Magnesium (Mg)


  • Symbol: Mg
  • Atomic Number: 12
  • Atomic Weight: 24.305
  • Element Classification: Alkaline Earth Metal
  • Discovered By: Sir Humphry Davy
  • Discovery Date: 1808
  • Name Origin: Greek: ‘Magnesia’, a district in Thessaly
  • Density(g/cc): 1.738 (at 20°C)
  • Melting Point: 650°C
  • Boiling Point: 1090°C
  • Appearance: Shiny, silvery-white, lightweight metal
  • Atomic Radius(pm): 160


Magnesium was first isolated by Sir Humphry Davy in 1808, through the electrolysis of a mixture of magnesia (MgO) and mercuric oxide. Davy’s pioneering use of electrolysis to isolate elements underscored the chemical affinity between magnesium, calcium, and the alkaline earth metals. The name magnesium originates from Magnesia, a district in Thessaly, Greece, where magnesium-containing minerals were historically found.

Relation to Other Elements

Magnesium is part of the alkaline earth metals group in the periodic table, characterized by their two valence electrons. These metals are highly reactive, though less so than the alkali metals, and readily form divalent cations (Mg²⁺). Magnesium’s properties include a low density, high strength-to-weight ratio, and good resistance to corrosion due to the formation of a protective oxide layer. Its chemical behavior is somewhat similar to that of its group neighbors, particularly calcium, with which it shares many chemical and physical properties.

Natural Occurrence

Magnesium is the eighth most abundant element in the Earth’s crust and the third most abundant dissolved in seawater. It primarily occurs in minerals like dolomite (CaMg(CO₃)₂), magnesite (MgCO₃), and brucite (Mg(OH)₂), as well as in the chlorophyll molecules in green plants, which is crucial for photosynthesis. Magnesium ions are vital for all living cells, playing a key role in stabilizing structures of proteins and nucleic acids.


Magnesium has diverse applications across various fields:

  • Alloys: Due to its light weight and strength, magnesium is used in alloys with aluminum, which are essential in aerospace and automotive industries for reducing weight while maintaining structural integrity.
  • Chemical Reactions: Magnesium is a reagent in Grignard reactions in organic chemistry, enabling the formation of carbon-carbon bonds.
  • Fireworks and Flares: Magnesium burns with a bright white light, making it useful in fireworks, flares, and incendiary devices.
  • Medicine: Magnesium compounds like magnesium sulfate (Epsom salts) and magnesium hydroxide (milk of magnesia) are used for medicinal purposes, including laxatives and antacids.
  • Electronics: Magnesium is used in mobile phones, laptops, and other electronic devices for cases and components due to its lightweight properties.

The discovery of magnesium and the exploration of its properties and compounds have significantly impacted materials science, medicine, and technology, highlighting the importance of this lightweight metal in modern applications.


Sodium (Na)

Aluminum (Al)