Calcium

20
Ca
Group
2
Period
4
Block
s
Protons
Electrons
Neutrons
20
20
20
General Properties
Atomic Number
20
Atomic Weight
40.078
Mass Number
40
Category
Alkaline earth metals
Colour
Silver
Radioactive
No
From the Latin word calx, lime
Crystal Structure
Face Centered Cubic
History
Calcium was known as early as the first century when the Ancient Romans prepared lime as calcium oxide.

Calcium was first isolated by Sir Humphry Davy in 1808 when he electrolyzed a mixture of lime and mercuric oxide.

Davy was trying to isolate calcium; when he heard that Jöns Jakob Berzelius and Pontin prepared calcium amalgam by electrolyzing lime in mercury, he tried it himself.
Electrons per shell
2, 8, 8, 2
Electron Configuration
[Ar] 4s2
Ca
The shell of an egg is made up of primarily calcium carbonate
Physical Properties
Phase
Solid
Density
1.54 g/cm3
Melting Point
1115.15 K | 842 °C | 1547.6 °F
Boiling Point
1757.15 K | 1484 °C | 2703.2 °F
Heat of Fusion
8.54 kJ/mol
Heat of Vaporization
155 kJ/mol
Specific Heat Capacity
0.647 J/g·K
Abundance in Earth's crust
5%
Abundance in Universe
0.007%
Pure
Image Credits: Wikimedia Commons (Matthias Zepper)
Pure calcium in a protective argon gas atmosphere
CAS Number
7440-70-2
PubChem CID Number
5460341
Atomic Properties
Atomic Radius
197 pm
Covalent Radius
176 pm
Electronegativity
1.00 (Pauling scale)
Ionization Potential
6.1132 eV
Atomic Volume
29.9 cm3/mol
Thermal Conductivity
2.01 W/cm·K
Oxidation States
1, 2
Applications
Calcium is used to remove oxygen, sulphur and carbon from alloys.

It is also used as an alloying agent used in the production of aluminium, beryllium, copper, lead, and magnesium alloys.

Calcium is used as a reducing agent in the extraction of other metals, such as uranium, zirconium, and thorium.

Calcium carbonate is used in manufacturing cement and mortar, lime and limestone.
Calcium is considered to be non-toxic
Isotopes
Stable Isotopes
40Ca, 42Ca, 43Ca, 44Ca, 46Ca
Unstable Isotopes
34Ca, 35Ca, 36Ca, 37Ca, 38Ca, 39Ca, 41Ca, 45Ca, 47Ca, 48Ca, 49Ca, 50Ca, 51Ca, 52Ca, 53Ca, 54Ca, 55Ca, 56Ca, 57Ca