Ca

Calcium

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.

Group	alkaline earth metal
Atomic number	20
Period	4
Group	2
Phase (STP)	Solid
Atomic mass	40.0784
Density (STP)	1.55 g/L
Melting Point	1115 K
Molar heat capacity	25.929 J/(mol·K)
Boiling point	1757 K
Discovered by	Humphry Davy undefined
Named by
Protons	20
Neutrons	20
Electrons	20
Valencia electrons	2

https://en.wikipedia.org/wiki/Calcium