Chemical Fact Sheet
Calcium
| Chemical Abstract Number (CAS #) | 7440-70-2 |
|---|---|
| Analytical Methods | 200.7 - 200.8 - 6010 - 6020 |
| Molecular Formula | Ca |
|
Synopsis
|
Calcium - (L. calx, lime), Ca; at. wt. 40.078(4); at. no. 20; m.p. 842 +/- 2 deg C; b.p. 1484 deg C; sp. gr. 1.55 (20 deg C); valence 2. Though lime was prepared by the Romans in the first century under the name calx, the metal was not discovered until 1808. After learning that Berzelius and Pontin prepared calcium amalgam by electrolyzing lime in mercury, Davy was able to isolate the impure metal. Calcium is a metallic element, fifth in abundance in the earth's crust, of which it forms more than 3%. It is an essential constituent of leaves, bones, teeth, and shells. Never found in nature uncombined, it occurs abundantly as limestone (CaC03), gypsum (CaSO4-2H20), and fluorite (CaF2); apatite is the fluorophosphate or chlorophosphate of calcium. The metal has a silvery color, is rather hard, and is prepared by electrolysis of the fused chloride to which calcium fluoride is added to lower the melting point. Chemically it is one of the alkaline earth elements; it readily forms a white coating of nitride in air, reacts with water, burns with a yellow-red flame, forming largely the nitride. The metal is used as a reducing agent in preparing other metals such as thorium, uranium, zirconium, etc., and is used as a deoxidizer, desulfurizer, or decarburizer for various ferrous and nonferrous alloys. It is also used as an alloying agent for aluminum, beryllium, copper, lead, and magnesium alloys, and serves as a "getter" for residual gases in vacuum tubes, etc. Its natural and prepared compounds are widely used. Quicklime (CaO), made by heating limestone and changed into slaked lime by the careful addition of water, is the great cheap base of chemical industry with countless uses. Mixed with sand it hardens as mortar and plaster by taking up carbon dioxide from the air. Calcium from limestone is an important element in Portland cement. The solubility of the carbonate in water containing carbon dioxide causes the formation of caves with stalactites and stalagmites and is responsible for hardness in water. Other important compounds are the carbide (CaC2), chloride (CaCl2), cyanamide (CaCN2), hypochlorite (Ca(OCl)2), nitrate (Ca(NO3)2), and sulfide (CaS). Natural calcium contains six isotopes. Thirteen other radioactive isotopes are known. Metallic calcium (99.5%) costs about $200/kg. |
| Apparent Color | LUSTROUS, SILVER-WHITE SURFACE (WHEN FRESHLY CUT); FACE-CENTERED CUBIC STRUCTURE BELOW 300 DEG C; ACQUIRES BLUISH-GRAY TARNISH ON EXPOSURE TO MOIST AIR |
| Boiling Point | 1440 DEG C |
| Melting Point | 850 DEG C |
| Molecular Weight | 40.08 |
| Density | 1.54 @ 20 DEG C/4 DEG C |
| Sensitivity Data | SOLID MATERIAL WILL CAUSE SKIN & EYE BURNS SINCE IT REACTS WITH MOISTURE TO FORM CAUSTIC. |
|
Chemical and Physical Properties |
DECOMP IN WATER MUCH HARDER THAN SODIUM, BUT SOFTER THAN ALUMINUM OR MAGNESIUM; BRINELL HARDNESS: 17; ELECTRICAL RESISTIVITY: 3.5 MICROOHM CM @ 20 DEG C; SPECIFIC HEAT: 0.149 CAL/G (FROM 0-100 DEG C); REACTS WITH WATER, ALCOHOLS, DIL ACIDS & HALOGENS; FORMS BLUE COLOR IN LIQUID AMMONIA ALKALINE EARTH ELEMENT; OXIDIZES IN AIR TO FORM ADHERENT PROTECTIVE FILM; CAN BE MACHINED, EXTRUDED, OR DRAWN BURNS WITH CRIMSON FLAME. |
|
Environmental Fate |
FORMS: CROWNS, NODULES, INGOTS, CRYSTALS UP TO 99% PURE. OCCURRENCE IN EARTH'S CRUST 3.64%. SEA WATER CONTAINS APPROXIMATELY 400 G/TON. FOUND NATURALLY ONLY IN FORM OF ITS COMPD, NEVER UNCOMBINED ESSENTIAL CONSTITUENT OF BONES, SHELLS, TEETH. CALCIUM IS 5TH MOST ABUNDANT ELEMENT & 3RD MOST ABUNDANT METAL; IT IS WIDESPREAD IN NATURE AS CALCIUM CARBONATE (LIMESTONE & MARBLE), CALCIUM SULFATE (GYPSUM), CALCIUM FLUORIDE (FLUORSPAR) & CALCIUM PHOSPHATE (APATITE). |
|
Drinking Water Impact |
The solute and particulate calcium (Ca) chemistry of a relatively unpolluted snowfall associated with a maritime airmass was measured by neutron activation analysis (NAA) and inductively-coupled plasma analysis (soluble fraction) and NAA (particulate material), to characterize background conditions for the Scottish Highlands. Ca concentrations were compared to those found in a polluted black snowfall with a trajectory that originated over eastern Europe and to those levels found in seasonal snowpack. The variability of the concentration of solute and the chemical composition of particulate material is reported on an intra-and inter-site basis. The solute Ca content of Scottish snowfall in the inter-site survey was 419 ug/l, and in the intra-site survey 310 ug/l. The Ca composition of particulate matter found within Scottish snow was 2,400 ppm in the inter-site survey, and 2,160 ppm in the intra-site survey. For the black snow, the solute Ca content was 630 +/- 50ug/l, and the Ca composition of particulate matter was 3,530. The mean concentration of Ca in seasonal snowpack was 2,500 ppm. |
 |
Alphabetical List of Compounds |
 |
List of Compounds by CAS Number |
 |
List of Services |
 |
Spectrum Laboratories Homepage |
