the samples of an atom have the same mixture. Dalton also noted the law of multiple proportions, which is the second elements ratios of masses join with a given weight of the first element and can be decreased to small whole numbers in series of compounds. Thomas Thomson published Dalton’s theory in 1807 in the third edition of his System of Chemistry. He also published it in the Philosophical Transactions, a paper about strontium oxalates. Dalton published this himself a year later in a paper, the New System of Chemical Philosophy. The symbol Dalton used for calcium in his theory was a bigger, darker circle with a smaller, lighter circle inside of it. The element calcium is a hard, silver, and gray metal. It is the fifth most plentiful element in the Earth’s crust. Calcium makes up more than three percent of the crust. In nature it does not exist as the metal and is found in many minerals. Some of those minerals are gypsum (CaSO4.2H20), limestone (CaC03), and fluorite (CaF2). Apatite, which is a group of phosphate minerals with high concentrations of OH-, F-, Cl- ions in the crystal, is calcium fluorophosphate or chlorophosphate. Calcium carbonate (CaCO3) holds Stalagmites and Stalactites. That element is the fundamental principle of the cement production. Chemically classified, calcium is one of the alkaline elements. The element is quite reactive and makes a white coating of calcium nitride (Ca3N2) in the air. It reacts with water and the metal burns. While burning it has a yellow-red flame. The burning process mostly forms the nitride. The element calcium has the symbol Ca.
It has the atomic number twenty and the relative atomic mass of 40.078. The standard state of calcium, which means the reference point used to calculate the properties in different conditions, is solid at 298 K. This element is a silvery white and classified as metallic, which means it resembles a metal or metals. On the periodic table, the element calcium is located in group two. Group two is the alkaline earth metals, which means calcium is an alkaline earth metal. Also, on the periodic table it is located in period four. The block calcium is in is the s-block. The elements in the s-block are located in the first two periodic table groups. The electron shell structure for calcium are 2.8.8.2. For calcium, the CAS registry ID, which is a unique numerical identifier given to elements by the Chemical Abstracts Service, otherwise known as the CAS, is 7440-70-2. Calcium metal is now easily accessible commercially, so there is no need to make it in the laboratory. However, it can be made by the electrolysis of molten calcium chloride (CaCl2). Calcium chloride is manufactured by the action of hydrochloric acid upon calcium carbonate. In the Solway process used to make sodium carbonate, calcium chloride is a byproduct. Calcium can also be made through the reduction of CaO with aluminum or of CaCl2 with sodium
metal. The calcium isotopes, Ca-42, Ca-44, Ca-46, and Ca-48, are greatly used in clinical research and nutritional studies. They are all used to measure the calcium absorption mostly in children and women. Calcium deficiency is mostly related to increasing severity of osteoporosis in adults. On the other hand, calcium deficiency is essentially related to the development of rickets in children. In order to create super heavy elements, Ca-48 has been used to bombard Pb and Bi targets. In the past, calcium was used with sulfate (CaSO4), which was known as plaster of paris. The plaster of paris was useful for setting broken bones. Calcium was and still is the crucial constituent of leaves, bones, teeth, and shells. Today, calcium metal is used as a reducing agent in making other metals, such as thorium and uranium. For aluminum, beryllium, copper, lead, and magnesium alloys, calcium is used as an alloying agent. Calcium compounds are greatly used. Limestone which is calcium carbonate is used as a building stone and for cement. When the limestone is heated in kilns it leaves behind quicklime, calcium oxide, because it gave off carbon dioxide gas. The calcium oxide reacts with water to make slaked lime, which is calcium hydroxide. Slaked lime is also used to make cement. Its other uses are soil conditioner and treatment in water to decrease acidity. Other uses for slaked lime are to remove impurities from the molten iron ore in steelmaking. Slaked lime takes up carbon dioxide from the air and hardens as plaster when it is mixed with sand. The calcium element is also needed for animal and plant nutrition. It takes part in many biochemical reactions, which includes building skeletal systems and moderating muscle action. Some interesting facts about the element calcium are how it is spelled in other countries. Some other countries spell it the same way the United States does. Some of the countries that spell it Calcium are the United Kingdom, Germany, France, and the Netherlands. In the countries Italy and Spain it is spelled Calcio. In the country Portugal it is spelled similar to Italy and Spain, but it has an accent. So, in Portugal it is spelled Cálcio. Finally, in Sweden it is spelled Kalcium. Other interesting facts about the element calcium is that it is reactive. For a metal, calcium is soft. With a little bit of effort it can be cut with a sharp knife. When calcium comes into contact with air it makes a nitride and oxide coating to protect it from further corrosion. It is also interesting how when pure calcium metal is mixed with water it generates hydrogen gas vigorously. When calcium is in powder form and mixed with water it is quick and brutal as the surface area of the powder, which is increased, speeds up the reaction. Calcium is also a non-toxic element.