807

discoverer

Humphry Davy

birth

December 17, 1778

death

May 29, 1829

location of discovery

London, England

Origin of Element Name

origin

potash

origin description

mineral—English

Origin of Element Symbol

symbol: K

origin

kalium

origin description

word—Mediaeval Latin for potash

Formerly Used or Proposed Element Names and Symbols

symbol

Ka

symbol

Po

Quantity

Potassium Abundances

Notes

Earth's Crust

2.09×104 ppm

Earth's Mantle

260 ppm

primitive mantle

Bulk Earth

160 ppm

Ocean Water

416 ppm

Metalliferous Ocean Sediment

Basal

1.15%

River Water

2.3 ppm

U.S. Coal

0.18%

Human Body

140 g

based on a 70 kg "reference man"

Human Bone

2100 ppm

Human Hair

150 ppm to 660 ppm

Human Kidney

8×103 ppm

Human Liver

8.5×103 ppm

Human Muscle

16×103 ppm

Human Nail

360 ppm to 2800 ppm

Bacteria

115×103 ppm

Ferns

18×103 ppm

Fungi

22×103 ppm

Solar System

3770

number of atoms for every 106 atoms of silicon

Sun

5.12 ± 0.13

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

Meteorites

5.11 ± 0.02

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

Halley's Comet

0.2 ± 0.1 atoms

number of atoms for every 100 atoms of magnesium

Quantity

Potassium Nomenclature

Notes

Element Names in Other Languages

French

potassium

German

Kalium

Italian

potassio

Spanish

potasio

Portuguese

potássio

Anions or Anionic Substituent Groups

potasside

Cations or Cationic Substituent Groups

potassium

Ligands

potassido

Heteroatomic Anion

potassate

'a' Term—Substitutive Nomenclature

potassa

'y' Term—Chains and Rings Nomenclature

potassy

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