#20
Calcium
alkaline earth metal· Solid·40.0784 u
Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft gray alkaline earth metal, fifth-most-abundant element by mass in the Earth's crust. The ion Ca2+ is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate.
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Identity
- Symbol
- Ca
- Atomic Number
- 20
- Atomic Mass
- 40.0784 u
- Category
- alkaline earth metal
- Block
- s-block
- Period
- 4
- Group
- 2
- Appearance
- Chemical element with atomic number 20 (Ca)
- Year Discovered
- 1808 CE
- Discovered By
- Humphry Davy
- Named By
- lime
Electrons
- Configuration
- [Ar] 4s2
- Full Configuration
- 1s2 2s2 2p6 3s2 3p6 4s2
- Shells
- 2, 8, 8, 2
- Electronegativity
- 1
- Electron Affinity
- 2.37
- Oxidation States
- +2
- Ionization Energies
- 589.8, 1145.4, 4912.4, 6491, 8153 … +15 more
Physical Properties
- State at
- Solid
- Melting Point
- 1115
- Boiling Point
- 1757
- Density
- 1.55
- Molar Heat
- 25.929 J/(mol·K)
- Crystal Structure
- FCC
- Magnetic Ordering
- Diamagnetic
Mechanical
- Atomic Radius
- 194 pm
- Covalent Radius
- 176 pm
- Van der Waals
- 231 pm
- Metallic Radius
- 197 pm
- Mohs Hardness
- 1.75
- Brinell Hardness
- 167 MPa MPa
- Bulk Modulus
- 17 GPa GPa
- Shear Modulus
- 7.4 GPa GPa
- Young's Modulus
- 20 GPa GPa
Thermal & Electrical
- Thermal Conductivity
- 201 W/(m K) W/(m·K)
- Electrical Conductivity
- 28200000 S/m S/m
- Specific Heat
- 647 J/(kg K) J/(g·K)
- Heat of Vaporization
- 155 kJ/mol kJ/mol
- Heat of Fusion
- 8.54 kJ/mol kJ/mol
Abundance
- Universe
- 70 ppm
- Sun
- 70 ppm
- Meteorite
- 1.10%
- Earth's Crust
- 4.15%
- Ocean
- 412 ppm
- Human Body
- 1.40%