THE MAGNESIUM ELEMENT

The Magnesium Element



The Magnesium Element

Introduction

Magnesium, element number 12, is a hard, lustrous, silvery metal with a density of 1.74 g/cm3; it is one of the most widely distributed elements on Earth, ranking number 7 in relative abundance. Like the other alkaline earths, the pure element is never found in nature, and all magnesium compounds are in the form of the Mg2+ ion. There are two major sources of magnesium: seawater and the mineral magnesite (MgCO3). In the production of sodium chloride (table salt, NaCl), when seawater is allowed to evaporate, magnesium salts can be recovered along with the sodium salts. Magnesite, found in the United States mainly in Colorado, is also a common source of magnesium. Magnesium is essential to both plants and animals as a component of chlorophyll in green plants, bones in animals, and numerous enzymes in a variety of living organisms. In addition, magnesium helps build proteins and facilitates DNA replication.

Discussion

The magnesium ion (Mg2+) is an essential component of all living systems; it is the second most abundant positive ion within cells and the fourth most common cation in the body. Magnesium plays a structural role in bones and teeth. More importantly, magnesium ion is involved in a variety of cellular biochemical processes. Intracellular magnesium ion either is present in its free form or is bound to biomolecules such as adenosine triphosphate (ATP), nucleic acids, chlorophyll, and Mg2+-activated enzymes (Willett, 2007, Pp.N.D).

The bound form of intracellular magnesium ion predominates over its free from because of the high charge density of this metal ion. The partitioning of intracellular magnesium ion between bound and free forms regulates the biological activity of many Mg2+-dependent enzymes, which participate in glycolysis, muscle contraction, ion transport, protein synthesis, respiration, photosynthesis, and signal transduction. The free intracellular magnesium ion concentration, unlike that of the calcium ion (Ca2+), is well maintained within the cell; it has therefore been suggested that magnesium ion is not a trigger of cell activity but a static regulator (Stwertka, 2002, pp. 48).

The Astrophysics of Magnesium

The mechanisms by which magnesium is synthesized in stars depend on stellar properties such as mass, temperature, and density. In stars massive enough that the core reaches a temperature where carbon burning (the fusion of two carbon atoms) can occur, two different magnesium isotopes, 23Mg and 24Mg, can result from the following reactions:

Where n represents a neutron and ? a high-energy photon. Carbon burning can also produce oxygen nuclei, which, if the star uses up all the lighter elements in its core, can subsequently fuse to form magnesium 24:

where a represents an alpha particle or helium nucleus. This proceeds only in very massive stars where the central density can rise to at least 1010 kg/m3 (Willett, 2007, pp47).

The end of life for these stars is cataclysmic, but not as completely destructive as a supernova explosion. A star four to eight times as massive as the Sun typically supports not only a carbon-burning core, but also a helium-burning layer as well as a hydrogen-burning ...