Atomic number: 20

Symbol: Ca

Category: metal

Density at 25°C: solid

Another essential element to life, although more as an ion Ca2+ since the element itself tend to be very reactive. In life it is found in animal bones bound with phosphate.


Calcium sealed in argon filled tube. image: wikipedia

Use, natural applications or common combinations: 

  • Bones
  • Calcium carbonate, limestone
  • cement and mortar for building

Basic characteristics:

  • Standard atomic weight: 40.078(4)
  • Melting point: 842 °C
  • Boiling point: 1484 °C
  • Radioactivity:  most are stable
  • 45Ca is synthetic with a half life of 162.7 days