#81
Thallium
post-transition metal· Solid·204.38 u
Thallium is a chemical element with symbol Tl and atomic number 81. This soft gray post-transition metal is not found free in nature. When isolated, it resembles tin, but discolors when exposed to air.
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Identity
- Symbol
- Tl
- Atomic Number
- 81
- Atomic Mass
- 204.38 u
- Category
- post-transition metal
- Block
- p-block
- Period
- 6
- Group
- 13
- Appearance
- silvery white
- Year Discovered
- 1861 CE
- Discovered By
- William Crookes
- Named By
- thallus
Electrons
- Configuration
- [Xe] 4f14 5d10 6s2 6p1
- Full Configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p1
- Shells
- 2, 8, 18, 32, 18, 3
- Electronegativity
- 1.62
- Electron Affinity
- 36.4
- Oxidation States
- +3, +1
- Ionization Energies
- 589.4, 1971, 2878
Physical Properties
- State at
- Solid
- Melting Point
- 577
- Boiling Point
- 1746
- Density
- 11.85
- Molar Heat
- 26.32 J/(mol·K)
- Crystal Structure
- HEX
- Magnetic Ordering
- Diamagnetic
Mechanical
- Covalent Radius
- 145 pm
- Van der Waals
- 196 pm
- Metallic Radius
- 170 pm
- Mohs Hardness
- 1.2
- Brinell Hardness
- 26.4 MPa MPa
- Bulk Modulus
- 43 GPa GPa
- Shear Modulus
- 2.8 GPa GPa
- Young's Modulus
- 8 GPa GPa
Thermal & Electrical
- Thermal Conductivity
- 46.1 W/(m K) W/(m·K)
- Electrical Conductivity
- 6.17 MS/m S/m
- Specific Heat
- 129 J/(kg K) J/(g·K)
- Heat of Vaporization
- 165 kJ/mol kJ/mol
- Heat of Fusion
- 4.14 kJ/mol kJ/mol
Abundance
- Universe
- 500 ppt
- Sun
- 1 ppb
- Meteorite
- 2 ppb
- Earth's Crust
- 850 ppb
- Ocean
- 6.50 ppt
- Human Body
- 50 ppt