Thermal Conductivity of Chemical Elements

Periodic Table of Elements - thermal conductivity
1
H

Hydrogen

0.1805 W/m K

2
He

Helium

0.1513 W/m K

3
Li

Lithium

85 W/m K

4
Be

Beryllium

190 W/m K

5
B

Boron

27 W/m K

6
C

Carbon

140 W/m K

7
N

Nitrogen

0.0258 W/m K

8
O

Oxygen

0.0266 W/m K

9
F

Fluorine

0.0277 W/m K

10
Ne

Neon

0.0491 W/m K

11
Na

Sodium

140 W/m K

12
Mg

Magnesium

160 W/m K

13
Al

Aluminium

235 W/m K

14
Si

Silicon

150 W/m K

15
P

Phosphorus

0.236 W/m K

16
S

Sulfur

0.205 W/m K

17
Cl

Chlorine

0.0089 W/m K

18
Ar

Argon

0.0177 W/m K

19
K

Potassium

100 W/m K

20
Ca

Calcium

200 W/m K

21
Sc

Scandium

16 W/m K

22
Ti

Titanium

22 W/m K

23
V

Vanadium

31 W/m K

24
Cr

Chromium

94 W/m K

25
Mn

Manganese

7.8 W/m K

26
Fe

Iron

80 W/m K

27
Co

Cobalt

100 W/m K

28
Ni

Nickel

91 W/m K

29
Cu

Copper

400 W/m K

30
Zn

Zinc

120 W/m K

31
Ga

Gallium

29 W/m K

32
Ge

Germanium

60 W/m K

33
As

Arsenic

50 W/m K

34
Se

Selenium

0.52 W/m K

35
Br

Bromine

0.12 W/m K

36
Kr

Krypton

0.0094 W/m K

37
Rb

Rubidium

58 W/m K

38
Sr

Strontium

35 W/m K

39
Y

Yttrium

17 W/m K

40
Zr

Zirconium

23 W/m K

41
Nb

Niobium

54 W/m K

42
Mo

Molybdenum

139 W/m K

43
Tc

Technetium

51 W/m K

44
Ru

Ruthenium

120 W/m K

45
Rh

Rhodium

150 W/m K

46
Pd

Palladium

72 W/m K

47
Ag

Silver

430 W/m K

48
Cd

Cadmium

97 W/m K

49
In

Indium

82 W/m K

50
Sn

Tin

67 W/m K

51
Sb

Antimony

24 W/m K

52
Te

Tellurium

3 W/m K

53
I

Iodine

0.449 W/m K

54
Xe

Xenon

0.0057 W/m K

55
Cs

Caesium

36 W/m K

56
Ba

Barium

18 W/m K

57-71

 

Lanthanoids

 

72
Hf

Hafnium

23 W/m K

73
Ta

Tantalum

57 W/m K

74
W

Tungsten

170 W/m K

75
Re

Rhenium

48 W/m K

76
Os

Osmium

88 W/m K

77
Ir

Iridium

150 W/m K

78
Pt

Platinum

72 W/m K

79
Au

Gold

320 W/m K

80
Hg

Mercury

8.3 W/m K

81
Tl

Thallium

46 W/m K

82
Pb

Lead

35 W/m K

83
Bi

Bismuth

8 W/m K

84
Po

Polonium

 

85
At

Astatine

2 W/m K

86
Rn

Radon

0.0036 W/m K

87
Fr

Francium

 

88
Ra

Radium

19 W/m K

89-103

 

Actinoids

 

104
Rf

Rutherfordium

 

105
Db

Dubnium

 

106
Sg

Seaborgium

 

107
Bh

Bohrium

 

108
Hs

Hassium

 

109
Mt

Meitnerium

 

110
Ds

Darmstadtium

 

111
Rg

Roentgenium

 

112
Cn

Copernicium

 

113
Nh

Nihonium

 

114
Fl

Flerovium

 

115
Mc

Moscovium

 

116
Lv

Livermorium

 

117
Ts

Tennessine

 

118
Og

Oganesson

 

57
La

Lanthanum

13 W/m K

58
Ce

Cerium

11 W/m K

59
Pr

Praseodymium

13 W/m K

60
Nd

Neodymium

17 W/m K

61
Pm

Promethium

15 W/m K

62
Sm

Samarium

13 W/m K

63
Eu

Europium

14 W/m K

64
Gd

Gadolinium

11 W/m K

65
Tb

Terbium

11 W/m K

66
Dy

Dysprosium

11 W/m K

67
Ho

Holmium

16 W/m K

68
Er

Erbium

15 W/m K

69
Tm

Thulium

17 W/m K

70
Yb

Ytterbium

39 W/m K

71
Lu

Lutetium

16 W/m K

89
Ac

Actinium

12 W/m K

90
Th

Thorium

54 W/m K

91
Pa

Protactinium

47 W/m K

92
U

Uranium

27 W/m K

93
Np

Neptunium

6 W/m K

94
Pu

Plutonium

6 W/m K

95
Am

Americium

10 W/m K

96
Cm

Curium

 

97
Bk

Berkelium

10 W/m K

98
Cf

Californium

 

99
Es

Einsteinium

 

100
Fm

Fermium

 

101
Md

Mendelevium

 

102
No

Nobelium

 

103
Lr

Lawrencium

 

Thermal Conductivity of Chemical Elements

The heat transfer characteristics of a solid material are measured by a property called the thermal conductivity, k (or λ), measured in W/m.K. It is a measure of a substance’s ability to transfer heat through a material by conduction. Note that Fourier’s law applies for all matter, regardless of its state (solid, liquid, or gas), therefore, it is also defined for liquids and gases.

The thermal conductivity of most liquids and solids varies with temperature. For vapors, it also depends upon pressure. In general:

thermal conductivity - definition

Most materials are very nearly homogeneous, therefore we can usually write k = k (T). Similar definitions are associated with thermal conductivities in the y- and z-directions (ky, kz), but for an isotropic material the thermal conductivity is independent of the direction of transfer, kx = ky = kz = k.

 

Thermal Conductivity of Metals

Transport of thermal energy in solids may be generally due to two effects:
  • the migration of free electrons
  • lattice vibrational waves (phonons)

When electrons and phonons carry thermal energy leading to conduction heat transfer in a solid, the thermal conductivity may be expressed as:

k = ke + kph

thermal conductivity - metalsMetals are solids and as such they possess crystalline structure where the ions (nuclei with their surrounding shells of core electrons) occupy translationally equivalent positions in the crystal lattice. Metals in general have high electrical conductivityhigh thermal conductivity, and high density. Accordingly, transport of thermal energy may be due to two effects:

  • the migration of free electrons
  • lattice vibrational waves (phonons).

When electrons and phonons carry thermal energy leading to conduction heat transfer in a solid, the thermal conductivity may be expressed as:

k = ke + kph

The unique feature of metals as far as their structure is concerned is the presence of charge carriers, specifically electrons. The electrical and thermal conductivities of metals originate from the fact that their outer electrons are delocalized. Their contribution to the thermal conductivity is referred to as the electronic thermal conductivity, ke. In fact, in pure metals such as gold, silver, copper, and aluminum, the heat current associated with the flow of electrons by far exceeds a small contribution due to the flow of phonons. In contrast, for alloys, the contribution of kph to k is no longer negligible.

Thermal Conductivity of Nonmetals

thermal conductivity - building materialsFor nonmetallic solidsk is determined primarily by kph, which increases as the frequency of interactions between the atoms and the lattice decreases. In fact, lattice thermal conduction is the dominant thermal conduction mechanism in nonmetals, if not the only one. In solids, atoms vibrate about their equilibrium positions (crystal lattice). The vibrations of atoms are not independent of each other, but are rather strongly coupled with neighboring atoms. The regularity of the lattice arrangement has an important effect on kph, with crystalline (well-ordered) materials like quartz having a higher thermal conductivity than amorphous materials like glass. At sufficiently high temperatures kph ∝ 1/T.

The quanta of the crystal vibrational field are referred to as ‘‘phonons.’’ A phonon is a collective excitation in a periodic, elastic arrangement of atoms or molecules in condensed matter, like solids and some liquids. Phonons play a major role in many of the physical properties of condensed matter, like thermal conductivity and electrical conductivity. In fact, for crystalline, nonmetallic solids such as diamond, kph can be quite large, exceeding values of k associated with good conductors, such as aluminum. In particular, diamond has the highest hardness and thermal conductivity (k = 1000 W/m.K) of any bulk material.

 

Thermal Conductivity of Liquids and Gases

In physics, a fluid is a substance that continually deforms (flows) under an applied shear stress. Fluids are a subset of the phases of matter and include liquidsgases, plasmas and, to some extent, plastic solids. Because the intermolecular spacing is much larger and the motion of the molecules is more random for the fluid state than for the solid state, thermal energy transport is less effective. The thermal conductivity of gases and liquids is therefore generally smaller than that of solids. In liquids, the thermal conduction is caused by atomic or molecular diffusion. In gases, the thermal conduction is caused by diffusion of molecules from higher energy level to the lower level.

Thermal Conductivity of Gases

thermal conductivity - gasesThe effect of temperature, pressure, and chemical species on the thermal conductivity of a gas may be explained in terms of the kinetic theory of gases. Air and other gases are generally good insulators, in the absence of convection. Therefore, many insulating materials (e.g.polystyrene) function simply by having a large number of gas-filled pockets which prevent large-scale convection. Alternation of gas pocket and solid material causes that the heat must be transferred through many interfaces causing rapid decrease in heat transfer coefficient.

The thermal conductivity of gases is directly proportional to the density of the gas, the mean molecular speed, and especially to the mean free path of molecule. The mean free path also depends on the diameter of the molecule, with larger molecules more likely to experience collisions than small molecules, which is the average distance traveled by an energy carrier (a molecule) before experiencing a collision. Light gases, such as hydrogen and helium typically have high thermal conductivity. Dense gases such as xenon and dichlorodifluoromethane have low thermal conductivity.

In general, the thermal conductivity of gases increases with increasing temperature.

Thermal Conductivity of Liquids

As was written, in liquids, the thermal conduction is caused by atomic or molecular diffusion, but physical mechanisms for explaining the thermal conductivity of liquids are not well understood. Liquids tend to have better thermal conductivity than gases, and the ability to flow makes a liquid suitable for removing excess heat from mechanical components. The heat can be removed by channeling the liquid through a heat exchanger. The coolants used in nuclear reactors include water or liquid metals, such as sodium or lead.

The thermal conductivity of nonmetallic liquids generally decreases with increasing temperature.

Properties of other elements