Magnesium
chemical element, symbol Mg and atomic number 12 / From Wikipedia, the free encyclopedia
Magnesium ( /mæɡˈniːziəm/ mag-NEE-zee-əm) is a chemical element with the symbol Mg, atomic number 12 and common oxidation state +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust, where it constitutes about 2% by mass, and ninth in the known universe as a whole.[7] This is because it is easily built up in supernova stars by addition of three helium nuclei to carbon (which in turn is made from three helium nuclei). Magnesium ion's high solubility in water helps ensure that it is the third most abundant element dissolved in seawater.[8]
Magnesium is the 11th most abundant element by mass in the human body. Its ions are essential to all living cells. The ions play a major role in manipulating important biological polyphosphate compounds like ATP, DNA, and RNA. Hundreds of enzymes thus require magnesium ions to function. Magnesium is also the metallic ion at the center of chlorophyll. It is a common additive to fertilizers.[9] Magnesium ions are sour to the taste, and in low concentrations help to impart a natural tartness to fresh mineral waters.
The free element (metal) is not found naturally on Earth, as it is highly reactive (though once produced, it is coated in a thin layer of oxide (see passivation), which partly masks this reactivity). The free metal burns with a brilliant white light, making it a useful ingredient in flares. The metal is now mainly obtained by electrolysis of magnesium salts obtained from brine.