#55
Cesium
alkali metal· Solid·132.905451966 u
Caesium or cesium is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C (82 °F), which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium is an alkali metal and has physical and chemical properties similar to those of rubidium and potassium.
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Identity
- Symbol
- Cs
- Atomic Number
- 55
- Atomic Mass
- 132.905451966 u
- Category
- alkali metal
- Block
- s-block
- Period
- 6
- Group
- 1
- Appearance
- silvery gold
- Year Discovered
- 1860 CE
- Discovered By
- Robert Bunsen
- Named By
- sky blue
Electrons
- Configuration
- [Xe] 6s1
- Full Configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s1
- Shells
- 2, 8, 18, 18, 8, 1
- Electronegativity
- 0.79
- Electron Affinity
- 45.505
- Oxidation States
- +1
- Ionization Energies
- 375.7, 2234.3, 3400
Physical Properties
- State at
- Solid
- Melting Point
- 301.7
- Boiling Point
- 944
- Density
- 1.93
- Molar Heat
- 32.21 J/(mol·K)
- Crystal Structure
- BCC
- Magnetic Ordering
- Paramagnetic
Mechanical
- Atomic Radius
- 298 pm
- Covalent Radius
- 244 pm
- Van der Waals
- 343 pm
- Metallic Radius
- 265 pm
- Mohs Hardness
- 0.2
- Brinell Hardness
- 0.14 MPa MPa
- Bulk Modulus
- 1.6 GPa GPa
- Shear Modulus
- 0.58 GPa GPa
- Young's Modulus
- 1.7 GPa GPa
Thermal & Electrical
- Thermal Conductivity
- 35.9 W/(m K) W/(m·K)
- Electrical Conductivity
- 4.8 MS/m S/m
- Specific Heat
- 242 J/(kg K) J/(g·K)
- Heat of Vaporization
- 63.9 kJ/mol kJ/mol
- Heat of Fusion
- 2.09 kJ/mol kJ/mol
Abundance
- Universe
- 800 ppt
- Sun
- 8 ppb
- Meteorite
- 140 ppb
- Earth's Crust
- 3 ppm
- Ocean
- 300 ppt
- Human Body
- 20.0 ppb