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Properties of substance:

tantalum

Group of substances:

inorganic

Physical appearance:

gray cubic metal

Empirical formula (Hill's system for organic substances):

Ta

Structural formula as text:

Ta

Molar/atomic mass: 180.95

Melting point (°C):

3015

Boiling point (°C):

5500

Solubility (g/100 g of solvent):

gallium: 0.01 (450°C) [Ref.]
gallium: 1.3 (800°C) [Ref.]
mercury: insoluble [Ref.]
water: sparingly soluble [Ref.]

Numerical data:

Year of discovery: 1802
Superconducting temperature (K): 4.46

Density:

16.6 (20°C, g/cm3)

Reactions:

  1. [Ref.1, Ref.2, Ref.3]
    2Ta + 5F2 → 2TaF5

Half-life:

15573Ta = 3.2 ms (p (100%))
15673Ta = 106 ms (p (71%), β+ (29%))
156m73Ta = 360 ms (β+ (95.8%), p (4.2%))
15773Ta = 10.1 ms ()
15873Ta = 49 ms (α (96%))
158m73Ta = 36.0 ms (α (95%))
158n73Ta = 6.1 μs (internal transition (98.6%), α (1.4%))
15973Ta = 1.04 s (α (34%))
159m73Ta = 560 ms (α (55%))
16073Ta = 1.70 s ()
160m73Ta = 1.55 s ()
161m73Ta = 3.08 s ()
16273Ta = 3.57 s (β+ (about 100%), α (0.074%))
16373Ta = 10.6 s (β+ (about 100%), α (about 0.2%))
16473Ta = 14.2 s (β+ (100%))
16573Ta = 31.0 s (β+ (100%))
16673Ta = 34.4 s (β+ (100%))
16773Ta = 1.33 min (β+ (100%))
16873Ta = 2.0 min (β+ (100%))
16973Ta = 4.9 min (β+ (100%))
17073Ta = 6.76 min (β+ (100%))
17173Ta = 23.3 min (β+ (100%))
17273Ta = 36.8 min (β+ (100%))
17373Ta = 3.14 h (β+ (100%))
17473Ta = 1.14 h (β+ (100%))
17573Ta = 10.5 h (β+ (100%))
17673Ta = 8.09 h (β+ (100%))
176m73Ta = 1.08 ms (internal transition (100%))
176n73Ta = 3.8 μs (internal transition (100%))
176p73Ta = 970 μs (internal transition (100%))
17773Ta = 56.56 h (β+ (100%))
177m73Ta = 410 ns (internal transition (100%))
177n73Ta = 3.62 μs (internal transition (100%))
177p73Ta = 5.31 μs (internal transition (100%))
177q73Ta = 133 μs (internal transition (100%))
17873Ta = 2.36 h (β+ (100%))
178m73Ta = 9.31 min (β+ (100%))
178n73Ta = 59 ms (internal transition (100%))
178p73Ta = 290 ms (internal transition (100%))
17973Ta = 1.82 y (electron capture (100%))
179m73Ta = 1.42 μs (internal transition (100%))
179n73Ta = 280 ns (internal transition (100%))
179p73Ta = 322 ns (internal transition (100%))
179q73Ta = 9.0 ms (internal transition (100%))
179r73Ta = 1.6 μs (internal transition (100%))
179x73Ta = 54.1 ms (internal transition (100%))
18073Ta = 8.154 h (electron capture (85%), β+ (15%))
180m73Ta = stable ( (isotopic abundance 0,01201%))
180n73Ta = 31.2 μs (internal transition (100%))
180p73Ta = 2.0 μs (internal transition (100%))
180q73Ta = 17 μs (internal transition (100%))
18173Ta = stable ( (isotopic abundance 99,98799%))
181m73Ta = 6.05 μs (internal transition (100%))
181n73Ta = 18 μs (internal transition (100%))
181p73Ta = 140 ns (internal transition (100%))
181q73Ta = 25.2 μs (internal transition (100%))
181r73Ta = 210 μs (internal transition (100%))
18273Ta = 114.74 d (β- (100%))
182m73Ta = 283 ms (internal transition (100%))
182n73Ta = 15.84 min (internal transition (100%))
18373Ta = 5.1 d (β- (100%))
183m73Ta = 106 ns (internal transition (100%))
183n73Ta = 900 ns (internal transition (100%))
18473Ta = 8.7 h (β- (100%))
18573Ta = 49.4 min (β- (100%))
185m73Ta = 900 ns (internal transition (100%))
185n73Ta = 11.8 ms (internal transition (100%))
18673Ta = 10.5 min (β- (100%))
186m73Ta = 1.54 min ()
18773Ta = 2.3 min ()
187m73Ta = 22 s ()
18873Ta = 19.6 s (β- (100%))
188m73Ta = 3.6 μs (internal transition (100%))
189m73Ta = 1.6 μs (internal transition (100%))
19073Ta = 5.3 s (β- (100%))
190m73Ta = 42 ns (internal transition (100%))
19273Ta = 2.2 s (β- (100%))

Vapour pressure (Torr):

0.0000000031 (1927°C)
0.01 (3056°C)
0.1 (3352°C)
1 (3705°C)
10 (4135°C)
100 (4680°C)

Standard molar enthalpy (heat) of formation ΔfH0 (298.15 K, kJ/mol):

0 (s)

Standard molar Gibbs energy of formation ΔfG0 (298.15 K, kJ/mol):

0 (s)

Standard molar entropy S0 (298.15 K, J/(mol·K)):

41.5 (s)

Molar heat capacity at constant pressure Cp (298.15 K, J/(mol·K)):

25.36 (s)

Molar enthalpy (heat) of fusion ΔfusH (kJ/mol):

34.7

Enthalpy (heat) of vaporization ΔvapH (kJ/mol):

744.8

References:

  1. Гибало И.М. Аналитическая химия ниобия и тантала. - М.: Наука, 1967. - pp. 5-16 [Russian]
  2. Ниобий и тантал. - М.: Металлургия, 1990 [Russian]
  3. Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 102 [Russian]
  4. Химическая энциклопедия. - Т. 4. - М.: Советская энциклопедия, 1995. - pp. 494-495 [Russian]

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    © Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru