Is MgCl2 Ionic or Covalent?


Magnesium Chloride is a chemical compound that is represented by the formula MgCl2. These salts are highly soluble in water and form ionic halides.

In the anhydrous state, the Magnesium Chloride comprises 25.5% of elemental magnesium by mass. Magnesium chloride in the hydrated form can be easily extracted from seawater. The Magnesium chloride in the anhydrous state is the prime predecessor of magnesium metal.

These magnesium metals are produced in huge quantities and are required by manufacturing industries.

The molecular mass of the anhydrous Magnesium Chloride is 95.211g/mol. Magnesium Chloride appears to be a colorless crystalline solid with a melting point of 714 degrees C.

While dealing with the topic of Magnesium Chloride (MgCl2) a general question that arises is “Is MgCl2 Ionic or Covalent?”

So, is MgCl2 ionic or covalent? MgCl2 is an ionic compound because chemical bonds in the molecule are formed by the transfer of electrons among Mg and Cl atoms. Magnesium is an alkaline earth metal that loses two electrons to form magnesium cation while chlorine being a non-metal accepts the one-electron each to form a chloride ion. The electrostatic force of attraction takes place in between the oppositely charged cations and anions, which leads to the formation of the ionic compound.

Let us study its reasons in more detail.


Lewis Structure Of Magnesium Chloride (MgCl2)

To understand the chemical bonding between Magnesium and Chlorine forming the ionic bond of the MgCl2 compound, it is very important to know about its Lewis Structure.

Lewis structure is also very commonly known as the electron dot structure. In the Lewis Structure, the diagram shows the kind of chemical bonding that takes place between the atoms of a molecule.

The Lewis structure can also show the bond that may exist in between the lone pair of electrons that exists in the molecule.

The simplified diagrammatic structure represents the valence shell electrons present in the molecules. It represents the arrangements of the electrons around each atom in a molecule.

MgCl2 atoms

The electrons are represented by the dots while the bonding is shown by lines between the two or more atoms. It helps in obtaining the “best” electronic configuration that is the octet rule.

Now, we are going to discuss the Lewis Structure of Magnesium Chloride (MgCl2).

Magnesium has an atomic number 12 and belongs to group 2 of the Periodic table. While on the other hand, chlorine has an atomic number of 17 and also belongs to group 17 of the Periodic Table.

Magnesium (Mg) comprises 2 valence electrons, while Chlorine comprises 7 valence electrons. Therefore, the total number of valence electrons we get from the molecule of MgCl2 is as below.

Mg= 2 * 1

Cl= 7 * 2

The total number of valence electrons = (2*1) + (7*2) = 16.

The important criteria for the formation of an ionic compound are the presence of metal and non-metal such that one can lose electrons and form a cation while the other can accept electrons and form an anion.

Therefore, magnesium being a marvelous alkaline earth metal while Chlorine being a halogen non-metal forms the ionic compound.

There is the transfer of electrons taking place in between the atoms to attain the stabilize state, which is also known as the Octet Rule.

In the Lewis Structure of Magnesium Chloride, The Magnesium atom is placed in the middle while two Chlorine atoms are placed on either side of the Magnesium atom.

Now, we put the valence electrons with the help of dots accordingly in each atom.

The two chlorine atoms have seven valence electrons. Both of them are short of one single electron. While the magnesium atom has two additional valence electrons in its outermost shell.

The electronic configuration of the Magnesium atom (Mg) is: 1s22s22p63s2

The electronic configuration of each of the Chlorine atom (Cl) is: 1s22s22p63s23p5

Magnesium atom donates one valence electron to each of the chlorine atoms that accept the electrons to form an octet.

Now, we get the electronic configuration as follows:

The electronic configuration of the Magnesium atom (Mg) is: 1s22s22p6

The electronic configuration of each of the Chlorine atom (Cl) is: 1s22s22p63s23p6

Magnesium becomes a cation by losing two electrons and therefore, Magnesium is represented by a +2 positive charge (Mg+2) and each Chlorine on accepting one valence electron is donated by a -1 negative charge (Cl-).

This is the most stable form of Lewis Structure for Magnesium Chloride (MgCl2).

MgCl2 lewis structure


What is an Ionic Bond?

The ionic bond is typically also known as an Electrovalent bond.

The Ionic bond is a kind of linkage that is formed owing to the electrostatic force of attraction that takes place between two oppositely charged ions in a compound.

An Ionic bond is formed when the electrons present in the valence shell are transferred from one atom to the other atom.

As a result of which there will always be an atom that will lose or donate electrons to form positively charged cations, while another atom will accept and gain electrons to form negatively charged anions.

The compounds that are formed owing to the ionic bonding between two or more atoms are known as Ionic or Electrovalent Compounds, for example, Sodium Chloride, Magnesium Chloride, etc.

The best examples for the formation of an ionic compound are molecules formed by halogen nonmetals and alkaline earth metals.

In crystalline ionic solids, the electrostatic force of attraction between the oppositely charged ions and the repulsion taking place in between the similar charges makes the ions position themselves in a typical manner where each of the positive ions is surrounded by negative ions and vice versa.

MgCl2 structure

The ions align themselves in an arrangement where the positive and negative charges are placed alternatively thus balancing one another.

Therefore, the resultant charge of the entire substance or compound is zero.


What is a Covalent Bond?

The interatomic linkages that take place because of the sharing of an electron pair between two or more atoms are known as Covalent Bond.

The irrevocable binding takes place because it comprises simultaneous electrostatic forces of attraction of two nuclei for one or more pairs of electrons.

The electrons that are placed between the two nuclei are known as the bonding electrons. Generally, the covalent bonds take place in between identical atoms.

A covalent bond can also take place in between different atoms where there is a very slight difference in electronegativity between the atoms.

As a result of which these atoms, owing to the slight difference in electronegativity are insufficient in allowing the transfer of electrons from one atom to the other.

One of the examples of a covalent compound is water ie; H2O. 

Check out the article written on the covalent nature of CO2.

CO2 lewis structure


Why is Magnesium Chloride an Ionic Compound?

From the above discussion, we have found, what defines an Ionic compound.

Compounds that have been formed because of the Ionic bonding between themselves are known as Ionic compounds.

The transfer of electrons taking place across the valence shell of two or more atoms where one atom donates electrons while the other atom accepts the donated electron forms the ionic compound.

Ionic compounds are formed when atoms gain or lose valence electrons. The transfer of electrons between the atoms results in the formation of an Ionic or Electrovalent Compound.

As we know that Magnesium being an alkaline earth metal has the atomic number 12. It comprises two electrons in its valence shells.

While Chlorine being a halogen non-metal has the atomic number 17, and comprises seven electrons in its valence shell.

A chlorine atom requires only one single electron to achieve its most stable state which is the octet state.

There is the presence of two chlorine atoms and one Magnesium atom in the MgCl2 molecule.

Magnesium has to lose two electrons, to attain stability. Now by placing the Magnesium atom at the center, with two Chlorine atoms on either side of the Magnesium atom, the Magnesium atom will be able to donate one electron to each of the Chlorine atoms.

As a result, Magnesium now becomes (+2) cation, while the Chlorine atom becomes (-1) anion. The electrostatic force of attraction between the two oppositely charged ions results in the formation of the ionic compound of MgCl2.

MgCl2 electron transfer


MgCl2 Polarity

Polarity is an important feature while discussing the chemical bonding of a compound. The Pauling electronegativity chart will help us understand the bond of MgCl2.

The electronegativity value of Mg is 1.31 whereas for Cl the value is 3.16. The difference between the electronegativity value is = 3.16 – 1.13 = 1.85.

The increase in electronegativity between the atoms increases the ionic character of the chemical compound.

A compound is said to be ionic if the electronegativity is more than 1.7.

Therefore, Mg-Cl is an ionic bond and its molecule is also polar-ionic.




After having an elaborative discussion, we can conclude by saying:

1. The ionic compound takes place by the complete transfer of valence electrons from one atom to another atom. Generally, one atom is an alkaline metal while the other atom is a nonmetal.

2. Magnesium Chloride is an Ionic Compound because Magnesium having two valence electrons donates one to each of the Chlorine atoms. While each of the two Chlorine atoms requires only one electron to be in the Octet state.

And therefore, each Chlorine atom accepts one electron from the Magnesium atom.

3 By the transfer of valence electrons, Magnesium becomes positively charged (+2) and Chlorine becomes negatively charged (-1).

4. The resultant electronic configuration of the Magnesium atom (Mg) is 1s22s22p6.

5. The resultant electronic configuration of each of the Chlorine atoms (Cl) is 1s22s22p63s23p6.

6. An increase in the value of electronegativity increases the ionic nature of a chemical compound.

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