File: Phosphorescent pigment red. JPG | phosphorescent pigment red ( Calcium sulfide )

* Calcium sulfide ( CaS ), a chemical compound

* Calcium sulfide ( CaS ), a chemical compound

Calcium ( ) is the chemical element with symbol Ca and atomic number 20.

Calcium metal reacts with water, evolving hydrogen gas at a rate rapid enough to be noticeable, but not fast enough at room temperature to generate much heat.

Calcium, with a density of 1. 55 g / cm < sup > 3 </ sup >, is the lightest of the alkaline earth metals ; magnesium ( specific gravity 1. 74 ) and beryllium ( 1. 84 ) are more dense, although lighter in atomic mass.

Calcium is the fifth-most-abundant element by mass in the human body, where it is a common cellular ionic messenger with many functions, and serves also as a structural element in bone.

Calcium, combined with phosphate to form hydroxylapatite, is the mineral portion of human and animal bones and teeth.

Calcium carbonate is deposited where evaporation of the water leaves a solution supersaturated with the chemical constituents of calcite.

* Calcium levels in livestock feed are supplemented with it, such as for poultry ( when ground up ).

Calcium causes synaptic vesicles filled with neurotransmitter molecules to fuse with the membrane, releasing their contents into the synaptic cleft.

Calcium and vitamin D decrease the risk of non-vertebral fractures in those with postmenopausal osteoporosis by approximately 18 %.

Calcium carbonate is susceptible to even a weak acid solution because the crystals of calcium carbonate react with the acetic acid in the vinegar to form calcium acetate and carbon dioxide.

Calcium oxide, in the form of lime, was often used for this purpose, since it could react with the carbon dioxide and sulfur dioxide produced during roasting and smelting to keep them out of the working environment.

The skin is washed with water and lime ( Calcium hydroxide ), but not together.

Calcium phosphide is often used in naval flares, as in contact with water it liberates phosphine which self-ignites in contact with air ; it is often used together with calcium carbide which releases acetylene.

Calcium binds with available oxalate in the gastrointestinal tract, thereby preventing its absorption into the bloodstream, and reducing oxalate absorption decreases kidney stone risk in susceptible people.

Calcium citrate supplements can be taken with meals if dietary calcium cannot be increased by other means.

* Chicken soup revisited: Calcium content of soup increases with duration of cooking

Calcium channel blockers have been used to treat Alzheimer ’ s disease with some success, and the use of lithium to decrease IP < sub > 3 </ sub > turnover has also been suggested as a possible method of treatment.

At a breakage site in Rome, Testaccio, close to the Tiber, the fragments, later wetted with Calcium hydroxide ( Calce viva ), remained to create a hill now named Monte Testaccio, high and more than 1 km in circumference.

When the cement paste exposed to the air and meteoric water reacts with the atmospheric CO < sub > 2 </ sub >, portlandite and the Calcium Silicate Hydrate ( CSH ) of the hardened cement paste become progressively carbonated and the high pH gradually decreases from 13. 5 – 12. 5 to 8. 5, the pH of water in equilibrium with calcite ( calcium carbonate ) and the steel is no longer passivated.

Calcium channel blockers and losartan are associated with a lower risk of gout as compared to other medications for hypertension.

* Calcium, salt ( sodium and chloride ), magnesium, and potassium ( along with phosphorus and sulfur ) are sometimes added to the list of macronutrients because they are required in large quantities compared to other vitamins and minerals.

:: Beryllium ( Z = 4 ), Magnesium ( Z = 12 ), Calcium ( Z = 20 ), strontium ( Z = 38 ), Barium ( Z = 56 ), Radium ( Z = 88 ).

Calcium ion ( Ca < sup >++</ sup >) antagonists ( Calcium channel blockers ) are used in the treatment of chronic stable angina.

Calcium is essential for living organisms, in particular in cell physiology, where movement of the calcium ion Ca < sup > 2 +</ sup > into and out of the cytoplasm functions as a signal for many cellular processes.

Calcium salts are colorless from any contribution of the calcium, and ionic solutions of calcium ( Ca < sup > 2 +</ sup >) are colorless as well.

Calcium has four stable isotopes (< sup > 40 </ sup > Ca, < sup > 42 </ sup > Ca, < sup > 43 </ sup > Ca and < sup > 44 </ sup > Ca ), plus two more isotopes (< sup > 46 </ sup > Ca and < sup > 48 </ sup > Ca ) that have such long half-lives that for all practical purposes they also can be considered stable.

Calcium also has a cosmogenic isotope, radioactive < sup > 41 </ sup > Ca, which has a half-life of 103, 000 years.

* Calcium hydroxide solution ( Ca ( OH )< sub > 2 </ sub >) ( also known as limewater ) is used to detect the presence of carbon dioxide by being bubbled through a solution.

* Calcium arsenate ( Ca < sub > 3 </ sub >( AsO < sub > 4 </ sub >)< sub > 2 </ sub >) is used in insecticides.

* Calcium cyclamate ( Ca ( C < sub > 6 </ sub > H < sub > 11 </ sub > NHSO < sub > 3 </ sub >)< sub > 2 </ sub >) was used as a sweetening agent but is no longer permitted for use because of suspected cancer-causing properties.

* Calcium gluconate ( Ca ( C < sub > 6 </ sub > H < sub > 11 </ sub > O < sub > 7 </ sub >)< sub > 2 </ sub >) is used as a food additive and in vitamin pills.

* Calcium hypochlorite ( Ca ( OCl )< sub > 2 </ sub >) is used as a swimming pool disinfectant, as a bleaching agent, as an ingredient in deodorant, and in algaecide and fungicide.

* Calcium permanganate ( Ca ( MnO < sub > 4 </ sub >)< sub > 2 </ sub >) is used in liquid rocket propellant, textile production, as a water sterilizing agent and in dental procedures.

* Calcium phosphate ( Ca < sub > 3 </ sub >( PO < sub > 4 </ sub >)< sub > 2 </ sub >) is used as a supplement for animal feed, fertilizer, in commercial production for dough and yeast products, in the manufacture of glass, and in dental products.

* Calcium phosphide ( Ca < sub > 3 </ sub > P < sub > 2 </ sub >) is used in fireworks, rodenticide, torpedoes and flares.

* Calcium stearate ( Ca ( C < sub > 18 </ sub > H < sub > 35 </ sub > O < sub > 2 </ sub >)< sub > 2 </ sub >) is used in the manufacture of wax crayons, cements, certain kinds of plastics and cosmetics, as a food additive, in the production of water resistant materials and in the production of paints.

Calcium sulfoaluminate cements are made from clinkers that include ye ' elimite ( Ca < sub > 4 </ sub >( AlO < sub > 2 </ sub >)< sub > 6 </ sub > SO < sub > 4 </ sub > or C < sub > 4 </ sub > A < sub > 3 </ sub > in Cement chemist's notation ) as a primary phase.

* Calcium Ca < sup > 2 +</ sup >

Calcium ( Ca ) is in group 2, for it contains 2 valence electrons.