Template:Infobox caesium

Caesium
55Cs
Rb ↑ Cs ↓ Fr Periodic table xenon ← caesium → barium
Appearance
silvery gold
General properties
Name, symbol, number	caesium, Cs, 55
Pronunciation	/ˈsiːziəm/ SEE-zee-əm
Element category	alkali metal
Group, period, block	1 (alkali metals), 6, s
Standard atomic weight	132.9054519(2)
Electron configuration	[Xe] 6s1 2, 8, 18, 18, 8, 1
History
Discovery	Robert Bunsen and Gustav Kirchhoff (1860)
First isolation	Carl Setterberg (1882)
Physical properties
Phase	solid
Density (near r.t.)	1.93 g·cm−3
Liquid density at m.p.	1.843 g·cm−3
Melting point	301.59 K, 28.44 °C, 83.19 °F
Boiling point	944 K, 671 °C, 1240 °F
Critical point	1938 K, 9.4 MPa
Heat of fusion	2.09 kJ·mol−1
Heat of vaporization	63.9 kJ·mol−1
Molar heat capacity	32.210 J·mol−1·K−1
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 418 469 534 623 750 940
Atomic properties
Oxidation states	1 (strongly basic oxide)
Electronegativity	0.79 (Pauling scale)
Ionization energies	1st: 375.7 kJ·mol−1
	2nd: 2234.3 kJ·mol−1
	3rd: 3400 kJ·mol−1
Atomic radius	265 pm
Covalent radius	244±11 pm
Van der Waals radius	343 pm
Miscellanea
Crystal structure	body-centered cubic
Magnetic ordering	paramagnetic
Electrical resistivity	(20 °C) 205 nΩ·m
Thermal conductivity	35.9 W·m−1·K−1
Thermal expansion	(25 °C) 97 µm·m−1·K−1
Young's modulus	1.7 GPa
Bulk modulus	1.6 GPa
Mohs hardness	0.2
Brinell hardness	0.14 MPa
CAS registry number	7440-46-2
Most stable isotopes
Main article: Isotopes of caesium
iso NA half-life DM DE (MeV) DP 133Cs 100% 133Cs is stable with 78 neutrons 134Cs syn 2.0648 y ε 1.229 134Xe β− 2.059 134Ba 135Cs trace 2.3×106 y β− 0.269 135Ba 137Cs trace 30.17 y β− 1.174 137Ba

References

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