Introduction
Group: 2 or II A
Atomic Weight: 87.62
Period: 5
CAS Number: 7440-24-6
Classification
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)
Description • Uses/Function
Isolated by Davey by electrolysis in 1808; however, Adair Crawford in 1790 recognized a new mineral (strontianite) as differing from other barium minerals (baryta).Strontium is found chiefly as celestite (SrSO4) and strontianite (SrCO3). The metal can be prepared by electrolysis of the fused chloride mixed withpotassium chloride, or is made by reducing strontium oxide with aluminum in a vacuum at a temperature at which strontium distills off. Three allotropicforms of the metal exist, with transition points at 235 and 540°C. Strontium is softer than calcium and decomposes water more vigorously. It does notabsorb nitrogen below 380°C. It should be kept under mineral oil to prevent oxidation. Freshly cut strontium has a silvery appearance, but rapidly turnsa yellowish color with the formation of the oxide. The finely divided metal ignites spontaneously in air. Volatile strontium salts impart a beautifulcrimson color to flames, and these salts are used in pyrotechnics and in the production of flares. Natural strontium is a mixture of four stable isotopes.Twenty six other unstable isotopes and isomers are known to exist. Of greatest importance is 90Sr with a half-life of 29 years. It is a product of nuclearfallout and presents a health problem. This isotope is one of the best long-lived high-energy beta emitters known, and is used in SNAP (Systems forNuclear Auxiliary Power) devices. These devices hold promise for use in space vehicles, remote weather stations, navigational buoys, etc., where alightweight, long-lived, nuclear-electric power source is needed. The major use for strontium at present is in producing glass for color television picturetubes. It has also found use in producing ferrite magnets and in refining zinc. Strontium titanate is an interesting optical material as it has an extremelyhigh refractive index and an optical dispersion greater than that of diamond. It has been used as a gemstone, but it is very soft. It does not occur naturally.Strontium metal (99% pure) costs about $1/g while the metal, 99.95% pure, sells for about $10/g. 1
• "used in fireworks and flares, which show the characteristic red glow of strontium in a flame." 2
Physical Properties
Melting Point:3* 777 °C = 1050.15 K = 1430.6 °F
Electron Configuration: [Kr] 5s2
n = 5
Electronegativity (Pauling scale):5 0.95
Specific Heat: 0.301 J/g°C 9 = 26.374 J/mol°C = 0.072 cal/g°C = 6.303 cal/mol°C
Earth - Source Compounds: carbonates/sulfates 15
External Links:
Journals:
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:29-4:30.
Boiling Point:3* 1382 °C = 1655.15 K = 2519.6 °F
Sublimation Point:3
Triple Point:3
Critical Point:3
Density:4 2.64 g/cm3
* - at 1 atm
Electron Configuration
Block: s
Highest Occupied Energy Level: 5
Valence Electrons: 2
Quantum Numbers:
ℓ = 0
mℓ = 0
ms = -½
Bonding
Electropositivity (Pauling scale): 3.05
Electron Affinity:6 0.048 eV
Oxidation States: +2
Work Function:7 2.76 eV = 4.42152E-19 J
Ionization Potential
eV 8
kJ/mol
1
5.6949
549.5
2
11.03013
1064.2
3
42.89
4138.3
Ionization Potential
eV 8
kJ/mol
4
57
5499.7
5
71.6
6908.3
6
90.8
8760.9
7
106
10227.4
Ionization Potential
eV 8
kJ/mol
8
122.3
11800.2
9
162
15630.6
10
177
17077.9
11
324.1
31270.9
Thermochemistry
Thermal Conductivity: 35.3 (W/m)/K, 27°C 10
Heat of Fusion: 8.3 kJ/mol 11 = 94.7 J/g
Heat of Vaporization: 144 kJ/mol 12 = 1643.5 J/g
State of Matter
Enthalpy of Formation (ΔHf°)13
Entropy (S°)13
Gibbs Free Energy (ΔGf°)13
(kcal/mol)
(kJ/mol)
(cal/K)
(J/K)
(kcal/mol)
(kJ/mol)
(s)
0
0
12.5
52.3
0
0
(ℓ)
1.82
7.61488
13.66
57.15344
1.47
6.15048
(g)
39.2
164.0128
39.32
164.51488
31.2
130.5408
Isotopes
Nuclide
Mass 14
Half-Life 14
Nuclear Spin 14
Binding Energy
100Sr
99.93535(14)
202(3) ms
0+
837.95 MeV
101Sr
100.94052(13)
118(3) ms
(5/2-)
841.36 MeV
102Sr
101.94302(12)
69(6) ms
0+
849.43 MeV
103Sr
102.94895(54)#
50# ms [>300 ns]
857.51 MeV
104Sr
103.95233(75)#
30# ms [>300 ns]
0+
856.26 MeV
105Sr
104.95858(75)#
20# ms [>300 ns]
864.33 MeV
73Sr
72.96597(64)#
>25 ms
1/2-#
592.08 MeV
74Sr
73.95631(54)#
50# ms [>1.5 μs]
0+
608.53 MeV
75Sr
74.94995(24)
88(3) ms
(3/2-)
623.12 MeV
76Sr
75.94177(4)
7.89(7) s
0+
638.65 MeV
77Sr
76.937945(10)
9.0(2) s
5/2+
650.45 MeV
78Sr
77.932180(8)
159(8) s
0+
663.17 MeV
79Sr
78.929708(9)
2.25(10) min
3/2(-)
674.04 MeV
80Sr
79.924521(7)
106.3(15) min
0+
686.77 MeV
81Sr
80.923212(7)
22.3(4) min
1/2-
695.77 MeV
82Sr
81.918402(6)
25.36(3) d
0+
708.50 MeV
83Sr
82.917557(11)
32.41(3) h
7/2+
717.50 MeV
84Sr
83.913425(3)
STABLE
0+
729.30 MeV
85Sr
84.912933(3)
64.853(8) d
9/2+
738.30 MeV
86Sr
85.9092602(12)
STABLE
0+
749.17 MeV
87Sr
86.9088771(12)
STABLE
9/2+
758.17 MeV
88Sr
87.9056121(12)
STABLE
0+
769.04 MeV
89Sr
88.9074507(12)
50.57(3) d
5/2+
775.25 MeV
90Sr
89.907738(3)
28.90(3) a
0+
783.32 MeV
91Sr
90.910203(5)
9.63(5) h
5/2+
788.59 MeV
92Sr
91.911038(4)
2.66(4) h
0+
795.73 MeV
93Sr
92.914026(8)
7.423(24) min
5/2+
801.01 MeV
94Sr
93.915361(8)
75.3(2) s
0+
808.15 MeV
95Sr
94.919359(8)
23.90(14) s
1/2+
812.50 MeV
96Sr
95.921697(29)
1.07(1) s
0+
818.70 MeV
97Sr
96.926153(21)
429(5) ms
1/2+
822.12 MeV
98Sr
97.928453(28)
0.653(2) s
0+
828.33 MeV
99Sr
98.93324(9)
0.269(1) s
3/2+
831.74 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. 14
Abundance
Earth - Seawater: 7.2 mg/L 16
Earth -
Crust:
370 mg/kg = 0.037% 16
Earth -
Total:
14.5 ppm 17
Mercury -
Total:
1.11 ppm 17
Venus -
Total:
15.2 ppm 17
Chondrites - Total: 20 (relative to 106 atoms of Si) 18
Human Body - Total: 0.00046% 19
Compounds
strontium aluminate
strontium boride
strontium bromide
strontium bromide hexahydrate
strontium carbonate
strontium chloride
strontium chloride dihydrate
strontium chloride hexahydrate
strontium chromate
strontium dithionate
Safety Information
Material Safety Data Sheet - ACI Alloys, Inc.
For More Information
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
(1) Vaughan T. Bowen and T. T. Sugihara, Proc. Nat. Acad. Sci. U.S.A. 43, 576-580 (1957)
(2) Dasch, Hills and Turekian, Science 153, 295-297 (1966)
(3) A. R. Johnson, W. D. Armstrong and Leon Singer, Science 153, 1396-1397 (1966)
Sources
(2) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 931.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(5) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(7) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(13) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(14) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(15) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(16) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(17) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(18) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.
(19) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 7:17.