#24
Chromium
transition metal· Solid·51.99616 u
Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point.
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Identity
- Symbol
- Cr
- Atomic Number
- 24
- Atomic Mass
- 51.99616 u
- Category
- transition metal
- Block
- d-block
- Period
- 4
- Group
- 6
- Appearance
- silvery metallic
- Year Discovered
- 1797 CE
- Discovered By
- Louis Nicolas Vauquelin
- Named By
- color field
Electrons
- Configuration
- [Ar] 3d5 4s1
- Full Configuration
- 1s2 2s2 2p6 3s2 3p6 4s1 3d5
- Shells
- 2, 8, 13, 1
- Electronegativity
- 1.66
- Electron Affinity
- 65.21
- Oxidation States
- +6, +3, +2
- Ionization Energies
- 652.9, 1590.6, 2987, 4743, 6702 … +19 more
Physical Properties
- State at
- Solid
- Melting Point
- 2180
- Boiling Point
- 2944
- Density
- 7.19
- Molar Heat
- 23.35 J/(mol·K)
- Crystal Structure
- BCC
- Magnetic Ordering
- Antiferromagnetic
Mechanical
- Atomic Radius
- 166 pm
- Covalent Radius
- 139 pm
- Van der Waals
- 189 pm
- Metallic Radius
- 128 pm
- Mohs Hardness
- 8.5
- Brinell Hardness
- 1120 MPa MPa
- Vickers Hardness
- 1060 MPa MPa
- Bulk Modulus
- 160 GPa GPa
- Shear Modulus
- 115 GPa GPa
- Young's Modulus
- 279 GPa GPa
Thermal & Electrical
- Thermal Conductivity
- 93.9 W/(m K) W/(m·K)
- Electrical Conductivity
- 7.87 MS/m S/m
- Specific Heat
- 449 J/(kg K) J/(g·K)
- Heat of Vaporization
- 339 kJ/mol kJ/mol
- Heat of Fusion
- 21 kJ/mol kJ/mol
Abundance
- Universe
- 15 ppm
- Sun
- 20 ppm
- Meteorite
- 2600 ppm
- Earth's Crust
- 7.14 ppm
- Ocean
- 300 ppt
- Human Body
- 30.0 ppb