20 - Calcium alkaline earth metal
Discovered by Humphry Davy in 1808
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.
H He Li Be B C N O F Ne Na Mg Al Si P S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
57-71 La-Lu Lanthanides
89-103 Ac-Lr Actinides
| 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 |
40.1 u Atomic Mass
2.2 Å Atomic Radius
1.76k 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
1.11k K Melting Point
4 Number of Shells
2 Electron Valency
20 Atomic Number
2, 8, 8, 2 Electron Shell Occupations
0.647 J/(g K) Specific Heat