Magnesium is a reactive alkaline earth metal (Group 2). Oxygen is a highly reactive nonmetal gas involved in combustion and oxidation reactions. When combined, a highly energetic chemical reaction occurs. This reaction results in a single, stable compound, demonstrating how a metal and a nonmetal form a new substance.
The Resulting Compound: Magnesium Oxide
The product of the reaction is magnesium oxide (MgO), commonly known as magnesia. This metal oxide typically presents as a fine, white, odorless powder.
Magnesium oxide is classified as a basic oxide because it reacts with water to form magnesium hydroxide, a weak base. Its exceptional thermal stability is a notable physical property, featuring a very high melting point of around 2,852°C. This characteristic, combined with resistance to electrical current, gives magnesia utility across industrial and health applications.
The Chemical Process: Forming an Ionic Bond
The formation of magnesium oxide is governed by the transfer of electrons, resulting in an ionic bond. Magnesium atoms are unstable because they possess two valence electrons. To achieve a stable configuration, the magnesium atom readily loses these two outer electrons.
The loss of two electrons transforms the neutral magnesium atom into a positively charged ion (Mg²⁺). The oxygen atom, which has six valence electrons, requires two more to complete its outer shell for stability. It readily accepts the two electrons donated by the magnesium atom, forming a negatively charged oxide ion (O²⁻).
The resulting compound is held together by electrostatic attraction between the positively charged Mg²⁺ ions and the negatively charged O²⁻ ions. This ionic bond arranges the ions into a rigid, stable structure called a crystal lattice. The Mg²⁺ and O²⁻ ions combine in a simple 1:1 ratio, resulting in the empirical formula MgO.
Real-World Applications of Magnesium Oxide
Magnesium oxide’s stability and physical properties make it a valuable compound. One primary industrial application is as a refractory material, utilized in the lining of furnaces, kilns, and crucibles. Its ability to withstand extreme temperatures is employed extensively in the steel and cement industries.
The compound is widely used in medical and health fields. It often serves as a dietary supplement to address magnesium deficiency. In pharmaceutical contexts, it functions as an effective antacid to neutralize stomach acid or, in larger doses, as a mild, short-term laxative.
Magnesia serves as an important additive in various manufacturing processes. It is used in electrical engineering as an insulating material within heating elements and cables, leveraging its high thermal conductivity and poor electrical conductivity. It is also incorporated into powdered food products as an anti-caking agent. Finally, it is used in environmental protection to neutralize acidic industrial wastewater.