- Calcium is a chemical element with the symbol Ca and an atomic number of 20.
- The name calcium comes from the Latin word calx which means lime.
- Of all elements in the Earth's crust Calcium is the 5th most abundant. It makes up just over 3% of soil, air and oceans.
- Calcium is not naturally found in its elemental state but calcium compounds are common.
- Calcium compounds are most commonly found in sedimentary rocks such as limestone, chalk and marble where calcium carbonate minerals such as calcite and dolomite are present. Check out our calcium carbonate facts for more information.
- Calcium is also found in other minerals such as gypsum (calcium sulfate) and fluorite (calcium fluoride) and it occurs to a lesser extent in igneous and metamorphic rocks, mainly in silicate minerals.
- The element must be extracted using electrolysis. Once purified into a soft silvery-white metal calcium is reactive, it will rapidly form a gray-white oxide and nitride coating when exposed to air.
- Pure calcium metal reacts quite vigorously with water generating hydrogen gas.
- In powdered form, the reaction with water is extremely rapid and quite violent as the increased surface area of the powder accelerates the reaction.
- In the first century the Romans were preparing lime as calcium oxide but they did not recognize it as a metal.
- Calcium was not isolated as a metal until 1808 when Englishman Sir Humphry Davy electrolyzed a mixture of lime and mercuric oxide. Swedish chemists Berzelius and Pontin had created an amalgam of calcium by electrolyzing lime in mercury. Using their amalgam idea, Davy managed to isolate pure calcium metal.
- Calcium has a melting point of 1,548 °F (842 °C) and a boiling point of 2,703 °F (1,484 °C).
- Calcium is found in the human body as calcium ions, it is not present in its element form. It is the 5th most abundant element in our bodies. About one third of the mass of the human body is calcium after all water is removed.
- Calcium is very important for the human body. 99% of the body's calcium is stored in the bones and teeth, helping to strengthen them. The other 1% helps with muscle movement allowing nerves to carry messages between the brain and our body parts. It helps blood vessels move blood around and assists with the release of hormones and enzymes.
- We mainly get our body's calcium requirements through food. Vitamin D is needed to absorb this calcium. As a mineral, calcium is found in many foods, especially in dairy products such as milk, yogurt, and cheese. Vegetables like as broccoli, kale, and spinach are also high in calcium.
- Calcium compounds are used in the making of cement, glass, lime, bricks, paint, paper, sugar, removing non-metallic impurities from alloys, and as a reduction agent in the preparation of other metals.
- Calcium salts are used to produce a deep orange color in fireworks.