Magnesium Oxide Formula Structure, Properties, Reactions

Magnesium oxide, also known as ‘Magnesia,’ is an ionic compound formed by the metal (Magnesium) and non-metal (Oxygen) by transfer of electrons between Mg2+ and O2-. The chemical formula of Magnesium oxide is MgO. It exists as a white hygroscopic solid that occurs as minerals in nature as ‘periclase,’ a mineral of magnesium that exists along with metamorphic rocks in the form of the “oxide of Magnesium.” Magnesium oxide (MgO) is abundantly present on the earth in the form of rocks such as Dolomite, silicate, and magnesite. Magnesium oxide is also present in the seawater and is produced mainly by the calcination of magnesite or magnesium carbonate (MgCO3).

In this article, let’s discuss everything about magnesium oxide chemical formulas with their properties and uses.

Chemical Formula and Structure of Magnesium Oxide

Magnesium oxide (MgO) is an ionic compound formed by the transfer of valence electrons of both Magnesium and Oxygen. Magnesium is electropositive in nature and has two valence electrons, and as Oxygen is more electronegative, it tends to attract valence electrons towards itself, whereas the Magnesium atom tends to donate its two valence electrons to form its stable electronic configuration. As a result, a strong electrostatic force of attraction holds the cation (Mg2+) and anion (O2-) together to form an ionic bond in MgO.

Study Magnesium Chloride Formula Here

The crystal lattice of magnesium oxide has an octahedral geometry; it is ‘Halite’ in shape, having a lattice constant of “a = 4.212 Å”. In which Mg2+ and O2- ions are tightly bounded, giving rise to their high melting point.

Physical Properties of Magnesium Oxide

The physical properties of magnesium oxide are explained below:

Chemical formula: MgO
Common Name: Magnesia
Molar Mass: 40.304 g/mol
Physical Appearance: White powder
Melting Point: 2852°C
Boiling Point: 3600°C
Density: 3.6 g/cm³
Crystal Structure: Halite (Cubic)

Production of Magnesium Oxide

  1. By Calcination of Magnesite

Calcination of Magnesite or magnesium carbonate (MgCO3) is the most common method used to produce magnesium oxide. A kiln with variable temperature is used for magnesite calcination, where it decomposes into magnesium oxide, and carbon dioxide gas is released.

  1. By Calcination of Magnesium Hydroxide

Calcination of magnesium hydroxide includes heating a filter cake containing 50-72% solid magnesium hydroxide solids at around 350°C.

  1. From Dolomite

Dolomite [CaMg(CO3)2] is an anhydrous carbonate mineral composed of calcium magnesium carbonate; Magnesium oxide is extracted from Dolomite powder by treating it with sulfuric acid to convert the lime to insoluble CaSO4 and the magnesia or Magnesium oxide to soluble MgSO4. The product was separated by filtration and by the same procedure, MgSO4 was converted to MgCO3 or Mg(OH)2 and then calcined to MgO.

Uses of Magnesium Oxide

Magnesium oxide, as an excellent basic oxide, can be used as an antacid to treat indigestion, heartburn, and sour stomach. Magnesium oxide is also given to patients before surgery because it serves as a laxative in the short term, allowing for faster stool emptying. Magnesium oxide is also utilized in crackers because the production of MgO causes magnesium to burn with a very bright white flame in the air. It is used to enhance the overall brilliance of the pyrotechnics by adding appealing white sparks.

Thus magnesium oxides have several uses in industries, medicines, as well as in our daily life. Some of them are given below:

  1. Refractory Materials: One of the world’s largest consumers of Magnesium oxide is Refractory industries due to their ability to withstand very high temperatures. Refractory materials are predominantly used as furnace linings for elevated temperatures. Magnesium oxide is very commonly used in making crucibles. Magnesium oxide nanoparticles are used as high-temperature dehydrating material for manufacturing silicon steel sheets, the ceramic material of good quality, electronic industry material, adhesive and additive in the chemical raw material.

  2. Medicinal Uses: Magnesium oxide gives relief to heartburn due to acidity, acts as an antacid because magnesium oxide reacts with water inside the body to form magnesium hydroxide, which is a good base that helps to neutralize the acid in the stomach. Supplements of magnesium oxide are also used as a short-term laxative to improve symptoms of indigestion. Our body needs magnesium for the normal functioning of muscles, nerves, and cells. Thus, Magnesium oxide is also used as a supplement of magnesium that helps to treat low Mg levels in the body.

  3. Environmental Remediation: Magnesium oxide has an acid buffering capacity and stabilizes dissolved heavy metals. Due to these properties, it is used extensively in soil and groundwater remediation, wastewater treatment, drinking water treatment, and air emissions treatment.

  4. Pyrotechnics: Magnesium oxide is also used in fireworks or crackers because magnesium burns with a very bright white flame in the air due to the formation of MgO, so it is used to add brilliance to the fireworks.

  5. Construction: It is used as a fireproof material in the construction of walls.

Burning of Magnesium Ribbon

Magnesium ribbon burns to form Magnesium oxide, which produces dazzling white light of high intensity. It is an exothermic process.

Let’s discuss an experiment based on the burning of Magnesium ribbon:

Magnesium reacts with steam to produce Magnesium oxide. Magnesium (in the form of Mg ribbon) slowly reacts with water (steam) to produce the metal oxide, and hydrogen gas is released.

Hazards caused due to Magnesium Oxide

Inhalation of Magnesium oxide may cause irritation to the eyes, nose as well as the respiratory tract. Metal fume fever is a flu-like fever that leads to a metallic taste to the patients, headache, chills, fever, and cough. This fever is caused due to exposure to Magnesium oxide.


In short, Magnesium oxide is a basic oxide of metal magnesium. It is an ionic compound having a chemical formula MgO that is held by strong electrostatic forces of attraction. In MgO, Magnesium is a cation having a +2 charge, and Oxygen is an anion because of the -2 charge. Due to this reason, instead of molecular geometry, the crystal lattice structure is studied. It has a similar lattice structure to NaCl.

Magnesium oxide is a white, hygroscopic powder which means, it has the capacity of withholding water molecules from the environment by absorption or adsorption. It is present in nature in abundant quantity and is extracted from minerals such as Dolomite. MgO is also produced by the calcination of Magnesite and Magnesium hydroxide. Due to ionic bonds, Magnesium oxide has a high melting point and boiling point. Because of this unique property to withstand high temperatures, it is widely used as a refractory material in industries. Magnesium oxide is also very important in medicines as it is used as an antacid and laxative. It is also used in crackers due to dazzling white light produced due to the formation of MgO on burning magnesium in the air.

FAQs on Magnesium Oxide Formula

Q.1. What is magnesium oxide?

Ans: Magnesium oxide is an ionic compound formed from Magnesium and Oxygen. It exists as a white, odorless powder. It is a metal oxide, thus basic in nature. It is used as an antacid to treat indigestion, etc.

Q.2. Why is the formula of magnesium oxide, MgO?

Ans: Magnesium oxide is an ionic compound formed by the transfer of valence electrons. As Oxygen is more electronegative, it tends to attract valence electrons towards itself whereas, the magnesium atom tends to donate its two valence electrons to form its stable electronic configuration. As a result, a strong electrostatic force of attraction holds the cation (Mg2+) and anion (O2-) together to form an ionic bond in MgO. Thus, the formula of magnesium oxide is MgO.

Q.3. What is the name for MgO2?

Ans: MgO2 is known as magnesium dioxide. It is another oxide of magnesium.

Q.4. Which is the best formula for magnesium oxide?

Ans: The best formula for magnesium oxide is MgO. As magnesium donates its two valence electrons to Oxygen, forming a stable ionic compound.

Q.5. How is magnesium oxide different from magnesium?

Ans: Magnesium oxide is a compound of magnesium and Oxygen with the symbol MgO while; Magnesium is a pure element. It is a metal having the symbol Mg and atomic number 12. When Mg burns in the air, it forms MgO.

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