|
Some useful data and physical properties
for relatively pure unalloyed tantilum are listed below. Because
published values vary data sources referenced should be consulted
for precision applications.
|
| Discoverer
¹ |
Ekeberg,
1802
|
| Named
for ¹ |
Tantalos
(Greek), Mythological Father of Niobe
|
| Abundance
in Earth’s Crust ¹ |
Fiftieth,
2 g/metric ton
|
| Chemical
Symbol ¹ |
Ta
|
| Color
¹ |
Gray-Black
|
| Atomic
Number ¹ |
73
|
| Standard
Atomic Weight (1989) ¹ |
180.9479
|
| Atomic
Volume ³ |
10.9
cm³/mol
|
| Lattice
Constant at 20°C³ |
3.3026
|
| Density
¹ |
4.54
gm/cm³ (0.1640 lbs/in³)
|
| Hardness
³ |
Rockwell
B 35
|
| Elastic
Modulus in Tension ²·³ |
E = 27.0 x 10
psi
|
| Poisson's
Ratio ²·³ |
0.35
|
| Thermal
Expansion Coefficient (25°C)¹ |
6.3
x 10 cm/cm/°C (3.5 x 10
in/in/°F) |
Thermal
Conductivity ( )at
27°C ¹ |
49.47
Kcal /h·m·°C
(33.24 BTU/h·ft²·°F/ft.)(0.575 W/cm·K) |
| Melting
Point,. Tm,
1 Atm. ¹ |
3020°C
(5468°F) |
| Boiling
Point, Tb, 1 Atm. ¹ |
5457
± 100°C (9856°F) |
Enthalpy
of Fusion, 
fusH,
J/g ¹ |
199
J/g |
| Enthalpy,
H° ¹ |
782
kJ/mol |
| Gibbs
Energy of Formation,
fG°
¹ |
739.3
kJ/mol (gaseous state) |
| Standard
Entropy, S° (25°C) ¹ |
41.5
J/mol·C (crystalline state) |
| Standard
Entropy, S° (25°C) ¹ |
185.2
J/mol·C (gaseous state) |
| Specific
Heat Capacity, Cp
(25°C) ¹ |
25.4
J/mol (crystalline state) |
| Specific
Heat Capacity, Cp (25°C)
¹ |
20.9
J/mol (gaseous state) |
| Specific
Electrical Resistivity ¹ |
12.2
micro-ohms
/cm/cm² (at 20°C) |
Electrical
Conductivity |
12.79%
of pure copper |
| Superconductive
Transformation Temp.² |
4.3°K |
| Specific
Magnetic Susceptibility (20°C)¹ |
+154
x 10
cgs |
Emissivity,
 , at 500°K
 |
0.08 |
| Nuclear
Cross Section ³ |
21.3
barns/atom |
| First
Ionization Potential ¹ |
I
- 7.89 eV |
| Room
Temperature Structure ³ |
Body
Centered Cubic (BCC) |
| Standard
Reduction Potential, E0 25°C
¹ |
-0.750
(Ta2O5
+ 10 H+ + 3e  2
Ta+ 5 H2O) |
| Electron
Work Function ¹ |
4.25
eV |
| Oxides
and Oxidation States ¹ |
Ta203, +5
|
| Valence
¹ |
+2(?),
+3, +4(?), +5 |
| Electron
Configuration ¹ |
-32-11-2 |
