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Properties of substance:
radium
Group of substances:
inorganic
Physical appearance:
cubic metal
Empirical formula (Hill's system for organic substances):
Ra
Structural formula as text:
Ra
Molar/atomic mass: 226.0254
Melting point (°C):
969
Boiling point (°C):
1507
Solubility (g/100 g of solvent):
water
: reaction [
Ref.
]
Numerical data:
Year of discovery: 1898
Ionization Potentials (Electronvolts): 5.277
Ionization Potentials (Electronvolts): 10.144
Density:
6 (20°C, g/cm
3
)
Reactions:
[
Ref.1
,
Ref.2
]
Ra + 2H
2
O → Ra(OH)
2
+ H
2
Half-life:
201
88
Ra = 20 ms (α (100%))
202
88
Ra = 31 ms (α (100%))
203
88
Ra = 36 ms (α (about 100%))
204
88
Ra = 60 ms (α (about 100%))
205
88
Ra = 220 ms ()
205m
88
Ra = 180 ms ()
206
88
Ra = 240 ms ()
207
88
Ra = 1.38 s (α (about 86%))
207m
88
Ra = 57 ms ()
208
88
Ra = 1.11 s (α (87%))
208m
88
Ra = 263 ns (internal transition (100%))
209
88
Ra = 4.71 s (α (about 90%), β
+
(about 10%))
209m
88
Ra = 117 μs (α (about 90%), β
+
(about 10%))
210
88
Ra = 4.0 s ()
210m
88
Ra = 2.32 μs (internal transition (100%))
211
88
Ra = 13.2 s (α (> 93%), β
+
(< 7%))
211m
88
Ra = 9.7 μs (internal transition (100%))
212
88
Ra = 13.0 s ()
212m
88
Ra = 10.5 μs (internal transition (100%))
212n
88
Ra = 850 ns (internal transition (100%))
213
88
Ra = 2.73 min (α (80%), β
+
)
213m
88
Ra = 2.20 ms (internal transition (about 99%), α (0.6%))
214
88
Ra = 2.437 s (α (about 100%), β
+
(0.059%))
214m
88
Ra = 118 ns (internal transition (100%))
214n
88
Ra = 67.3 μs (internal transition (about 100%), α (0.09%))
214p
88
Ra = 295 ns (internal transition (100%))
214q
88
Ra = 279 ns (internal transition (100%))
214r
88
Ra = 225 ns (internal transition (100%))
214x
88
Ra = 128 ns (internal transition (100%))
215
88
Ra = 1.67 ms (α (100%))
215m
88
Ra = 7.31 μs (internal transition (100%))
215n
88
Ra = 1.39 μs (internal transition (100%))
215p
88
Ra = 555 ns (internal transition (100%))
216
88
Ra = 182 ns (α (100%))
217
88
Ra = 1.63 μs (α (100%))
218
88
Ra = 25.2 μs (α (100%))
219
88
Ra = 10 ms (α (100%))
220
88
Ra = 17.9 ms (α (100%))
221
88
Ra = 28 s (α (100%), heavy cluster emission
14
C (1.2·10
-10
%))
222
88
Ra = 33.6 s (α (100%), heavy cluster emission
14
C (3.0·10
-8
%))
223
88
Ra = 11.4377 d (α (100%), heavy cluster emission
14
C (8.9·10
-8
%))
224
88
Ra = 3.6913 d (α (100%), heavy cluster emission
14
C (4.0·10
-9
%))
225
88
Ra = 14.9 d (β
-
(100%))
226
88
Ra = 1600 y (α (100%), heavy cluster emission
14
C (0.000 000 0026%))
227
88
Ra = 42.2 min (β
-
(100%))
228
88
Ra = 5.75 y (β
-
(100%))
229
88
Ra = 4.0 min (β
-
(100%))
230
88
Ra = 93 min (β
-
(100%))
231
88
Ra = 104 s (β
-
(100%))
232
88
Ra = 4.0 min (β
-
(100%))
233
88
Ra = 30 s (β
-
(100%))
234
88
Ra = 30 s (β
-
(100%))
Electrode potential:
Ra
2+
+ 2e
-
→ Ra, E = -2.8 V (water, 25°C)
Standard molar enthalpy (heat) of formation Δ
f
H
0
(298.15 K, kJ/mol):
0 (s)
Standard molar Gibbs energy of formation Δ
f
G
0
(298.15 K, kJ/mol):
0 (s)
Standard molar entropy S
0
(298.15 K, J/(mol·K)):
69.1 (s)
Molar heat capacity at constant pressure C
p
(298.15 K, J/(mol·K)):
29.3 (s)
Molar enthalpy (heat) of fusion Δ
fus
H (kJ/mol):
8
Enthalpy (heat) of vaporization Δ
vap
H (kJ/mol):
149.6
ΔH
sublimation
(kJ/mol):
157.9
Standard molar enthalpy (heat) of formation Δ
f
H
0
(298.15 K, kJ/mol):
162 (g)
Standard molar entropy S
0
(298.15 K, J/(mol·K)):
176.3 (g)
Molar heat capacity at constant pressure C
p
(298.15 K, J/(mol·K)):
20.786 (g)
References:
Бекман И.Н. Радиохимия. Том II: Радиоактивные элементы. - М.: Издатель Мархитин П.Ю., 2014. - pp. 94-107 [Russian]
Вдовенко В.М., Дубасов Ю.В. Аналитическая химия радия. - Л.: Наука, 1973. - pp. 24-25 [Russian]
Гурвич Я.А. Справочник молодого аппаратчика-химика. - М.: Химия, 1991. - pp. 51 [Russian]
Краткая химическая энциклопедия. - Т. 4: Пирометаллургия-С. - М.: Советская энциклопедия, 1965. - pp. 435-438 [Russian]
Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977. - pp. 91 [Russian]
Рипан Р., Четяну И. Неорганическая химия. - Т.1. - М.: Мир, 1971. - pp. 259-260 [Russian]
Химическая энциклопедия. - Т. 4. - М.: Советская энциклопедия, 1995. - pp. 153-154 [Russian]
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© Collected Ruslan Anatolievich Kiper, burewestnik@mail.ru
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