
106 Part 2 The Elements
Table 2.1-16B(a) Elements of Group VB (CAS notation), or Group 5 (new IUPAC notation). Crystallographic properties
Element name Vanadium Niobium Tantalum Dubnium
Chemical symbol V Nb Ta Db
Atomic number Z 23 41 73 105
Units Remarks
Crystal system, Bravais lattice cub, bc cub, bc cub, bc
Structure type W W W
Lattice constant a 302.38 330.07 330.31 pm
Space group Im3m Im3m Im3m
Schoenflies symbol O
9
h
O
9
h
O
9
h
Strukturbericht type A2 A2 A2
Pearson symbol cI2 cI2 cI2
Number A of atoms per cell 2 2 2
Coordination number 8 8 8
Shortest interatomic 263 285 285 pm
distance, solid
Table 2.1-16B(b) Elements of Group VB (CAS notation), or Group 5 (new IUPAC notation). Mechanical properties
Element name Vanadium Niobium Tantalum Dubnium
Chemical symbol V Nb Ta Db
Atomic number Z 23 41 73 105
Units Remarks
Density , solid 5.80 8.35 16.60 g/cm
3
Density , liquid 5.55 7.830 15,00 g/cm
3
Molar volume V
mol
8.34 10.84 10.87 cm
3
/mol
Surface tension, liquid 1.95 2.0 2.15 N/m
Temperature coefficient 0.3×10
−3
−0.24×10
−3
−0.25×10
−3
N/(mK)
Coefficient of linear 8.3× 10
−6
7.34× 10
−6
6.64× 10
−6
1/K 300 K
thermal expansion α
Sound velocity, 2780 2100 2900 m/s
solid, transverse
Sound velocity, 6000 4900 4100 m/s
solid, longitudinal
Compressibility κ 0.63 × 10
−5
0.56× 10
−5
0.465× 10
−5
1/MPa Volume
compressibility
Elastic modulus E 127 104 185 GPa
Shear modulus G 46.6 59.5 64.7 GPa
Poisson number µ 0.36 0.38 0.35
Elastic compliance s
11
6.75 6.56 6.89 1/TPa
Elastic compliance s
44
23.2 35.2 12.1 1/TPa
Elastic compliance s
12
−2.31 −2.29 −2.58 1/TPa
Elastic stiffness c
11
230 245 264 GPa
Elastic stiffness c
44
43.1 28.4 82.6 GPa
Elastic stiffness c
12
120 132 158 GPa
Vickers hardness 630 70–250 80–300 At 293 K
(HV 10) (HV 10)
Part 2 1.5