20 - Calcium alkaline earth metal
Discovered by Humphry Davy in 1808
- Atomic Radius (Å)
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.
| Shell | Electrons | Orbitals |
|---|---|---|
| 1 | 2 | 2 in 1s |
| 2 | 8 | 2 in 2s + 6 in 2p |
| 3 | 8 | 2 in 3s + 6 in 3p |
| 4 | 2 | 2 in 4s |
40.08 u
Atomic Mass
2.2 Å
Atomic Radius
1757 K
Boiling Point
1.76 Å
Covalent Radius
1.55 g/cm³
Density
2.37
Electron Affinity
1
Electronegativity
6.11 eV
First Ionization Energy
1112.15 K
Melting Point
4
Number of Shells
2
Electron Valency
20
Atomic Number
2, 8, 8, 2
Electron Shell Occupations
0.65 J/(g K)
Specific Heat
