  Calcium (Ca) is element number 20 on the periodic table. It is the fifth most abundant element in Earth's crust.
Calcium, an alkaline earth metal, is soft and silvery-white, although it quickly tarnishes in air and turns grayish white. When ignited, calcium metal burns with a white flame and a tinge of red. It reacts vigorously with water. Calcium is a soft, ductile metal that can be cut with a knife. It's denser than water. The most common calcium compound on Earth is calcium carbonate CaCO3, found in limestone and the fossilized remnants of early sea life. Corals, sea shells, and pearls are mostly made up of calcium carbonate. Calcium carbonate is used to treat heartburn, indigestion, upset stomach, and other conditions caused by too much stomach acid. It works by reducing the amount of acid in the stomach. It belongs to a group of medications called antacids. It may also be used to increase calcium levels in your body. 
Calcium is essential for the growth of healthy teeth and bones; calcium phosphate is a mineral that makes bones hard and strong.Dairy products are good sources of calcium, but so are leafy greens, almonds, broccoli, and canned fish. Osteoporosis is more likely to occur in people who have, among other things, habitual low calcium intake. |