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20Ca40.078
Calcium
Alkaline Earth MetalCalcium 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.
Phase: Solid
2, 8, 8, 2
Physical Properties
Atomic Mass40.0784 u
Density1.55 g/cm³
Melting Point1115 K
Boiling Point1757 K
Molar Heat25.929 J/(mol·K)
Period4
PhaseSolid
Chemical Properties
Electron Configuration1s2 2s2 2p6 3s2 3p6 4s2
Semantic Config[Ar] 4s2
Shells2, 8, 8, 2
Electron Affinity2.37 kJ/mol
Electronegativity1
Ionization Energies
IE1: 589.8 kJ/molIE2: 1145.4 kJ/molIE3: 4912.4 kJ/molIE4: 6491 kJ/molIE5: 8153 kJ/molIE6: 10496 kJ/molIE7: 12270 kJ/molIE8: 14206 kJ/molIE9: 18191 kJ/molIE10: 20385 kJ/molIE11: 57110 kJ/molIE12: 63410 kJ/molIE13: 70110 kJ/molIE14: 78890 kJ/molIE15: 86310 kJ/molIE16: 94000 kJ/molIE17: 104900 kJ/molIE18: 111711 kJ/molIE19: 494850 kJ/molIE20: 527762 kJ/mol
Discovery
Discovered byHumphry Davy