Magnesium Chloride Formula

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How to Write the Chemical Formula of Magnesium Chloride?

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Magnesium Chloride is an ionic compound. The molecular formula of magnesium chloride is MgCl2. It is generally used in industrial, food, and medical industries. It is mainly used for dust control and road stabilization and de-icing of highways, sidewalks in snowy places. Apart from the production of magnesium metal, magnesium chloride is also used for a variety of other applications, fertilizers, and mineral supplements for animals, wastewater treatment, fireproofing agents, types of cement, and refrigeration brine. 

What are Ionic Compounds?

An Ionic compound is a chemical compound that is composed of both metals and non-metals. The bond is formed on the basis of electrostatic forces between negatively (anion) and positively (cation) charged ions. Ionic bonding occurs when one or more electrons from one atom get transferred to another. The Magnesium Chloride formula is derived when Magnesium and Chloride ions combine to form the ionic compound MgCl2 (Magnesium Chloride).

What is a Structural Formula?

The formula that shows how the atoms in a molecule are bonded together and by what kinds of bonds is called a structural formula. It indicates the arrangement of atoms within a molecule by connecting atoms with a line or lines to represent a chemical bond. 

Example: H – Cl, H-O-H, O=C=O, H-N-H



The structural formula gives the bonding sequence of atoms in the molecule. 

Example: The 3 atoms in CO2 (Carbon dioxide) is bonded O=C=O, not O=O=C.

The Symbols in the Magnesium Chloride Formula

Magnesium (solid) = Mg

Chlorine (gas) = Cl

Deriving the Magnesium and Chlorine Formula

Let us look into the steps to write the chemical formula of Magnesium Chloride.

  1. Write the symbols for each element. 

  2. Look at the molecular formula of magnesium chloride and charge for each element using the Periodic table. Write it above each element.

Valency of Mg = 2+

Valency of Cl = 1-

Mg2+ Cl-1

  1. See, if the charges are balanced. 

  2. Add subscripts to the elements if necessary so the charge for the entire compound becomes zero.

  3. Use the crisscross method to check whether it is done correctly. 

Mg2+ Cl-1

 Mg1 Cl2

  • Therefore, MgClis the chemical formula of Magnesium Chloride.

Note: We really do not have to write the subscript 1. Then we can remove the charges. To verify whether the method is correct, we need to go through the following steps:

  1. Remember Mg had two positive charges and chlorine has one negative charge. 

  2. After doing the crisscross method, we have two chlorine atoms, which is two times the one minus to get a negative two there, and in magnesium, one time the two-plus to get positive two. Therefore, plus two minus two add up to zero. Hence the net charge is 0. Thus, we conclude that the derivation of the formula for Magnesium Chloride is correct.

Therefore, the Magnesium Chloride equation can be written as 

Mg (S) + Cl2 (g) -🡪 MgCl2 (S)

The method of crisscross is the foundation of Chemistry. This method can be used in deriving formulas for any other compound. Understanding the periodic table and learning the valency of each element is important. 

FAQ (Frequently Asked Questions)

1. Define an Ionic Compound. State Any Two Physical Properties of an Ionic Compound. Give an Example of an Ionic Compound with its Chemical Formula. 

Ans. An Ionic compound is a chemical compound that is composed of both metals and non-metals. Two physical properties of an ionic compound are:

i. They are hard and brittle.

ii. They have high boiling and melting points. 

Magnesium chloride is an ionic compound since it comprises one metallic atom (Mg) or cation and two non-metallic atoms (Cl) or anions.  The chemical formula for Magnesium Chloride is Mg (S) + Cl₂ (g) -🡪 MgCl₂ (S).

2. Write the Formula of Magnesium Chloride and Sodium Sulfate.

Both magnesium chloride and sodium sulfate are ionic compounds. While the chemical formula of magnesium chloride is MgCl₂, the chemical formula of sodium sulfate or sodium sulphate is Na₂SO₄. 

In the chemical formula of sodium sulfate, Na is sodium (2 atoms) and SO₄ is the sulfate component wherein S is sulphur (1 atom) and O is oxygen (4 atoms). 

3. What Do You Understand by the Structural Formula of a Compound?

Ans. The structural formula of a compound is the arrangement of atoms within a molecule. It is represented by connecting the atoms with a straight line or lines that are symbolic of the chemical bond(s) between them.