Caesium

Caesium, ₅₅Cs
Caesium
Pronunciation	/ˈsiːziəm/ (SEE-zee-əm)
Appearance	sillery gowd
Standard atomic weight Ar, std(Cs)	132.90545196(6)
Caesium in the periodic cairt
	xenon ← caesium → barium
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)
Atomic properties
Oxidation states	−1, +1 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
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
β−	134Ba
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Caesium or cesium^{[note 1]} is a chemical element wi seembol Cs an atomic nummer 55. It is a saft, sillery-gowd alkali metal wi a meltin pynt o 28 °C (82 °F), which maks it ane o anly five elemental metals that are liquid at or near ruim temperatur.^{[note 2]} Caesium is an alkali metal an haes pheesical an chemical properties seemilar tae those o rubidium an potassium. The metal is extremely reactive an pyrophoric, reactin wi watter even at −116 °C (−177 °F). It is the least electronegative element havin a stable isotope, caesium-133. Caesium is mined maistly frae pollucite, while the radioisotopes, especially caesium-137, a fission product, are extractit frae waste produced bi nuclear reactors.

Twa German chemists, Robert Bunsen an Gustav Kirchhoff, discovered caesium in 1860 bi the newly developed method o flame spectroscopy. The first smaa-scale applications for caesium wur as a "getter" in vacuum tubes an in photoelectric cells. In 1967, a specific frequency frae the emission spectrum o caesium-133 wis chosen tae be uised in the definition o the seicont bi the Internaitional Seestem o Units. Syne then, caesium haes been widely uised in atomic clocks.

Syne the 1990s, the lairgest application o the element haes been as caesium formate for drilling fluids. It haes a range o applications in the production o electricity, in electronics, an in chemistry. The radioactive isotope caesium-137 haes a hauf-life o aboot 30 year an is uised in medical applications, industrial gauges, an hydrology. Altho the element is anly mildly toxic, it is a hazardous material as a metal an its radioisotopes present a heich heal risk if released intae the environment.

Notes

↑ Caesium is the spellin recommendit bi the Internaitional Union o Pure an Applee'd Chemistry (IUPAC).^[5] The American Chemical Society (ACS) haes uised the spellin cesium syne 1921,^[6]^[7] follaein Webster's New International Dictionary. The element wis named efter the Latin word cæsius, meanin "bluish gray".^[8] Hence, an alternative orthography is cæsium. Mair spellin explanation at ae/oe vs e.
↑ Alang wi rubidium (39 °C [102 °F]), francium (estimatit at 27 °C [81 °F]), mercur (−39 °C [−38 °F]), an gallium (30 °C [86 °F]); bromine is an aa liquid at ruim temperatur (meltin at −7.2 °C, 19 °F) but it is a halogen, nae a metal.

References

↑ Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
↑ Dye, J. L. (1979). "Compounds of Alkali Metal Anions". Angewandte Chemie International Edition. 18 (8): 587–598. doi:10.1002/anie.197905871.
↑ "Magnetic susceptibility of the elements and inorganic compounds". Handbook of Chemistry and Physics (PDF) (87th ed.). CRC press. ISBN 0-8493-0487-3. Retrieved 26 September 2010.
↑ "NIST Radionuclide Half-Life Measurements". NIST. Retrieved 13 Mairch 2011.
↑ Internaitional Union o Pure an Applee'd Chemistry (2005). Nomenclature o Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8. pp. 248–49. Electronic version..
↑ Coghill, Anne M.; Garson, Lorrin R., eds. (2006). The ACS Style Guide: Effective Communication of Scientific Information (3rd ed.). Washington, D.C.: American Chemical Society. p. 127. ISBN 0-8412-3999-1.
↑ Coplen, T. B.; Peiser, H. S. (1998). "History of the recommended atomic-weight values from 1882 to 1997: a comparison of differences from current values to the estimated uncertainties of earlier values" (PDF). Pure Appl. Chem. 70 (1): 237–257. doi:10.1351/pac199870010237.
↑ OED entry for "caesium". Second edition, 1989; online version June 2012; accessed 07 September 2012. Earlier version first published in New English Dictionary, 1888.

Freemit airtins

Caesium or Cesium at The Periodic Table o Videos (Varsity o Nottingham)
Humor steid dedicatit tae caesium

[9] Caesium is the spellin recommendit bi the Internaitional Union o Pure an Applee'd Chemistry (IUPAC).^[5] The American Chemical Society (ACS) haes uised the spellin cesium syne 1921,^[6]^[7] follaein Webster's New International Dictionary. The element wis named efter the Latin word cæsius, meanin "bluish gray".^[8] Hence, an alternative orthography is cæsium. Mair spellin explanation at ae/oe vs e.

[10] Alang wi rubidium (39 °C [102 °F]), francium (estimatit at 27 °C [81 °F]), mercur (−39 °C [−38 °F]), an gallium (30 °C [86 °F]); bromine is an aa liquid at ruim temperatur (meltin at −7.2 °C, 19 °F) but it is a halogen, nae a metal.

[CIAAW2013-1] Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.

[caeside-2] Dye, J. L. (1979). "Compounds of Alkali Metal Anions". Angewandte Chemie International Edition. 18 (8): 587–598. doi:10.1002/anie.197905871.

[magnet-3] "Magnetic susceptibility of the elements and inorganic compounds". Handbook of Chemistry and Physics (PDF) (87th ed.). CRC press. ISBN 0-8493-0487-3. Retrieved 26 September 2010.

[isotope-4] "NIST Radionuclide Half-Life Measurements". NIST. Retrieved 13 Mairch 2011.

[5] Internaitional Union o Pure an Applee'd Chemistry (2005). Nomenclature o Inorganic Chemistry (IUPAC Recommendations 2005). Cambridge (UK): RSC–IUPAC. ISBN 0-85404-438-8. pp. 248–49. Electronic version..

[6] Coghill, Anne M.; Garson, Lorrin R., eds. (2006). The ACS Style Guide: Effective Communication of Scientific Information (3rd ed.). Washington, D.C.: American Chemical Society. p. 127. ISBN 0-8412-3999-1.

[7] Coplen, T. B.; Peiser, H. S. (1998). "History of the recommended atomic-weight values from 1882 to 1997: a comparison of differences from current values to the estimated uncertainties of earlier values" (PDF). Pure Appl. Chem. 70 (1): 237–257. doi:10.1351/pac199870010237.

[8] OED entry for "caesium". Second edition, 1989; online version June 2012; accessed 07 September 2012. Earlier version first published in New English Dictionary, 1888.

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