![Template:Infobox element/symbol-to-top-image/alt](//upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Cesium.jpg/220px-Cesium.jpg) |
Caesium |
---|
Pronunciation | (SEE-zee-əm) |
---|
Appearance | sillery gowd |
---|
Standard atomic weight Ar, std(Cs) | 7002132905451960000♠132.90545196(6)[1] |
---|
Caesium in the periodic cairt |
---|
|
Atomic nummer (Z) | 55 |
---|
Group | group 1 (alkali metals) |
---|
Period | period 6 |
---|
Block | s-block |
---|
Element category | Alkali metal |
---|
Electron confeeguration | [Xe] 6s1 |
---|
Electrons per shell | 2, 8, 18, 18, 8, 1 |
---|
Pheesical properties |
---|
Phase at STP | solit |
---|
Meltin pynt | 301.59 K (28.44 °C, 83.19 °F) |
---|
Bylin pynt | 944 K (671 °C, 1240 °F) |
---|
Density (near r.t.) | 1.93 g/cm3 |
---|
when liquid (at m.p.) | 1.843 g/cm3 |
---|
Creetical pynt | 1938 K, 9.4 MPa |
---|
Heat o fusion | 2.09 kJ/mol |
---|
Heat o vapourisation | 63.9 kJ/mol |
---|
Molar heat capacity | 32.210 J/(mol·K) |
---|
Vapour pressur
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, +1[2] strangly basic |
---|
Electronegativity | Pauling scale: 0.79 |
---|
Atomic radius | empirical: 265 pm |
---|
Covalent radius | 244±11 pm |
---|
Van der Waals radius | 343 pm |
---|
Colour lines in a spectral rangeSpectral lines o caesium |
Ither properties |
---|
Naitural occurrence | primordial |
---|
Creestal structur | body-centred cubic (bcc) |
---|
Thermal expansion | 97 µm/(m·K) (at 25 °C) |
---|
Thermal conductivity | 35.9 W/(m·K) |
---|
Electrical resistivity | 205 n Ω·m (at 20 °C) |
---|
Magnetic orderin | paramagnetic[3] |
---|
Young's modulus | 1.7 GPa |
---|
Bulk modulus | 1.6 GPa |
---|
Mohs haurdness | 0.2 |
---|
Brinell haurdness | 0.14 MPa |
---|
CAS Nummer | 7440-46-2 |
---|
History |
---|
Diskivery | Robert Bunsen an Gustav Kirchhoff (1860) |
---|
First isolation | Carl Setterberg (1882) |
---|
Main isotopes o caesium |
---|
Isotope |
Abundance |
Hauf-life (t1/2) |
Decay mode |
Product |
133Cs |
100% |
stable |
134Cs |
syn |
2.0648 y |
ε |
134Xe |
β− |
134Ba |
135Cs |
trace |
2.3×106 y |
β− |
135Ba |
137Cs |
trace |
30.17 y[4] |
β− |
137Ba |
|
| references |