Cesium (Cs)

Cesium is the 55th element in the periodic table and has a symbol of Cs and atomic number of 55. It has an atomic weight of 132.90545 and a mass number of 133. Cesium has fifty-five protons and seventy-eight neutrons in its nucleus, and fifty-five electrons in six shells. It is located in group one, period six and block s of the periodic table. Soft silvery-white metallic element belonging to group 1 of the periodic table. One of the three metals which are liquid at room temperature. Cs-133 is the natural, and only stable, isotope. Fifteen other radioisotopes exist. Caesium reacts explosively with cold water, and ice at temperatures above 157K. Caesium hydroxide is the strongest base known. Caesium is the most electropositive, most alkaline and has the least ionization potential of all the elements. Known uses include the basis of atomic clocks, catalyst for the hydrogenation of some organic compounds, and in photoelectric cells. Caesium was discovered by Gustav Kirchoff and Robert Bunsen in Germany in 1860 spectroscopically. Its identification was based upon the bright blue lines in its spectrum. The name comes from the latin word caesius, which means sky blue. Caesium should be considered highly toxic. Some of the radioisotopes are even more toxic.

Atomic Number	55
Atomic Weight	132.90545196
Mass Number	133

Group	1
Period	6
Block	s

Protons	55 p⁺
Neutrons	78 n⁰
Electrons	55 e^-

Properties

Physical Properties
Atomic Radius	260 pm 249 pm
Molar Volume	70 cm³/mol
Covalent Radius	232 pm 209 pm 237 pm 244 pm
Metallic Radius	235 pm 267 pm
Ionic Radius	167 pm 174 pm 178 pm 181 pm 185 pm 188 pm
Crystal Radius	181 pm 188 pm 192 pm 195 pm 199 pm 202 pm
Van der Waals Radius	300 pm 343 pm 344 pm 343 pm 451.7 pm
Density	1.873 g/cm³ 1,843 kg/m³
Energy
Proton Affinity
Electron Affinity	0.471626 eV/particle
Ionization Energy	3.893905548 eV/particle 23.15745 eV/particle 33.195 eV/particle 43 eV/particle 56 eV/particle 69.1 eV/particle 82.9 eV/particle 110.09 eV/particle 125.61 eV/particle 213.3 eV/particle 233 eV/particle 261 eV/particle 289 eV/particle 316 eV/particle 352 eV/particle 382 eV/particle 413 eV/particle 445 eV/particle 476 eV/particle 597 eV/particle 629 eV/particle 666 eV/particle 700 eV/particle 753 eV/particle 791 eV/particle 875 eV/particle 916.07 eV/particle 1,592 eV/particle 1,672 eV/particle 1,757 eV/particle 1,848 eV/particle 1,936 eV/particle 2,029 eV/particle 2,137 eV/particle 2,230 eV/particle 2,329 eV/particle 2,422 eV/particle 2,683 eV/particle 2,767 eV/particle 2,859 eV/particle 2,945 eV/particle 3,118 eV/particle 3,214 eV/particle 3,392 eV/particle 3,485 eV/particle 7,989 eV/particle 8,224 eV/particle 8,484 eV/particle 8,726 eV/particle 9,350 eV/particle 9,629 eV/particle 9,974 eV/particle 10,208.78 eV/particle 41,861.073 eV/particle 42,912.99 eV/particle

Heat of Vaporization	68.3 kJ/mol
Heat of Fusion	2.09 kJ/mol
Heat of Formation	76.5 kJ/mol
Electrons
Electron Shells	2, 8, 18, 18, 8, 1

Valence Electrons	1

Electron Configuration	[Xe] 6s¹

Oxidation States	-1, 1
Electronegativity	3.898 eV/particle 0.1542125 0.79
Electrophilicity	0.696095447101947 eV/particle
Phases
Phase	Solid
Gas Phase
Boiling Point	944.15 K
Melting Point	301.65 K
Critical Pressure	9.4 MPa
Critical Temperature	1,938.15 K
Triple Point
Visual
Cesium is a Silver. Cs has a CPK of #ff1493, Jmol of #57178f, and MOLCAS GV of #57178f. The Appearance of Element 55 is silvery gold.
Color	Silver #ff1493 #57178f #57178f
Appearance	silvery gold
Refractive Index
Thermodynamic Properties
Thermal Conductivity	35.9 W/(m K)
Thermal Expansion
Molar Heat Capacity	32.21 J/(mol K)
Specific Heat Capacity	0.242 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type	Conductor
Electrical Conductivity	5 MS/m
Electrical Resistivity	0.0000002 m Ω
Superconducting Point
Magnetism
Type	paramagnetic
Magnetic Susceptibility (Mass)	0.0000000028 m³/Kg
Magnetic Susceptibility (Molar)	0.000000000372 m³/mol
Magnetic Susceptibility (Volume)	0.00000526
Magnetic Ordering
Curie Point
Neel Point
Structure
The Crystal Structure of Cesium is BCC. The lattice constant of Cs is 6.05 Å. The lattice angles of Element 55 are π/2, π/2, π/2.
Crystal Structure	Body Centered Cubic (BCC)
Lattice Constant	6.05 Å
Lattice Angles	π/2, π/2, π/2
Mechanical Properties
Cesium has a Brinell of 0.14 MPa, and Mohs hardness of 0.2 MPa. The Bulk Modulus of Cs is 1.6 GPa. The Young Modulus of Element 55 is 1.7 GPa.
Hardness	0.14 MPa 0.2 MPa
Bulk Modulus	1.6 GPa
Shear Modulus
Young Modulus	1.7 GPa
Poisson Ratio
Speed of Sound
Classification
The CAS Group of Cesium is IA. The IUPAC Group of Cs is IA. The Glawe Number of Element 55 is 8. The Mendeleev Number of Cesium (Cs) is 5. The Pettifor Number of Cesium is 8. The Geochemical Class of Cs is alkali metal. The Goldschmidt Class of Element 55 is litophile.
Category	Alkali metals, Alkali metals
CAS Group	IA
IUPAC Group	IA
Glawe Number	8
Mendeleev Number	5
Pettifor Number	8
Geochemical Class	alkali metal
Goldschmidt Class	litophile
Other
The Dipole Polarizability of Cesium is 400.9 plus or minus 0.7 a₀. Cs has a C6 Dispersion Coefficient (GB) of 6660 a₀. The Allotropes of Element 55 is . The Neutron Cross Section of Cesium (Cs) is 29. The Neutron Mass Absorption of Cesium is 0.0077. The Quantum Numbers of Cs is 2S1/2. The Space Group of Element 55 is 229 (Im_3m).
Gas Basicity
Dipole Polarizability	400.9 ± 0.7 a₀
C6 Dispersion Coefficient	6,660 a₀
Allotropes
Neutron Cross Section	29
Neutron Mass Absorption	0.0077
Quantum Numbers	2S1/2
Space Group	229 (Im_3m)

Isotopes of Cesium

Stable Isotopes	1
Unstable Isotopes	41
Radioactive Isotopes	41

¹¹¹Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	110.953945 ± 0.000215 Da
Mass Number	111
G-Factor
Half Life
Spin	3/2
Quadrupole Moment
Discovery Year
Parity	+

¹¹¹Cs Decay Modes

Decay Mode	Intensity
p (proton emission)	%

¹¹²Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	111.950172 ± 0.000124 Da
Mass Number	112
G-Factor
Half Life	490 ± 30 us
Spin	1
Quadrupole Moment
Discovery Year	1994
Parity	+

¹¹²Cs Decay Modes

Decay Mode	Intensity
p (proton emission)	100%
α (α emission)	0.26%

¹¹³Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	112.944428484 ± 0.000009207 Da
Mass Number	113
G-Factor
Half Life	16.94 ± 0.09 us
Spin	3/2
Quadrupole Moment
Discovery Year	1984
Parity	+

¹¹³Cs Decay Modes

Decay Mode	Intensity
p (proton emission)	100%

¹¹⁴Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	113.941292244 ± 0.000091323 Da
Mass Number	114
G-Factor
Half Life	570 ± 20 ms
Spin	1
Quadrupole Moment
Discovery Year	1978
Parity	+

¹¹⁴Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
α (α emission)	0.018%
β⁺ p (β⁺-delayed proton emission)	8.7%
β⁺α (β⁺-delayed α emission)	0.19%

¹¹⁵Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	114.93591 ± 0.00011 Da
Mass Number	115
G-Factor
Half Life	1.4 ± 0.8 s
Spin	9/2
Quadrupole Moment
Discovery Year	1978
Parity	+

¹¹⁵Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	0.07%

¹¹⁶Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	115.933395 ± 0.000108 Da
Mass Number	116
G-Factor
Half Life	700 ± 40 ms
Spin	1
Quadrupole Moment
Discovery Year	1975
Parity	+

¹¹⁶Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	0.28%
β⁺α (β⁺-delayed α emission)	0.049%

¹¹⁷Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	116.928616723 ± 0.000067 Da
Mass Number	117
G-Factor
Half Life	8.4 ± 0.6 s
Spin	9/2
Quadrupole Moment
Discovery Year	1972
Parity	+

¹¹⁷Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹¹⁸Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	117.926559517 ± 0.00001369 Da
Mass Number	118
G-Factor	1.935 ± 0.0025
Half Life	14 ± 2 s
Spin	2
Quadrupole Moment	1.31 ± 0.17
Discovery Year	1969
Parity	+

¹¹⁸Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺ p (β⁺-delayed proton emission)	0.021%
β⁺α (β⁺-delayed α emission)	0.0012%

¹¹⁹Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	118.922377327 ± 0.000014965 Da
Mass Number	119
G-Factor	1.2111111111111 ± 0.0066666666666667
Half Life	43 ± 0.2 s
Spin	9/2
Quadrupole Moment	2.65 ± 0.17
Discovery Year	1969
Parity	+

¹¹⁹Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺α (β⁺-delayed α emission)	2%

¹²⁰Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	119.920677277 ± 0.000010702 Da
Mass Number	120
G-Factor	1.93 ± 0.01
Half Life	60.4 ± 0.6 s
Spin	2
Quadrupole Moment	1.36 ± 0.07
Discovery Year	1969
Parity	+

¹²⁰Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺α (β⁺-delayed α emission)	2%
β⁺ p (β⁺-delayed proton emission)	7%

¹²¹Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	120.917227235 ± 0.00001534 Da
Mass Number	121
G-Factor	0.51266666666667 ± 0.0026666666666667
Half Life	155 ± 4 s
Spin	3/2
Quadrupole Moment	0.79 ± 0.04
Discovery Year	1969
Parity	+

¹²¹Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹²²Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	121.916108144 ± 0.000036164 Da
Mass Number	122
G-Factor	0.133 ± 0.002
Half Life	21.18 ± 0.19 s
Spin	1
Quadrupole Moment	-0.179 ± 0.01
Discovery Year	1969
Parity	+

¹²²Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
β⁺α (β⁺-delayed α emission)	2%

¹²³Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	122.91299606 ± 0.000013 Da
Mass Number	123
G-Factor	2.75 ± 0.014
Half Life	5.88 ± 0.03 m
Spin	1/2
Quadrupole Moment	0
Discovery Year	1954
Parity	+

¹²³Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹²⁴Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	123.912247366 ± 0.000009823 Da
Mass Number	124
G-Factor	0.672 ± 0.003
Half Life	30.9 ± 0.4 s
Spin	1
Quadrupole Moment	-0.69 ± 0.04
Discovery Year	1969
Parity	+

¹²⁴Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹²⁵Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	124.909725953 ± 0.000008304 Da
Mass Number	125
G-Factor	2.814 ± 0.014
Half Life	44.35 ± 0.29 m
Spin	1/2
Quadrupole Moment	0
Discovery Year	1954
Parity	+

¹²⁵Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹²⁶Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	125.909445821 ± 0.00001112 Da
Mass Number	126
G-Factor	0.776 ± 0.004
Half Life	1.64 ± 0.02 m
Spin	1
Quadrupole Moment	-0.64 ± 0.03
Discovery Year	1954
Parity	+

¹²⁶Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹²⁷Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	126.907417527 ± 0.000005987 Da
Mass Number	127
G-Factor	2.914 ± 0.014
Half Life	6.25 ± 0.1 h
Spin	1/2
Quadrupole Moment	0
Discovery Year	1950
Parity	+

¹²⁷Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹²⁸Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	127.907748452 ± 0.000005771 Da
Mass Number	128
G-Factor	0.972 ± 0.005
Half Life	3.64 ± 0.014 m
Spin	1
Quadrupole Moment	-0.54 ± 0.03
Discovery Year	1951
Parity	+

¹²⁸Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹²⁹Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	128.90606591 ± 0.000004888 Da
Mass Number	129
G-Factor	2.978 ± 0.016
Half Life	32.06 ± 0.06 h
Spin	1/2
Quadrupole Moment	0
Discovery Year	1950
Parity	+

¹²⁹Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹³⁰Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	129.906709281 ± 0.000008971 Da
Mass Number	130
G-Factor	1.458 ± 0.007
Half Life	29.21 ± 0.04 m
Spin	1
Quadrupole Moment	-0.056 ± 0.006
Discovery Year	1952
Parity	+

¹³⁰Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	98.4%
β⁻ (β⁻ decay)	1.6%

¹³¹Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	130.905468457 ± 0.00000019 Da
Mass Number	131
G-Factor	1.4144 ± 0.0012
Half Life	9.689 ± 0.016 d
Spin	5/2
Quadrupole Moment	0.59 ± 0.02
Discovery Year	1947
Parity	+

¹³¹Cs Decay Modes

Decay Mode	Intensity
ϵ (electron capture)	100%

¹³²Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	131.90643774 ± 0.000001112 Da
Mass Number	132
G-Factor	1.1095 ± 0.0035
Half Life	6.48 ± 0.006 d
Spin	2
Quadrupole Moment	0.48 ± 0.02
Discovery Year	1953
Parity	+

¹³²Cs Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	98.13%
β⁻ (β⁻ decay)	1.87%

¹³³Cs

Abundance	100
Relative Atomic Mass	132.905451958 ± 0.000000008 Da
Mass Number	133
G-Factor	0.73651428571429 ± 0.0004
Half Life
Spin	7/2
Quadrupole Moment	-0.00343 ± 0.0001
Discovery Year	1921
Parity	+

¹³⁴Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	133.906718501 ± 0.000000017 Da
Mass Number	134
G-Factor	0.747325 ± 0.00035
Half Life	2.065 ± 0.0004 y
Spin	4
Quadrupole Moment	0.37 ± 0.02
Discovery Year	1940
Parity	+

¹³⁴Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
ϵ (electron capture)	0.0003%

¹³⁵Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	134.905976907 ± 0.00000039 Da
Mass Number	135
G-Factor	0.77951428571429 ± 0.00037142857142857
Half Life	1.33 ± 0.19 My
Spin	7/2
Quadrupole Moment	0.048 ± 0.003
Discovery Year	1949
Parity	+

¹³⁵Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹³⁶Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	135.907311431 ± 0.00000201 Da
Mass Number	136
G-Factor	0.741 ± 0.003
Half Life	13.01 ± 0.05 d
Spin	5
Quadrupole Moment	0.213 ± 0.015
Discovery Year	1951
Parity	+

¹³⁶Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹³⁷Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	136.907089296 ± 0.000000324 Da
Mass Number	137
G-Factor	0.81068571428571 ± 0.0004
Half Life	30.04 ± 0.04 y
Spin	7/2
Quadrupole Moment	0.048 ± 0.002
Discovery Year	1951
Parity	+

¹³⁷Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹³⁸Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	137.911017119 ± 0.000009831 Da
Mass Number	138
G-Factor	0.233 ± 0.0013333333333333
Half Life	33.5 ± 0.2 m
Spin	3
Quadrupole Moment	0.112 ± 0.017
Discovery Year	1943
Parity	-

¹³⁸Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹³⁹Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	138.913363822 ± 0.000003364 Da
Mass Number	139
G-Factor	0.768 ± 0.0011428571428571
Half Life	9.27 ± 0.05 m
Spin	7/2
Quadrupole Moment	-0.063 ± 0.014
Discovery Year	1939
Parity	+

¹³⁹Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹⁴⁰Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	139.917283707 ± 0.000008801 Da
Mass Number	140
G-Factor	0.134 ± 0.001
Half Life	63.7 ± 0.3 s
Spin	1
Quadrupole Moment	-0.094 ± 0.015
Discovery Year	1950
Parity	-

¹⁴⁰Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹⁴¹Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	140.920045279 ± 0.000009871 Da
Mass Number	141
G-Factor	0.69457142857143 ± 0.0028571428571429
Half Life	24.84 ± 0.16 s
Spin	7/2
Quadrupole Moment	-0.42 ± 0.07
Discovery Year	1962
Parity	+

¹⁴¹Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	0.0342%

¹⁴²Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	141.924299514 ± 0.000007586 Da
Mass Number	142
G-Factor	0
Half Life	1.687 ± 0.01 s
Spin	0
Quadrupole Moment	0
Discovery Year	1962
Parity	-

¹⁴²Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	0.089%

¹⁴³Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	142.927347346 ± 0.00000813 Da
Mass Number	143
G-Factor	0.57933333333333 ± 0.0026666666666667
Half Life	1.802 ± 0.008 s
Spin	3/2
Quadrupole Moment	0.44 ± 0.03
Discovery Year	1962
Parity	+

¹⁴³Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	1.62%

¹⁴⁴Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	143.932075402 ± 0.000021612 Da
Mass Number	144
G-Factor	-0.545 ± 0.003
Half Life	994 ± 6 ms
Spin	1
Quadrupole Moment	0.29 ± 0.02
Discovery Year	1967
Parity	-

¹⁴⁴Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	2.98%

¹⁴⁵Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	144.935528927 ± 0.000009733 Da
Mass Number	145
G-Factor	0.522 ± 0.0026666666666667
Half Life	582 ± 4 ms
Spin	3/2
Quadrupole Moment	0.58 ± 0.06
Discovery Year	1971
Parity	+

¹⁴⁵Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	12.8%

¹⁴⁶Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	145.940621867 ± 0.000003106 Da
Mass Number	146
G-Factor	-0.514 ± 0.002
Half Life	321.6 ± 0.9 ms
Spin	1
Quadrupole Moment	0.21 ± 0.03
Discovery Year	1971
Parity	-

¹⁴⁶Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	14.2%
2n (2-neutron emission)	%

¹⁴⁷Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	146.944261512 ± 0.000009 Da
Mass Number	147
G-Factor
Half Life	230.5 ± 0.9 ms
Spin	3/2
Quadrupole Moment
Discovery Year	1978
Parity	+

¹⁴⁷Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	28.5%

¹⁴⁸Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	147.949639026 ± 0.000014 Da
Mass Number	148
G-Factor
Half Life	151.8 ± 1 ms
Spin	2
Quadrupole Moment
Discovery Year	1978
Parity	-

¹⁴⁸Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	28.7%
2n (2-neutron emission)	%

¹⁴⁹Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	148.953516 ± 0.000429 Da
Mass Number	149
G-Factor
Half Life	112.3 ± 2.5 ms
Spin	3/2
Quadrupole Moment
Discovery Year	1979
Parity	+

¹⁴⁹Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	25%
2n (2-neutron emission)	%

¹⁵⁰Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	149.959023 ± 0.000429 Da
Mass Number	150
G-Factor
Half Life	81 ± 2.6 ms
Spin	2
Quadrupole Moment
Discovery Year	1979
Parity	-

¹⁵⁰Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	44%
2n (2-neutron emission)	%

¹⁵¹Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	150.963199 ± 0.000537 Da
Mass Number	151
G-Factor
Half Life	59 ± 19 ms
Spin	3/2
Quadrupole Moment
Discovery Year	1979
Parity	+

¹⁵¹Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%
2n (2-neutron emission)	%

¹⁵²Cs

Abundance	Radioactive ☢️
Relative Atomic Mass	151.968728 ± 0.000537 Da
Mass Number	152
G-Factor
Half Life
Spin
Quadrupole Moment
Discovery Year	1987
Parity

¹⁵²Cs Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%

History

Robert Bunsen and Gustav Kirchhoff were the first to suggest finding cesium in 1860 by spectrum analysis. They discovered cesium by its two blue emission lines in a sample of Dürkheim mineral water. The pure metal was eventually isolated by the German chemist Carl Setterberg while working on his doctorate with Kekulé and Bunsen. From the Latin word caesius, sky blue

Discoverers	Gustov Kirchoff, Robert Bunsen
Discovery Location	Germany
Discovery Year	1860
Etymology (Name Origin)	Latin: coesius (sky blue); for the blue lines of its spectrum.
Pronunciation	SEE-zi-em (English)

Cesium compounds are considered to be mildly toxic

Cesium was the first element discovered using a spectroscope

Uses

The radioactive isotope cesium-137 has a half-life of about 30 years and is used in medical applications, industrial gauges, and hydrology. Cesium is also used in photoelectric cells and as a catalyst in the hydrogenation of organic compounds. Cesium vapor thermionic generators are low-power devices that convert heat energy to electrical energy. Used as a 'getter' to remove air traces in vacuum and cathode-ray tubes. Also used in producing photoelectric devices and atomic clocks. Since it ionizes readily, it is used as an ion rocket motor propellant.

Sources

Found in pollucite [(Cs4Al4Si9O26).H2O] and as trace in lepidolite.

Abundance
Abundance in Earth's crust	3 mg/kg
Abundance in Oceans	0.0003 mg/L
Abundance in Human Body	0.000002 %
Abundance in Meteor	0.000014 %
Abundance in Sun	0.0000008 %
Abundance in Universe	0.00000008 %

Nuclear Screening Constants

1	s	1.0957
2	p	4.1804
2	s	14.4884
3	d	14.0194
3	p	18.4222
3	s	18.6226
4	d	32.1616
4	p	29.1424
4	s	27.9576
5	p	41.349
5	s	39.5555
6	s	48.637

Cesium on ChemicalAid

AGROVOC ID	c_1182
Art & Architecture Thesaurus ID	300380498
Australian Educational Vocabulary ID	scot/3063
BNCF Thesaurus ID	22890
Bibliothèque nationale de France ID	121655651
Brockhaus Enzyklopädie online ID	cäsium
CAB ID	18776
CAS Registry Number	7440-46-2
Cannabis Database ID	006361
ChEBI ID	30514
ChemSpider ID	4510778
Common Procurement Vocabulary	14771000
DSSTOX compound identifier	DTXCID40820345
DSSTox substance ID	DTXSID5036767
Den Store Danske ID	cæsium
DrugBank ID	15392
ECHA Substance Infocard ID	100.028.323
Encyclopædia Britannica Online ID	science/cesium
Encyclopædia Universalis ID	cesium
Freebase ID	/m/025tnb6
French Vikidia ID	Césium
GND ID	4147131-3
Gran Enciclopèdia Catalana ID	0090224
Great Russian Encyclopedia Online ID	4674014
HSDB ID	7040
Hrvatska enciklopedija ID	11373
Human Metabolome Database ID	HMDB0013669
InChI	InChI=1S/Cs
InChIKey	TVFDJXOCXUVLDH-UHFFFAOYSA-N
KBpedia ID	Cesium
Krugosvet article	himiya/ceziy
Library of Congress authority ID	sh85022200
MeSH descriptor ID	D002586
NDL Authority ID	00570840
NE.se ID	cesium
NKCR AUT ID	ph124977
National Library of Israel J9U ID	987007284955105171
OmegaWiki Defined Meaning	470
OpenAlex ID	C519659679
PSH ID	5748
PubChem CID	5354618
Quora topic ID	Cesium
RxNorm ID	1310121
Store norske leksikon ID	cesium
Treccani ID	cesio
UNII	1KSV9V4Y4I
USGS Thesaurus ID	1424
WordNet 3.1 Synset ID	14658410-n
YSO ID	16504
ZVG number	7550

Cesium (Cs)

Properties

Isotopes of Cesium

111Cs

111Cs Decay Modes

112Cs

112Cs Decay Modes

113Cs

113Cs Decay Modes

114Cs

114Cs Decay Modes

115Cs

115Cs Decay Modes

116Cs

116Cs Decay Modes

117Cs

117Cs Decay Modes

118Cs

118Cs Decay Modes

119Cs

119Cs Decay Modes

120Cs

120Cs Decay Modes

121Cs

121Cs Decay Modes

122Cs

122Cs Decay Modes

123Cs

123Cs Decay Modes

124Cs

124Cs Decay Modes

125Cs

125Cs Decay Modes

126Cs

126Cs Decay Modes

127Cs

127Cs Decay Modes

128Cs

128Cs Decay Modes

129Cs

129Cs Decay Modes

130Cs

130Cs Decay Modes

131Cs

131Cs Decay Modes

132Cs

132Cs Decay Modes

133Cs

134Cs

134Cs Decay Modes

135Cs

135Cs Decay Modes

136Cs

136Cs Decay Modes

137Cs

137Cs Decay Modes

138Cs

138Cs Decay Modes

139Cs

139Cs Decay Modes

140Cs

140Cs Decay Modes

141Cs

141Cs Decay Modes

142Cs

142Cs Decay Modes

143Cs

143Cs Decay Modes

144Cs

144Cs Decay Modes

145Cs

145Cs Decay Modes

146Cs

146Cs Decay Modes

147Cs

147Cs Decay Modes

148Cs

148Cs Decay Modes

149Cs

149Cs Decay Modes