About Cesium
With one electron in its sixth and outermost shell, cesium (or caesium) is the most electropositive of all stable elements on the periodic table: the metal is extremely pyrophoric, spontaneously igniting when it comes into contact with air and exploding violently in water or ice at any temperature above -116 °C. Though cesium is only mildly toxic, it is classified as hazardous because of its high reactivity and is usually packaged in glass ampoules in a vacuum or under an inert gas such as argon. The heaviest of the stable alkali metals, cesium is silvery-gold in appearance, ductile, and the softest element on the periodic table at 0.2 on the Mohs scale. Cesium melts at 28 °C, making it one of three elements (the others being gallium and mercury) that are liquid at or near room temperature; mercury is the only element with a lower melting point. Only one of cesium’s known isotopes is stable (133Cs), but its total of 39 makes it tied with xenon as the two elements with the most amount of known isotopes. Cesium was also the first element to be discovered via spectroscopy by German scientists Robert Bunsen and Gustav Kirchhoff, who had invented the technology the previous year. Bunsen and Kirchhoff gave the new element a name based on the Latin word caesius (sky or heavenly blue) for the two brilliant blue lines emitted in its spectrum.
Cesium is the 45th most abundant element on earth, found in the minerals pollucite, avogadrite, pezzottaite, londonite, rhodizite, beryl, and some potassium ores; the primary commercial source of metallic cesium is from the mining of pollucite, while cesium radioisotopes are produced from nuclear reactor waste. Oxygen-free metallic cesium can also be produced via the thermal decomposition of cesium azide (CsN3). Laboratories use cesium compounds for various organic chemistry functions such as the hydrogenation of organic compounds or, in the case of cesium fluoride, as a source of the fluorine anion. X-ray radiotherapy in cancer treatment often employs radioactive isotope cesium-137. In commercial and industrial applications, cesium salts can serve as catalyst promoters, glass strengtheners, components of photoelectric cells, crystals in scintillation counters, and “getters” in vacuum tubes; cesium formate brines are commonly utilized in oil drilling to lubricate drill bits and maintain pressure. Thermionic energy converters use a vapor of cesium ions to determine the work function of the electrodes. Early ion propulsion engines for space exploration used cesium as a propellant until xenon became the standard. The most accurate commercially available atomic clocks keep time using the oscillation of the cesium-133 atom’s 9193 MHz hyperfine transition frequency. Known as the “cesium standard,” this frequency is the primary time standard for the definition of the second and is critical to the data transmission infrastructures of cell phone networks, GPS, and the internet.
Products
Cesium is used as an oxygen "getter" in vacuum and electronic tubes and as a component of photoelectric cells. Atomic clocks use the microwave spectral line emitted by Cesium-133 for reference. Radioactive Cesium-137 is an artificial isotope that is used for cancer radiotherapy. 
Laboratories use various cesium compounds for their ability to hydrogenate organic compounds. Cesium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Nanoparticles and nanopowders provide ultra-high surface area which nanotechnology research and recent experiments demonstrate function to create new and unique properties and benefits. Oxides are available in forms including powders and dense pellets for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Cesium is available in soluble forms including chlorides, nitrates and acetates. These compounds are also manufactured as solutions at specified stoichiometries.
Cesium Properties
Cesium (or Caesium ) is a Block S, Group 1, Period 6 element. The number of electrons in each of Cesium's shells is 2, 8, 18, 18, 8, 1 and its electronic configuration is [Xe] 6s1. The cesium atom has a radius of 265.5.pm and its Van der Waals radius is 200.pm. In its elemental form, CAS 7440-46-2, cesium has a silvery gold appearance. Cesium is a member of the alkali group of metals. It is one of three metals that occur as a liquid at room 
high purity properties, research, applications and other useful facts are discussed below. Scientific facts such as the atomic structure, ionization energy, abundance on earth, conductivity and thermal properties are also included.
Health, Safety & Transportation Information for Cesium
| Safety Data | |
|---|---|
| Signal Word | Danger |
| Hazard Statements | H260-H314 |
| Hazard Codes | F,C |
| Risk Codes | 11-14/15-34 |
| Safety Precautions | 8-16-26-36/37/39-43-45 |
| RTECS Number | FK9225000 |
| Transport Information | UN 1415 4.3/PG 1 |
| WGK Germany | 3 |
| Globally Harmonized System of Classification and Labelling (GHS) |
 |
SECTION 1. IDENTIFICATION
Product Name: Cesium Metal
Product Number: All applicable American Elements product codes, e.g. CS-M-02, CS-M-03, CS-M-04, CS-M-05
CAS #: 7440-46-2
Relevant identified uses of the substance: Scientific research and development
Supplier details:
American Elements
1093 Broxton Ave. Suite 2000
Los Angeles, CA 90024
Tel: +1 310-208-0551
Fax: +1 310-208-0351
Emergency telephone number:
Domestic, North America +1 800-424-9300
International +1 703-527-3887
SECTION 2. HAZARDS IDENTIFICATION
Classification of the substance or mixture
Classification according to Regulation (EC) No 1272/2008
GHS02 Flame
Water-react. 1 H260 In contact with water releases flammable gases which may ignite spontaneously.
GHS05 Corrosion
Skin Corr. 1B H314 Causes severe skin burns and eye damage.
Eye Dam. 1 H318 Causes serious eye damage.
Hazards not otherwise classified
No information known.
Label elements
Labelling according to Regulation (EC) No 1272/2008
The substance is classified and labeled according to the CLP regulation.
Hazard pictograms
GHS02 GHS05
Signal word
Danger
Hazard statements
H260 In contact with water releases flammable gases which may ignite spontaneously.
H314 Causes severe skin burns and eye damage.
Precautionary statements
P231+P232 Handle under inert gas. Protect from moisture.
P260 Do not breathe dust/fume/gas/mist/vapours/spray.
P303+P361+P353 IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water/shower.
P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
P405 Store locked up.
P501 Dispose of contents/container in accordance with local/regional/
national/international regulations.
WHMIS classification
B6 - Reactive flammable material
D2B - Toxic material causing other toxic effects
E - Corrosive material
Classification system
HMIS ratings (scale 0-4)
(Hazardous Materials Identification System)
HEALTH
FIRE
REACTIVITY
3
4
3
Health (acute effects) = 3
Flammability = 4
Physical Hazard = 3
Other hazards
Results of PBT and vPvB assessment
PBT:
Not applicable.
vPvB:
Not applicable
SECTION 3. COMPOSITION/INFORMATION ON INGREDIENTS
Chemical characterization: Substances
CAS# Description:
7440-46-2 Cesium
Identification number(s):
EC number:
231-155-4
SECTION 4. FIRST AID MEASURES
Description of first aid measures
General information
Immediately remove any clothing soiled by the product.
After inhalation
Supply fresh air. If required, provide artificial respiration. Keep patient warm.
Seek immediate medical advice.
After skin contact
Immediately wash with water and soap and rinse thoroughly.
Seek immediate medical advice.
After eye contact
Rinse opened eye for several minutes under running water. Then consult a doctor.
After swallowing
Seek medical treatment.
Information for doctor
Most important symptoms and effects, both acute and delayed
Causes severe skin burns.
Causes serious eye damage.
Indication of any immediate medical attention and special treatment needed
No further relevant information available.
SECTION 5. FIREFIGHTING MEASURES
Extinguishing media
Suitable extinguishing agents
Special powder for metal fires. Do not use water.
For safety reasons unsuitable extinguishing agents
Water
Special hazards arising from the substance or mixture
Reacts violently with water
If this product is involved in a fire, the following can be released:
Metal oxide fume
Advice for firefighters
Protective equipment:
Wear self-contained respirator.
Wear fully protective impervious suit.
SECTION 6. ACCIDENTAL RELEASE MEASURES
Personal precautions, protective equipment and emergency procedures
Wear protective equipment. Keep unprotected persons away.
Ensure adequate ventilation
Keep away from ignition sources
Environmental precautions:
Do not allow material to be released to the environment without proper governmental permits.
Methods and material for containment and cleaning up:
Keep away from ignition sources.
Use neutralizing agent.
Dispose of contaminated material as waste according to section 13.
Ensure adequate ventilation.
Do not flush with water or aqueous cleansing agents
Prevention of secondary hazards:
Keep away from ignition sources.
Reference to other sections
See Section 7 for information on safe handling
See Section 8 for information on personal protection equipment.
See Section 13 for disposal information.
SECTION 7. HANDLING AND STORAGE
Handling
Precautions for safe handling
Handle under dry protective gas.
Keep container tightly sealed.
Store in cool, dry place in tightly closed containers.
Ensure good ventilation at the workplace.
Reacts violently with water
Information about protection against explosions and fires:
Protect from humidity and water.
Conditions for safe storage, including any incompatibilities
Storage
Requirements to be met by storerooms and receptacles:
No special requirements.
Information about storage in one common storage facility:
Store away from water/moisture.
Store away from air.
Further information about storage conditions:
Store under dry inert gas.
Protect from humidity and water.
Keep container tightly sealed.
Store in cool, dry conditions in well sealed containers.
Specific end use(s)
No further relevant information available.
SECTION 8. EXPOSURE CONTROLS/PERSONAL PROTECTION
Additional information about design of technical systems:
Properly operating chemical fume hood designed for hazardous chemicals and having an average face velocity of at least 100 feet per minute.
Control parameters
Components with limit values that require monitoring at the workplace:
The product does not contain any relevant quantities of materials with critical values that have to be monitored at the workplace.
Additional information:
No data
Exposure controls
Personal protective equipment
General protective and hygienic measures
The usual precautionary measures for handling chemicals should be followed.
Keep away from foodstuffs, beverages and feed.
Remove all soiled and contaminated clothing immediately.
Wash hands before breaks and at the end of work.
Avoid contact with the eyes and skin.
Maintain an ergonomically appropriate working environment.
Breathing equipment:
Use suitable respirator when high concentrations are present.
Protection of hands:
Impervious gloves
Check protective gloves prior to each use for their proper condition.
The selection of suitable gloves not only depends on the material, but also on quality. Quality will vary from manufacturer to manufacturer.
Penetration time of glove material (in minutes)
Not determined
Eye protection:
Tightly sealed goggles
Full face protection
Body protection:
Protective work clothing
SECTION 9. PHYSICAL AND CHEMICAL PROPERTIES
Information on basic physical and chemical properties
General Information
Appearance:
Form: Solid
Color: Silver-colored
Odor: Odorless
Odor threshold: Not determined.
pH-value: Not applicable.
Change in condition
Melting point/Melting range: 28.4 °C (83 °F)
Boiling point/Boiling range: 671 °C (1240 °F)
Sublimation temperature / start: Not determined
Flammability (solid, gaseous)
Contact with water liberates extremely flammable gases.
Ignition temperature: Not determined
Decomposition temperature: Not determined
Auto igniting: Not determined.
Danger of explosion: Not determined.
Explosion limits:
Lower: Not determined
Upper: Not determined
Vapor pressure at 20 °C (68 °F): 0.0000011 hPa
Density at 20 °C (68 °F): 1.873 g/cm³ (15.63 lbs/gal)
Relative density
Not determined.
Vapor density
Not applicable.
Evaporation rate
Not applicable.
Solubility in / Miscibility with Water: Reacts violently
Contact with water releases flammable gases
Partition coefficient (n-octanol/water): Not determined.
Viscosity:
dynamic: Not applicable.
kinematic: Not applicable.
Other information
No further relevant information available.
SECTION 10. STABILITY AND REACTIVITY
Reactivity
Reacts violently with water.
In contact with water releases flammable gases which may ignite spontaneously.
Chemical stability
Stable under recommended storage conditions.
Thermal decomposition / conditions to be avoided:
Decomposition will not occur if used and stored according to specifications.
Possibility of hazardous reactions
Contact with water releases flammable gases
Reacts violently with water
Conditions to avoid
No further relevant information available.
Incompatible materials:
Air
Water/moisture
Hazardous decomposition products:
Metal oxide fume
SECTION 11. TOXICOLOGICAL INFORMATION
Information on toxicological effects
Acute toxicity:
Swallowing will lead to a strong corrosive effect on mouth and throat and to the danger of perforation of esophagus and stomach.
The Registry of Toxic Effects of Chemical Substances (RTECS) contains acute toxicity data for this substance.
LD/LC50 values that are relevant for classification:
No data
Skin irritation or corrosion:
Causes severe skin burns.
Eye irritation or corrosion:
Causes serious eye damage.
Sensitization:
No sensitizing effects known.
Germ cell mutagenicity:
No effects known.
Carcinogenicity:
No classification data on carcinogenic properties of this material is available from the EPA, IARC, NTP, OSHA or ACGIH.
Reproductive toxicity:
No effects known.
Specific target organ system toxicity - repeated exposure:
No effects known.
Specific target organ system toxicity - single exposure:
No effects known.
Aspiration hazard:
No effects known.
Subacute to chronic toxicity:
No effects known.
Additional toxicological information:
To the best of our knowledge the acute and chronic toxicity of this substance is not fully known.
Carcinogenic categories
OSHA-Ca (Occupational Safety & Health Administration)
Substance is not listed.
SECTION 12. ECOLOGICAL INFORMATION
Toxicity
Aquatic toxicity:
No further relevant information available.
Persistence and degradability
No further relevant information available.
Bioaccumulative potential
No further relevant information available.
Mobility in soil
No further relevant information available.
Additional ecological information:
General notes:
Do not allow material to be released to the environment without proper governmental permits.
Do not allow undiluted product or large quantities to reach ground water, water course or sewage system.
Avoid transfer into the environment.
Results of PBT and vPvB assessment
PBT:
Not applicable.
vPvB:
Not applicable.
Other adverse effects
No further relevant information available.
SECTION 13. DISPOSAL CONSIDERATIONS
Waste treatment methods
Recommendation
Consult state, local or national regulations to ensure proper disposal.
Uncleaned packagings:
Recommendation:
Disposal must be made according to official regulations.
SECTION 14. TRANSPORT INFORMATION
UN-Number
DOT, IMDG, IATA
UN1407
UN proper shipping name
DOT
Cesium
IMDG, IATA
CAESIUM
Transport hazard class(es)
DOT
Class
4.3 Substances which, in contact with water, emit flammable gases.
Label
4.3
Class
4.3 (W2) Substances which, in contact with water, emit flammable gases
Label
4.3
IMDG, IATA
Class
4.3 Substances which, in contact with water, emit flammable gases.
Label
4.3
Packing group
DOT, IMDG, IATA
I
Environmental hazards:
Not applicable.
Special precautions for user
Warning: Substances which, in contact with water, emit flammable gases
EMS Number: F-G,S-N
Transport in bulk according to Annex II of MARPOL73/78 and the IBC Code
Not applicable.
Transport/Additional information: DOT
Marine Pollutant (DOT): No
UN "Model Regulation":
UN1407, Cesium, 4.3, I
SECTION 15. REGULATORY INFORMATION
Safety, health and environmental regulations/legislation specific for the substance or mixture
National regulations
All components of this product are listed in the U.S. Environmental Protection Agency Toxic Substances Control Act Chemical substance Inventory.
All components of this product are listed on the Canadian Non-Domestic Substances List (NDSL).
SARA Section 313 (specific toxic chemical listings)
Substance is not listed.
California Proposition 65
Prop 65 - Chemicals known to cause cancer
Substance is not listed.
Prop 65 - Developmental toxicity
Substance is not listed.
Prop 65 - Developmental toxicity, female
Substance is not listed.
Prop 65 - Developmental toxicity, male
Substance is not listed.
Information about limitation of use:
For use only by technically qualified individuals.
Other regulations, limitations and prohibitive regulations
Substance of Very High Concern (SVHC) according to the REACH Regulations (EC) No. 1907/2006.
Substance is not listed.
The conditions of restrictions according to Article 67 and Annex XVII of the Regulation (EC) No 1907/2006 (REACH) for the manufacturing, placing on the market and use must be observed.
Substance is not listed.
Annex XIV of the REACH Regulations (requiring Authorisation for use)
Substance is not listed.
Chemical safety assessment:
A Chemical Safety Assessment has not been carried out.
16. OTHER INFORMATION
Safety Data Sheet according to Regulation (EC) No. 1907/2006 (REACH). The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. American Elements shall not be held liable for any damage resulting from handling or from contact with the above product. See reverse side of invoice or packing slip for additional terms and conditions of sale. COPYRIGHT 1997-2016 AMERICAN ELEMENTS. LICENSED GRANTED TO MAKE UNLIMITED PAPER COPIES FOR INTERNAL USE ONLY.
Cesium Isotopes
Cesium (Caesium, Cs) has 40 known isotopes with atomic masses ranging from 112 to 151. 133Cs is the only stable isotope.
| Nuclide | Isotopic Mass | Half-Life | Mode of Decay | Nuclear Spin | Magnetic Moment | Binding Energy (MeV) | Natural Abundance (% by atom) |
|---|---|---|---|---|---|---|---|
| 112Cs | 111.95030(33)# | 500(100) µs | p to 111Xe; a to 108I | 1+# | N/A | 889.68 | - |
| 113Cs | 112.94449(11) | 16.7(7) µs | p to 112Xe; ß+ to 113Xe | 5/2+# | N/A | 907.08 | - |
| 114Cs | 113.94145(33)# | 0.57(2) s | ß+ to 114Xe; ß+ + p to 113I; ß+ + a to 110Te; a to 110I | (1+) | N/A | 915.16 | - |
| 115Cs | 114.93591(32)# | 1.4(8) s | ß+ to 115Xe; ß+ + p to 114I | 9/2+# | N/A | 932.55 | - |
| 116Cs | 115.93337(11)# | 0.70(4) s | ß+ to 116Xe; ß+ + p to 115I; ß+ + a to 112Te | (1+) | N/A | 940.63 | - |
| 117Cs | 116.92867(7) | 8.4(6) s | ß+ to 117Xe | (9/2+)# | N/A | 958.03 | - |
| 118Cs | 117.926559(14) | 14(2) s | ß+ to 118Xe; ß+ + p to 117I; ß+ + a to 114Te | 2 | N/A | 966.1 | - |
| 119Cs | 118.922377(15) | 43.0(2) s | ß+ to 119Xe; ß+ + a to 115Te | 9/2+ | N/A | 974.18 | - |
| 120Cs | 119.920677(11) | 61.2(18) s | ß+ to 120Xe; ß+ + a to 116Te; ß+ + p to 118I | 2(-#) | N/A | 982.26 | - |
| 121Cs | 120.917229(15) | 155(4) s | ß+ to 121Xe | 3/2(+) | N/A | 999.66 | - |
| 122Cs | 121.91611(3) | 21.18(19) s | ß+ to 122Xe; ß+ + a to 118Te | 1+ | N/A | 1007.74 | - |
| 123Cs | 122.912996(13) | 5.88(3) min | ß+ to 123Xe | 1/2+ | N/A | 1015.81 | - |
| 124Cs | 123.912258(9) | 30.9(4) s | ß+ to 124Xe | 1+ | N/A | 1023.89 | - |
| 125Cs | 124.909728(8) | 46.7(1) min | ß+ to 125Xe | 1/2(+) | N/A | 1041.29 | - |
| 126Cs | 125.909452(13) | 1.64(2) min | ß+ to 126Xe | 1+ | N/A | 1049.37 | - |
| 127Cs | 126.907418(6) | 6.25(10) h | ß+ to 127Xe | 1/2+ | N/A | 1057.45 | - |
| 128Cs | 127.907749(6) | 3.640(14) min | ß+ to 128Xe | 1+ | N/A | 1065.52 | - |
| 129Cs | 128.906064(5) | 32.06(6) h | EC to 129Xe | 1/2+ | 1.49 | 1073.6 | - |
| 130Cs | 129.906709(9) | 29.21(4) min | EC to 130Xe; ß- to 130Ba | 1+ | 1.46 | 1081.68 | - |
| 131Cs | 130.905464(5) | 9.689(16) d | EC to 131Xe | 5/2+ | 3.54 | 1089.76 | - |
| 132Cs | 131.9064343(20) | 6.480(6) d | EC to 132Xe; ß- to 132Ba | 2+ | 2.22 | 1097.84 | - |
| 133Cs | 132.905451933(24) | STABLE | - | 7/2+ | 2.582024 | 1105.92 | 100 |
| 134Cs | 133.906718475(28) | 2.0652(4) y | EC to 134Xe; ß- to 134Ba | 4+ | 2.994 | 1114 | - |
| 135Cs | 134.9059770(11) | 2.3(3)E+6 y | ß- to 135Ba | 7/2+ | 2.732 | 1122.08 | - |
| 136Cs | 135.9073116(20) | 13.16(3) d | ß- to 136Ba | 5+ | 3.71 | 1130.15 | - |
| 137Cs | 136.9070895(5) | 30.1671(13) y | ß- to 137Ba | 7/2+ | 2.84 | 1138.23 | - |
| 138Cs | 137.911017(10) | 33.41(18) min | ß- to 138Ba | 3- | N/A | 1136.99 | - |
| 139Cs | 138.913364(3) | 9.27(5) min | ß- to 139Ba | 7/2+ | N/A | 1145.07 | - |
| 140Cs | 139.917282(9) | 63.7(3) s | ß- to 140Ba | 1- | N/A | 1153.15 | - |
| 141Cs | 140.920046(11) | 24.84(16) s | ß- to 141Ba; ß- + n to 140Ba | 7/2+ | N/A | 1151.91 | - |
| 142Cs | 141.924299(11) | 1.689(11) s | ß- to 142Ba; ß- + n to 141Ba | 0- | N/A | 1159.99 | - |
| 143Cs | 142.927352(25) | 1.791(7) s | ß- to 143Ba; ß- + n to 142Ba | 3/2+ | N/A | 1168.07 | - |
| 144Cs | 143.932077(28) | 994(4) ms | ß- to 144Ba; ß- + n to 143Ba | 1(-#) | N/A | 1166.83 | - |
| 145Cs | 144.935526(12) | 582(6) ms | ß- to 145Ba; ß- + n to 144Ba | 3/2+ | N/A | 1174.91 | - |
| 146Cs | 145.94029(8) | 0.321(2) s | ß- to 146Ba; ß- + n to 145Ba | 1- | N/A | 1173.68 | - |
| 147Cs | 146.94416(6) | 0.235(3) s | ß- to 146Ba; ß- + n to 147Ba | (3/2+) | N/A | 1181.75 | - |
| 148Cs | 147.94922(62) | 146(6) ms | ß- to 147Ba; ß- + n to 146Ba | N/A | N/A | 1189.83 | - |
| 149Cs | 148.95293(21)# | 150# ms [>50 ms] | ß- to 148Ba; ß- + n to 147Ba | 3/2+# | N/A | 1188.6 | - |
| 150Cs | 149.95817(32)# | 100# ms [>50 ms] | ß- to 149Ba; ß- + n to 148Ba | N/A | N/A | 1196.67 | - |
| 151Cs | 150.96219(54)# | 60# ms [>50 ms] | ß- to 150Ba; ß- + n to 149Ba | 3/2+# | N/A | 1195.44 | - |