Introduction
Group: 1 or I A
Atomic Weight: 85.4678
Period: 5
CAS Number: 7440-17-7
Classification
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)
Description • Uses/Function
Discovered in 1861 by Bunsen and Kirchoff in the mineral lepidolite by use of the spectroscope. The element is much moreabundant than was thought several years ago. It is now considered to be the 16th most abundant element in the earth’s crust. Rubidium occurs inpollucite, carnallite, leucite, and zinnwaldite, which contains traces up to 1%, in the form of the oxide. It is found in lepidolite to the extent of about1.5%, and is recovered commercially from this source. Potassium minerals, such as those found at Searles Lake, California, and potassium chloriderecovered from brines in Michigan also contain the element and are commercial sources. It is also found along with cesium in the extensive depositsof pollucite at Bernic Lake, Manitoba. Rubidium can be liquid at room temperature. It is a soft, silvery-white metallic element of the alkali group andis the second most electropositive and alkaline element. It ignites spontaneously in air and reacts violently in water, setting fire to the liberated hydrogen.As with other alkali metals, it forms amalgams with mercury and it alloys with gold, cesium, sodium, and potassium. It colors a flame yellowish violet.Rubidium metal can be prepared by reducing rubidium chloride with calcium, and by a number of other methods. It must be kept under a dry mineraloil or in a vacuum or inert atmosphere. Thirty five isotopes and isomers of rubidium are known. Naturally occurring rubidium is made of two isotopes,85Rb and 87Rb. Rubidium-87 is present to the extent of 27.83% in natural rubidium and is a beta emitter with a half-life of 4.9 X 10^10 years. Ordinaryrubidium is sufficiently radioactive to expose a photographic film in about 30 to 60 days. Rubidium forms four oxides: Rb2O, Rb2O2, Rb2O3, Rb2O4.Because rubidium can be easily ionized, it has been considered for use in “ion engines” for space vehicles; however, cesium is somewhat more efficientfor this purpose. It is also proposed for use as a working fluid for vapor turbines and for use in a thermoelectric generator using the magnetohydrodynamicprinciple where rubidium ions are formed by heat at high temperature and passed through a magnetic field. These conduct electricity and actlike an armature of a generator thereby generating an electric current. Rubidium is used as a getter in vacuum tubes and as a photocell component. Ithas been used in making special glasses. RbAg4I5 is important, as it has the highest room conductivity of any known ionic crystal. At 20°C itsconductivity is about the same as dilute sulfuric acid. This suggests use in thin film batteries and other applications. The present cost in small quantitiesis about $20/g (99.8% pure). 1
Physical Properties
Melting Point:2* 39.30 °C = 312.45 K = 102.74 °F
Electron Configuration: [Kr] 5s1
n = 5
Electronegativity (Pauling scale):4 0.82
Specific Heat: 0.363 J/g°C 8 = 31.025 J/mol°C = 0.087 cal/g°C = 7.415 cal/mol°C
Earth - Source Compounds: halide salts or brines 14
External Links:
Journals:
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:26.
Boiling Point:2* 688 °C = 961.15 K = 1270.4 °F
Sublimation Point:2
Triple Point:2
Critical Point:2 1820 °C = 2093.15 K = 3308 °F 2
Density:3 1.53 g/cm3
* - at 1 atm
Electron Configuration
Block: s
Highest Occupied Energy Level: 5
Valence Electrons: 1
Quantum Numbers:
ℓ = 0
mℓ = 0
ms = +½
Bonding
Electropositivity (Pauling scale): 3.18
Electron Affinity:5 0.48592 eV
Oxidation States: +1
Work Function:6 2.20 eV = 3.5244E-19 J
Ionization Potential
eV 7
kJ/mol
1
4.17713
403.0
2
27.285
2632.6
3
40
3859.4
Ionization Potential
eV 7
kJ/mol
4
52.6
5075.1
5
71
6850.5
6
84.4
8143.4
Ionization Potential
eV 7
kJ/mol
7
99.2
9571.3
8
136
13122.0
9
150
14472.8
10
277.1
26736.1
Thermochemistry
Thermal Conductivity: 58.2 (W/m)/K, 27°C 9
Heat of Fusion: 2.192 kJ/mol 10 = 25.6 J/g
Heat of Vaporization: 72.216 kJ/mol 11 = 844.9 J/g
State of Matter
Enthalpy of Formation (ΔHf°)12
Entropy (S°)12
Gibbs Free Energy (ΔGf°)12
(kcal/mol)
(kJ/mol)
(cal/K)
(J/K)
(kcal/mol)
(kJ/mol)
(g)
20.51
85.81384
40.63
169.99592
13.35
55.8564
(s)
0
0
16.6
69.4544
0
0
Isotopes
Nuclide
Mass 13
Half-Life 13
Nuclear Spin 13
Binding Energy
100Rb
99.94987(32)#
51(8) ms
(3+)
825.69 MeV
101Rb
100.95320(18)
32(5) ms
(3/2+)#
832.83 MeV
102Rb
101.95887(54)#
37(5) ms
840.90 MeV
71Rb
70.96532(54)#
5/2-#
576.72 MeV
72Rb
71.95908(54)#
<1.5 μs
3+#
590.38 MeV
73Rb
72.95056(16)#
<30 ns
3/2-#
606.83 MeV
74Rb
73.944265(4)
64.76(3) ms
(0+)
620.49 MeV
75Rb
74.938570(8)
19.0(12) s
(3/2-)
634.15 MeV
76Rb
75.9350722(20)
36.5(6) s
1(-)
645.02 MeV
77Rb
76.930408(8)
3.77(4) min
3/2-
657.75 MeV
78Rb
77.928141(8)
17.66(8) min
0(+)
667.68 MeV
79Rb
78.923989(6)
22.9(5) min
5/2+
680.41 MeV
80Rb
79.922519(7)
33.4(7) s
1+
689.41 MeV
81Rb
80.918996(6)
4.570(4) h
3/2-
701.21 MeV
82Rb
81.9182086(30)
1.273(2) min
1+
709.28 MeV
83Rb
82.915110(6)
86.2(1) d
5/2-
720.15 MeV
84Rb
83.914385(3)
33.1(1) d
2-
729.15 MeV
85Rb
84.911789738(12)
STABLE
5/2-
740.02 MeV
86Rb
85.91116742(21)
18.642(18) d
2-
748.09 MeV
87Rb
86.909180527(13)
4.923(22)E+10 a
3/2-
758.02 MeV
88Rb
87.91131559(17)
17.773(11) min
2-
764.23 MeV
89Rb
88.912278(6)
15.15(12) min
3/2-
771.37 MeV
90Rb
89.914802(7)
158(5) s
0-
777.58 MeV
91Rb
90.916537(9)
58.4(4) s
3/2(-)
783.79 MeV
92Rb
91.919729(7)
4.492(20) s
0-
789.06 MeV
93Rb
92.922042(8)
5.84(2) s
5/2-
794.34 MeV
94Rb
93.926405(9)
2.702(5) s
3(-)
798.69 MeV
95Rb
94.929303(23)
377.5(8) ms
5/2-
803.96 MeV
96Rb
95.93427(3)
202.8(33) ms
2+
807.38 MeV
97Rb
96.93735(3)
169.9(7) ms
3/2+
812.65 MeV
98Rb
97.94179(5)
114(5) ms
(0,1)(-#)
817.00 MeV
99Rb
98.94538(13)
50.3(7) ms
(5/2+)
821.34 MeV
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 13
Abundance
Earth - Seawater: 0.12 mg/L 15
Earth -
Crust:
90 mg/kg = 0.009% 15
Earth -
Total:
458 ppb 16
Mercury -
Total:
75 ppb 16
Venus -
Total:
509 ppb 16
Chondrites - Total: ~5 (relative to 106 atoms of Si) 17
Human Body - Total: 0.00046% 18
Compounds
rubidium acetylacetonate
rubidium bromide
rubidium chloride
rubidium chromate
rubidium fluoride
rubidium hydride
Safety Information
Material Safety Data Sheet - ACI Alloys, Inc.
For More Information
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
(1) John C. Payne and John E. Dunley, J. N. Am. Benthol. Soc. 21, 715-727 (2002)
(2) Sheldon Breiner, Science 150, 185-193 (1965)
(3) Rae Ehrman Drazin and Robert I. Lehrer, J. Infect. Dis. 134, 238-244 (1976)
Sources
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(4) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(6) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(12) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(13) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(14) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(15) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(16) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(17) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.
(18) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 7:17.