Number of Protons: 20
Number of Neutrons: 20
Number of Electrons: 20
Solid, liquid, or gas? : Solid
Classification: Alkali Earth Metal
Calcium was discovered by Sir Humphrey Davy in 1808 at England.
Calcium compounds are widely used. There are vast deposits of limestone (calcium carbonate) used directly as a building stone and indirectly for cement. When limestone is heated in kilns it gives off carbon dioxide gas leaving behind quicklime (calcium oxide). This reacts vigorously with water to give slaked lime (calcium hydroxide). Slaked lime is used to make cement, as a soil conditioner and in water treatment to reduce acidity, and in the chemicals industry. It is also used in steel making to remove impurities from the molten iron ore. When mixed with sand, slaked lime takes up carbon dioxide from the air and hardens as lime plaster. Gypsum (calcium sulfate) is used by builders as a plaster and by nurses for setting bones, as ‘plaster of Paris’.
Melting point 839° C
Boiling point 1484° C
Density 1.54 g/cm³
Oxidation- used as a deoxidizer in steel
Flammability: when heated in air or in oxygen it ignites
Compounds include: limestone, marble, and gypsum
Interesting Facts about Calcium
- Calcium is the most abundant of the metallic elements in the human body. The average adult body contains about 1 kg or 2 lb of calcium, 99% of which is in the bones and teeth. Only oxygen, carbon, hydrogen and nitrogen are more abundant in our bodies than calcium.
- Calcium not only builds the structures that support our bodies, many of us also live in homes built using structural concrete or cement made with lime (calcium oxide). Snails and many shellfish use another calcium compound – calcium carbonate – to build their own homes too – their shells.
- Modern humans were not the first people to make use of calcium to build things. Egypt’s pyramids were built using limestone blocks. Limestone is crystalline calcium carbonate. In the later pyramids, the blocks were held together with gypsum or lime based mortar. Gypsum is calcium sulfate dihydrate and lime is calcium oxide.
- Have you ever wanted to be ‘in the limelight?’ Lime is calcium oxide, which produces a brilliant, intense light when burnt in an oxyhydrogen flame. It was used to light the stage in theaters during the 1800s until electricity took over – hence the saying.
- Cells in animals and plants must communicate with other cells. This is called signaling. Calcium ions are the most important messengers between cells in living things and are absolutely vital for the existence of multicellular life forms.
- Calcium is used to remove oxygen, sulfur and carbon from alloys.
- Cost, pure: $20 per 100g
- It is used in the manufacture of other metals such as uranium and thorium.
- Abundance solar system: 70 parts per million by weight, 2 parts per million by moles.
- Calcium reacts easily with water and acids and the metal burns brightly in air, forming mainly the nitride.
- Calcium has 19 Isotopes whose half-lives are known, with mass numbers 35 to 53.
- It is a silvery-gray color.