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 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.

Calcium has a higher electrical resistivity than copper or aluminium, yet weight-for-weight, due to its much lower density, it is a rather better conductor than either.

Calcium to phosphorus ratios should be 2: 1 to prevent hypocalcemia, sometimes known as hind leg paralysis ( HLP ).

* Marshmallows ( Sugar, Modified Corn Starch, Corn Syrup, Dextrose, Gelatin, Calcium Carbonate, Yellow 5 & 6, Blue 1, Red 40 )

Calcium hydroxide, Ca ( OH )< sub > 2 </ sub > is sparsely soluble in water ( 1. 5 g dm < sup >- 3 </ sup > at 25 ° C.

in other words, each 1 g / dL decrease of albumin will decrease 0. 8 mg / dL in measured serum Ca and thus 0. 8 must be added to the measured Calcium to get a corrected Calcium value.

* Wax Nails ( 1 Get Your Calcium, 2 Cereal Killer, 3 Seed, 4 The Crawling Backward Man, 5 In Good Hands, 6 How's Your House?

Carbonated water, High fructose corn syrup and / or Sugar, Citric acid, natural and artificial flavors, Phosphoric acid, Potassium citrate, Potassium benzoate and Potassium sorbate ( to preserve freshness ), Caffeine, Gum arabic, Ascorbic acid and Calcium disodium EDTA ( to protect flavor ), blue 1, red 40.

Calcium phosphate ( phosphate rock ) is heated to 1, 200 – 1, 500 ° C with sand, which is mostly, and coke ( impure carbon ) to produce.

Calcium, phosphorus and iron are present in worthwhile amounts, and eleven other minerals also have been found in varying trace amounts.

Calcium and sodium lactate.

Calcium hydride was substituted for Af as a drying agent for carbon tetrachloride.

Calcium has been added to over-the-counter products, which contributes to inadvertent excessive intake.

Calcium salts may cause constipation.

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

Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust.

Calcium is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate.

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 hydroxide ( slaked lime ) is used in many chemical refinery processes and is made by heating limestone at high temperature ( above 825 ° C ) and then carefully adding water to it.

Calcium carbonate ( CaCO < sub > 3 </ sub >) is one of the common compounds of calcium.

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 isotope fractionation during mineral formation has led to several applications of calcium isotopes.