Lewis Structure, Molecular Geometry, Hybridization, and Polarity of Magnesium Chloride

MgCl2 is an ionic halide salt that contains the elements magnesium and chlorine. It is a white or colourless crystalline solid substance that is inorganic in origin. It has a molar mass of 95.211 g/mol and contains roughly 25.5 percent Mg by mass in its anhydrous state.

It has a density of 2.32 g/cc and a boiling point of 1685 K.

From brine, we can extract hydrated MgCl2. In addition, different degrees of bitterness can be found in MgCl2 solutions, which is dependent on the amount of Mg present.

Magnesium chloride is used in a variety of ways.

It’s utilised for ice control in low-temperature road and pavement de-icing. MgCl2 is used to manage dust and to prevent wind erosion.

Aside from that, we observe anhydrous magnesium chloride being employed as a precursor to metallic magnesium.

MgCl2    —–>    Mg   +   Cl2

Chemical Adhesion

We have a large array of elements in this cosmos that combine to form a wide range of chemical combinations.

Atoms are attracted to one another and create a variety of molecules with different chemical compositions.

Chemical bonding is the study of atomic attraction that leads to the production of products.

Chemical bonding is a fascinating and well-known idea in chemistry, and there are various different types of bonds to analyse and comprehend. This approach can also help us understand the chemical and physical features of a substance.

In this article, we’ll look at the nature of chemical bonding within a MgCl2 molecule.

Structure of Lewis

A Quick Overview

The Lewis Structure is the first and most important step in grasping the concept of bonding.

To locate the most appropriate Lewis We must draw skeleton electron-dot diagrams of the constituent elements along with their valence electrons to determine the structure of a specific molecule or ionic composition (electrons present in the outermost shell).

As a result, we have a 2D graphical depiction of a molecule in which we can see the different types of bonds that exist between atomic atoms.

Let’s make a Lewis Structure diagram for MgCl2 now.

MgCl2 Lewis Structure

The Periodic Table is depicted in this diagram. As can be seen, Mg is a member of group 2 with an atomic number of 12, whereas Cl is a member of group 17 with an atomic number of 17.

The valence electrons of Mg are two, while the valence electrons of Cl are seven.

In a molecule of magnesium chloride, the total number of valence electrons is 21 + 72 = 16.

Magnesium is an alkaline earth metal, as we all know. Chlorine, on the other hand, is a non-metal because it is a halogen.

Because this combination produces an ionic molecule, the bond type is ionic rather than covalent.

In covalent bonds, electron pairs are shared, whereas in ionic bonds, electrons are transferred.

However, in both circumstances, we strive to complete the octet, or the octet rule.

The Octet Rule states that the principal group elements in groups 1-17 have the noble gas elements’ valence shell octet arrangement.

Let’s do a rough sketch now:

The sketch looks like this if the valence electrons are placed correctly:

The octet configuration is only one electron away for both Chlorine atoms, but Mg has only two valence electrons.

Mg has the following electronic configuration:

1s2 2s2 2p6 3s2 Mg

Cl’s electrical configuration is as follows:

Cl: 1s2 2s2 2p6 3s2 3p5

Each of Magnesium’s valence electrons will be transferred to both Cl atoms.

Mg’s electron configuration will now be:

1s2 2s2 2p6 Mg

Alternatively, Mg: [Ne]

As a result, each Cl atom’s electron configuration is:

Cl:1s2 2s2 2p6 3s2 3p6  or  Cl: [ Ar ]

Mg loses two electrons and becomes cationic with a +2 positive charge, while Cl gains one electron and becomes Cl-.

The most appropriate Lewis Structure diagrammatic representation of MgCl2 is this.

We put the negative and positive charges in brackets to describe the ionic nature.

Polarity of MgCl2

We’ll talk about polarity, which is an important physical feature of chemical compounds.

It is concerned with the separation of electric charges between atoms inside a molecule structure, which causes dipole moments as a result of differences in electronegativity values.

If the electronegativity values of constituent atoms differ, it signifies that electrons will be shared unequally. This causes partial positive and negative charges to develop on the electropositive and electronegative components, resulting in the creation of a polar bond.

As a result, polarity is intimately linked to the second term, electronegativity.

MgCl2’s polarity

We have a representation of the Pauling Electronegativity Chart, which allows us to quickly determine the values of each element.

Mg has an electronegativity value of 1.31 in each Mg-Cl bond found inside a molecule of MgCl2, while Cl has a value of 3.16.

3.16 – 1.13 = 1.85 is the difference in electronegativity values.

The ionic character of a bond increases as the difference in electronegativity between atoms grows, and a difference of greater than 1.7-2 is usually termed ionic.

As a result, Mg-Cl has an ionic bond, and the molecule is polar-ionic. As a result, we now have a polar molecule.

Because “like dissolves like,” MgCl2 dissolves in water, a polar solvent that carries partial charges on hydrogen and oxygen. Hydrogen has a positive charge, whereas oxygen has a negative charge. MgCl2 dissolves in water because the positively charged Mg coordinates with oxygen and the negatively charged Cl coordinates with hydrogen.

One such ionic substance is KCl. I’ve also published an article on it. It’s available at KCl Lewis Structure, Geometry, and Hybridization.

Geometry of Molecular Structure

The 3-dimensional structure of molecules that we deduce from Lewis Structure using VSEPR (Valence Shell Electron Pair Repulsion Theory) is referred to as molecular geometry for covalent compounds.

Because this theory is based on the concept of electron sharing, it is inapplicable to ionic compounds, which establish bonds by the transfer of electrons, resulting in positive and negative charges.

VSEPR is only relevant to ionic substances like nitrates and carbonates that have a polyatomic ion configuration.

However, we can’t utilise this model because we don’t have a molecular geometry for MgCl2.

For their crystalline organisation, magnesium chloride forms lattice structures. The geometric pattern arrangement of atoms around the central atom is referred to as coordination geometry. It is a 6-coordinate octahedral for MgCl2.

Cadmium chloride has a crystal structure similar to this one (CdCl2).

Hybridization of MgCl2

Orbital hybridization is a term used to explain the chemical bonding that occurs within various molecule compositions.

The combining of various atomic orbitals of the same atom with equivalent energies to generate hybridised orbitals that participate in bonding is discussed in this concept.

Hybridization is an important concept for explaining the nature of covalent bonds.

In ionic compounds such as MgCl2, however, molecules are created by the complete transfer of electrons from the electropositive atom to the electronegative atom, resulting in ions.

Electrostatic attraction is at work here, and the ionic bonds that form are non-directional. In this scenario, we don’t need to deal with orbital energy, thus hybridization isn’t necessary.


Magnesium Chloride is an ionic halide that has been discussed in this article (MgCl2). The steps to draw the Lewis Structure have been added to discuss the nature and type of bond creation. Apart from that, we’ve discussed MgCl2’s polarity and coordination geometry.

Good luck with your studies!

Read more: Is NH2- a polar or nonpolar substance?

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


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