Calcium Chemicals and materials Calcium is a soft, silvery white metal. It doesn’t occur naturally in pure form. In compounds, calcium is the fifth most abundant element on the Earth. Calcium is one of six alkaline-earth metals.
Slaked lime is calcium hydroxide. It may be called `slaked’ because it slakes (quenches) a plant’s thirst for lime in acid soils.
Most calcium compounds are white solids called limes. They include chalk, porcelain, tooth enamel, cement, seashells, the limescale on taps.
The word `lime’ comes from the Latin word for ‘slime.
Quicklime is calcium oxide. It is called ‘quick’ (Old English for ‘living’) because when water drips on it, it twists and swells as if it is alive. A Calcium is one of the basic building materials of living things. It is one of the crucial ingredients in shell, such as those on crabs, and bone, which is why they are typically white.
Calcium has an atomic number of 20. It has a melting point of 839°C and a boiling point of 1484°C.
Limelight was the bright light used by theatres in the days before electricity. It was made by applying a mix of oxygen and hydrogen to pellets of calcium.
Calcium adds rigidity to bones and teeth and helps to control muscles. Your body gets it from milk and cheese. Milk and its products, such as butter and cheese, are key sources of calcium. Green vegetables are another important source.
Calcium is essential to human beings. It is vital for the growth and maintenance of the bones and teeth, and it also helps the blood to clot and the muscles to contract.