Strontium

Strontium (Sr)

Soft yellowish metallic element, belongs to group 2 of the periodic table. Highly reactive chemically. Sr-90 is present in radioactive fallout and has a half-life of 28 years. Discovered in 1798 by Klaproth and Hope, isolated in 1808 by Humphry Davy.
Atomic Number38
Atomic Weight87.62
Mass Number88
Group2
Period5
Blocks
Protons38 p+
Neutrons50 n0
Electrons38 e-
Strontium destilled crystals.jpg Animated Bohr Model of Sr (Strontium) Enhanced Bohr Model of Sr (Strontium) Bohr Model: Sr (Strontium) Orbital Diagram of Sr (Strontium)

Properties

Atomic Radius
200 pm
Molar Volume
Covalent Radius
185 pm
Metallic Radius
191 pm
Ionic Radius
118 pm
Crystal Radius
132 pm
Van der Waals Radius
249 pm
Density
2.64 g/cm³
Energy
Proton Affinity
Electron Affinity
Ionization Energy
5.6948672 eV/particle
Heat of Vaporization
144 kJ/mol
Heat of Fusion
9.2 kJ/mol
Heat of Formation
164 kJ/mol
Electrons
Electron Shells2, 8, 18, 8, 2
Valence Electrons2
Electron Configuration[Kr] 5s2
Oxidation States1, 2
Electronegativity
0.95
Electrophilicity
0.730062406922635 eV/particle
Phases
PhaseSolid
Gas Phase
Boiling Point
1,650.15 K
Melting Point
1,050.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color
Silver
Appearance
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
0.0000225 1/K
Molar Heat Capacity
26.79 J/(mol K)
Specific Heat Capacity
0.306 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
TypeConductor
Electrical Conductivity
7.7 MS/m
Electrical Resistivity
0.00000013 m Ω
Superconducting Point
Magnetism
Typeparamagnetic
Magnetic Susceptibility (Mass)
0.00000000132 m³/Kg
Magnetic Susceptibility (Molar)
0.000000000116 m³/mol
Magnetic Susceptibility (Volume)
0.00000347
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal StructureFace Centered Cubic (FCC)
Lattice Constant
6.08 Å
Lattice Anglesπ/2, π/2, π/2
Mechanical Properties
Hardness
1.5 MPa
Bulk Modulus
Shear Modulus
6.1 GPa
Young Modulus
Poisson Ratio
0.28
Speed of Sound
Classification
CategoryAlkaline earth metals, Alkaline earth metals
CAS GroupIIA
IUPAC GroupIIA
Glawe Number15
Mendeleev Number8
Pettifor Number15
Geochemical Classalkaline earth metal
Goldschmidt Classlitophile
Other
Gas Basicity
Dipole Polarizability
197.2 ± 0.2 a₀
C6 Dispersion Coefficient
3,175 a₀
Allotropes
Neutron Cross Section
1.2
Neutron Mass Absorption
0.0005
Quantum Numbers1S0
Space Group225 (Fm_3m)

Isotopes of Strontium

Stable Isotopes4
Unstable Isotopes31
Radioactive Isotopes31

73Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
72.9657 ± 0.00043 Da
Mass Number73
G-Factor
Half Life
25.3 ± 1.4 ms
Spin5/2
Quadrupole Moment
Discovery Year1993
Parity-

73Sr Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)63%

74Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
73.95617 ± 0.000107 Da
Mass Number74
G-Factor
0
Half Life
27.6 ± 2.6 ms
Spin0
Quadrupole Moment
0
Discovery Year1995
Parity+

74Sr Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)%

75Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
74.949952767 ± 0.000236183 Da
Mass Number75
G-Factor
Half Life
85.2 ± 2.3 ms
Spin3/2
Quadrupole Moment
Discovery Year1991
Parity-

75Sr Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)5.2%

76Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
75.94176276 ± 0.000037 Da
Mass Number76
G-Factor
0
Half Life
7.89 ± 0.07 s
Spin0
Quadrupole Moment
0
Discovery Year1990
Parity+

76Sr Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)3.4%

77Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
76.937945454 ± 0.0000085 Da
Mass Number77
G-Factor
-0.1392 ± 0.0016
Half Life
9 ± 0.2 s
Spin5/2
Quadrupole Moment
1.27 ± 0.05
Discovery Year1976
Parity+

77Sr Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%
β+ p (β+-delayed proton emission)0.08%

78Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
77.932179979 ± 0.000008 Da
Mass Number78
G-Factor
0
Half Life
156.1 ± 2.7 s
Spin0
Quadrupole Moment
0
Discovery Year1982
Parity+

78Sr Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

79Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
78.929704692 ± 0.000007967 Da
Mass Number79
G-Factor
-0.316 ± 0.0026666666666667
Half Life
2.25 ± 0.1 m
Spin3/2
Quadrupole Moment
0.661 ± 0.006
Discovery Year1972
Parity-

79Sr Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

80Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
79.924517538 ± 0.000003718 Da
Mass Number80
G-Factor
0
Half Life
106.3 ± 1.5 m
Spin0
Quadrupole Moment
0
Discovery Year1961
Parity+

80Sr Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

81Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
80.923211393 ± 0.000003358 Da
Mass Number81
G-Factor
1.086 ± 0.008
Half Life
22.3 ± 0.4 m
Spin1/2
Quadrupole Moment
0
Discovery Year1952
Parity-

81Sr Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

82Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
81.918399845 ± 0.000006432 Da
Mass Number82
G-Factor
0
Half Life
25.35 ± 0.03 d
Spin0
Quadrupole Moment
0
Discovery Year1952
Parity+

82Sr Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%

83Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
82.917554372 ± 0.000007336 Da
Mass Number83
G-Factor
-0.237 ± 0.0002
Half Life
32.41 ± 0.03 h
Spin7/2
Quadrupole Moment
0.708 ± 0.011
Discovery Year1952
Parity+

83Sr Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)100%

84Sr

Abundance
0.56 ± 0.02
Relative Atomic Mass
83.913419118 ± 0.000001334 Da
Mass Number84
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1936
Parity+

84Sr Decay Modes
Decay ModeIntensity
+ (double β+ decay)%

85Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
84.912932041 ± 0.00000302 Da
Mass Number85
G-Factor
-0.22224444444444 ± 0.00015555555555556
Half Life
64.846 ± 0.006 d
Spin9/2
Quadrupole Moment
0.263 ± 0.014
Discovery Year1940
Parity+

85Sr Decay Modes
Decay ModeIntensity
ϵ (electron capture)100%

86Sr

Abundance
9.86 ± 0.2
Relative Atomic Mass
85.90926072473 ± 0.00000000563 Da
Mass Number86
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1931
Parity+

87Sr

Abundance
7 ± 0.2
Relative Atomic Mass
86.90887749454 ± 0.0000000055 Da
Mass Number87
G-Factor
-0.24292444444444 ± 0.000024444444444444
Half Life
Spin9/2
Quadrupole Moment
0.305 ± 0.002
Discovery Year1931
Parity+

88Sr

Abundance
82.58 ± 0.35
Relative Atomic Mass
87.905612253 ± 0.000000006 Da
Mass Number88
G-Factor
0
Half Life
Spin0
Quadrupole Moment
0
Discovery Year1923
Parity+

89Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
88.907450808 ± 0.000000098 Da
Mass Number89
G-Factor
-0.4592 ± 0.0008
Half Life
50.563 ± 0.025 d
Spin5/2
Quadrupole Moment
-0.253 ± 0.008
Discovery Year1937
Parity+

89Sr Decay Modes
Decay ModeIntensity
β (β decay)100%

90Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
89.90772787 ± 0.000001555 Da
Mass Number90
G-Factor
0
Half Life
28.91 ± 0.03 y
Spin0
Quadrupole Moment
0
Discovery Year1948
Parity+

90Sr Decay Modes
Decay ModeIntensity
β (β decay)100%

91Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
90.910195942 ± 0.000005853 Da
Mass Number91
G-Factor
-0.354 ± 0.0008
Half Life
9.65 ± 0.06 h
Spin5/2
Quadrupole Moment
0.042 ± 0.01
Discovery Year1943
Parity+

91Sr Decay Modes
Decay ModeIntensity
β (β decay)100%

92Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
91.911038222 ± 0.000003675 Da
Mass Number92
G-Factor
0
Half Life
2.611 ± 0.017 h
Spin0
Quadrupole Moment
0
Discovery Year1956
Parity+

92Sr Decay Modes
Decay ModeIntensity
β (β decay)100%

93Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
92.914024314 ± 0.000008109 Da
Mass Number93
G-Factor
-0.3172 ± 0.0008
Half Life
7.43 ± 0.03 m
Spin5/2
Quadrupole Moment
0.24 ± 0.01
Discovery Year1959
Parity+

93Sr Decay Modes
Decay ModeIntensity
β (β decay)100%

94Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
93.915355641 ± 0.000001785 Da
Mass Number94
G-Factor
0
Half Life
75.3 ± 0.2 s
Spin0
Quadrupole Moment
0
Discovery Year1959
Parity+

94Sr Decay Modes
Decay ModeIntensity
β (β decay)100%

95Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
94.919358282 ± 0.000006237 Da
Mass Number95
G-Factor
-1.074 ± 0.004
Half Life
23.9 ± 0.14 s
Spin1/2
Quadrupole Moment
0
Discovery Year1961
Parity+

95Sr Decay Modes
Decay ModeIntensity
β (β decay)100%

96Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
95.921719045 ± 0.000009089 Da
Mass Number96
G-Factor
0
Half Life
1.059 ± 0.008 s
Spin0
Quadrupole Moment
0
Discovery Year1971
Parity+

96Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%

97Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
96.926375621 ± 0.000003633 Da
Mass Number97
G-Factor
-0.996 ± 0.004
Half Life
432 ± 4 ms
Spin1/2
Quadrupole Moment
0
Discovery Year1978
Parity+

97Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)0.02%

98Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
97.928692636 ± 0.000003463 Da
Mass Number98
G-Factor
0
Half Life
653 ± 2 ms
Spin0
Quadrupole Moment
0
Discovery Year1971
Parity+

98Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)0.23%

99Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
98.932883604 ± 0.000005085 Da
Mass Number99
G-Factor
-0.174 ± 0.0033333333333333
Half Life
269.2 ± 1 ms
Spin3/2
Quadrupole Moment
0.76 ± 0.04
Discovery Year1975
Parity+

99Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)0.1%

100Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
99.93578327 ± 0.000007426 Da
Mass Number100
G-Factor
0
Half Life
202.1 ± 1.7 ms
Spin0
Quadrupole Moment
0
Discovery Year1978
Parity+

100Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)1.11%

101Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
100.940606264 ± 0.000009103 Da
Mass Number101
G-Factor
Half Life
113.7 ± 1.7 ms
Spin5/2
Quadrupole Moment
Discovery Year1983
Parity-

101Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)2.75%

102Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
101.944004679 ± 0.000072 Da
Mass Number102
G-Factor
0
Half Life
69 ± 6 ms
Spin0
Quadrupole Moment
0
Discovery Year1986
Parity+

102Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)5.5%

103Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
102.949243 ± 0.000215 Da
Mass Number103
G-Factor
Half Life
53 ± 10 ms
Spin5/2
Quadrupole Moment
Discovery Year1997
Parity+

103Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

104Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
103.953022 ± 0.000322 Da
Mass Number104
G-Factor
0
Half Life
50.6 ± 4.2 ms
Spin0
Quadrupole Moment
0
Discovery Year1997
Parity+

104Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

105Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
104.959001 ± 0.000537 Da
Mass Number105
G-Factor
Half Life
39 ± 5 ms
Spin5/2
Quadrupole Moment
Discovery Year1997
Parity+

105Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

106Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
105.963177 ± 0.000644 Da
Mass Number106
G-Factor
0
Half Life
21 ± 8 ms
Spin0
Quadrupole Moment
0
Discovery Year2010
Parity+

106Sr Decay Modes
Decay ModeIntensity
β (β decay)100%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

107Sr

AbundanceRadioactive ☢️
Relative Atomic Mass
106.969672 ± 0.000751 Da
Mass Number107
G-Factor
Half Life
Spin1/2
Quadrupole Moment
0
Discovery Year2010
Parity+

107Sr Decay Modes
Decay ModeIntensity
β (β decay)%
β n (β-delayed neutron emission)%
2n (2-neutron emission)%

History

Strontium was recognized as a new element in 1790 when Adair Crawford and his colleague William Cruickshank analyzed a mineral sample from a lead mine near Strontian, Scotland. The element was eventually isolated by Sir Humphry Davy in 1808. The isolation was done by the electrolysis of a mixture containing strontium chloride and mercuric oxide. Named after Strontian, a town in Scotland

DiscoverersA. Crawford
Discovery LocationScotland
Discovery Year1790
Etymology (Name Origin)From the Scottish town, Strontian.
PronunciationSTRON-she-em (English)
Strontium's non-radioactive isotopes are considered non-toxic
Strontium metal turns yellow when exposed to air

Uses

The primary use for strontium is in glass for color television cathode ray tubes. Strontium salts are used in flares and fireworks for a crimson color. Strontium chloride is used in toothpaste for sensitive teeth. Strontium oxide is used to improve the quality of pottery glazes. Used in flares and fireworks for crimson color. Strontium-90 is a long lived highly radioactive fallout product of atomic-bomb explosions.

Sources

Found in minerals celestite and strontianite.

Abundance
Abundance in Earth's crust
370 mg/kg
Abundance in Oceans
7.9 mg/L
Abundance in Human Body
0.00046 %
Abundance in Meteor
0.00087 %
Abundance in Sun
0.000005 %
Abundance in Universe
0.000004 %

Nuclear Screening Constants

1s0.8089
2p3.9696
2s10.0982
3d15.2738
3p15.8324
3s15.3362
4p26.068
4s24.5556
5s31.9295