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 =Calcium = toc

Classification:

 * Calcium is an Alkaline-Earth metal.

The History of Calcium:

 * In the first century, it was used in many different compounds by the ancient Romans, but it wasn't until 1808 that it was isolated by an English Chemist, Sir Humphry Davy.
 * Calcium was first found and isolated in England.
 * Calcium is the fifth most abundant element in the earth's crust, making up around 3.5% of the earth's crust, so it is found nearly everywhere.

Physical Properties:
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 * The melting point of Calcium is 893 degrees Celcius, and its freezing point is not definite.
 * The boiling point for Calcium is 1484 degrees Celcius.
 * Calcium has a silvery-white color.
 * Calcium naturally appears as a silvery-white and relatively soft element.
 * Calcium has 20 protons, neutrons, and electrons. Its atomic mass is 40.
 * The crystal structure for Calcium is cubic.
 * The density of Calcium is 1.55 g/cm3

Quick Facts:

 * Calcium is a solid at earth temperatures.
 * Calcium is very common on Earth.
 * Calcium has 24 isotopes, and 21 of them are radioactive.
 * Calcium has innumerable uses in different compounds. For example, calcium in limestone is an invaluable resource for Portland Cement. Calcium oxide is often used by the chemical industry because it is cheap and abundant. Despite these uses of calcium, it is mainly used as a nutrient that we intake to keep our bones and teeth healthy. In an average adult, over one kilogram of calcium is found in his or her body, and most of it is found in the teeth or bones.
 * The cost of calcium is 0.11 dollars per gram.
 * Calcium is derived from the Latin word //calcis//, meaning "lime."The man who isolated Calcium, Sir Humphry Davy, also contributed to the discoveries of chlorine and iodine. He is credited with discovering most of the alkalai and alkaline-earth metalsas well. Furthermore, he invented the Davy Lamp, which allowed miners to enter gassy workings.
 * Calcium can be found mostly in marble, limeston, and chalk.

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References:
> . > visualelements/pages/data/calcium_data.html>. > . > . > Elsevier, 2003.
 * Bentor, Yinon. "Calcium." __Chemical Elements__. 16 Nov. 2008
 * "Calcium-Ca." __Visual Elements__. 16 Nov. 2008 <http://www.rsc.org/chemsoc/
 * Donatelle, Rebecca. "Calcium." __Wikipedia__. 16 Nov. 2008
 * Gagnon, Steve. "Calcium." __Jefferson Lab__. 16 Nov. 2008
 * Saunders, Nigel. __Calcium and the Alkaline Earth Metals__. Chicago,Illinois: Reed