- Magnesium (Mg) is a lightweight, silvery-white alkaline earth metal with atomic number 12, positioned in Group 2 of the periodic table.
- It has two valence electrons in its outermost shell, giving it a stable +2 oxidation state in compounds.
- Its atomic structure consists of twelve protons, typically twelve neutrons, and twelve electrons arranged in three shells (two in the first shell, eight in the second, and two in the third).
- Magnesium has three stable isotopes: magnesium-24 (²⁴Mg), which makes up about 78.99% of natural magnesium; magnesium-25 (²⁵Mg), about 10.00%; and magnesium-26 (²⁶Mg), about 11.01%.
- Under standard conditions, magnesium is solid, has a low density, and exhibits a bright metallic luster that quickly dulls due to oxidation.
- Magnesium is the eighth most abundant element in Earth’s crust and the third most abundant dissolved element in seawater, after sodium and chlorine. It is produced in large amounts in stars through stellar nucleosynthesis, particularly during the fusion of helium and carbon in massive stars. On Earth, magnesium occurs primarily in minerals such as magnesite (MgCO₃), dolomite (CaMg(CO₃)₂), and in salts found in seawater and brines. Commercial magnesium is often extracted from seawater via the Dow process or from minerals through electrolysis of molten magnesium chloride (MgCl₂).
- The element was first recognized in 1755 by Scottish chemist Joseph Black, who distinguished magnesium from calcium. It was first isolated in 1808 by Sir Humphry Davy through the electrolysis of a mixture of magnesium oxide (MgO) and mercuric oxide (HgO). The name derives from “Magnesia,” a district in Thessaly, Greece, where magnesium-rich minerals were first studied.
- Magnesium is biologically essential, playing a crucial role in over 300 enzymatic reactions, particularly those involving ATP, the primary energy currency of cells. It is a central atom in the chlorophyll molecule, enabling plants to capture solar energy for photosynthesis. In humans and other animals, magnesium is vital for muscle function, nerve signaling, protein synthesis, and bone health. Dietary sources include green leafy vegetables, nuts, seeds, whole grains, and mineral water.
- Industrially, magnesium is valued for its low density and high strength-to-weight ratio, making it ideal for aerospace, automotive, and electronics applications. It is commonly alloyed with aluminum, zinc, and manganese to produce materials that are strong yet lightweight. Magnesium is also used in pyrotechnics, flares, and fireworks due to its brilliant white flame when burned, as well as in the production of iron and steel as a desulfurizing agent.
- Chemically, magnesium reacts slowly with cold water but more vigorously with hot water, forming magnesium hydroxide (Mg(OH)₂) and hydrogen gas. It reacts readily with acids, producing magnesium salts and releasing hydrogen. A thin oxide layer (MgO) forms on its surface in air, providing some protection against further oxidation, though it burns easily once ignited.
- While magnesium metal is flammable, magnesium compounds are generally safe and widely used in medicine, such as magnesium hydroxide (milk of magnesia) as an antacid and laxative, and magnesium sulfate (Epsom salt) for therapeutic baths. Excessive magnesium intake from supplements can cause adverse health effects, but dietary magnesium is generally considered beneficial for cardiovascular and neurological health.
