Nat Turner led a slave revolt several years before the Civil War. The revolt failed and he was killed. he is known for leading 2 uprises in Virginia in 1831 before getting caught.
Calcium (Ca), chemical element, one of the alkaline-earth metals of Group 2 (IIa) of the periodic table. It is the most abundant metallic element in the human body and the fifth most abundant element in Earthâs crust.
Smart Calcium Facts. 1  Calcium, the fifth most common element in the body, exists almost entirely (99%) as crystalline hydroxyapatite in bones and teeth. 2  Calcium is used by nerve cells to propagate an impulse, and by muscle cells to contract.