How to draw MgCl2 Lewis Structure? - Science Education and Tutorials

Drawing MgCl2 Lewis Structure is very easy. Here in this post, we described step by step method to construct MgCl2 Lewis Structure.

Table of Contents

Key Points To Consider When Drawing The MgCl2 Lewis Structure

A three-step approach for drawing the MgCl2 Lewis structure can be used. The first step is to sketch the Lewis structure of the MgCl2 molecule, to add valence electron around the magnesium atom; the second step is to valence electron to the two chlorine atoms, and the final step is to combine the step1 and step2 to get the MgCl2 Lewis Structure.

The MgCl2 Lewis structure is a diagram that illustrates the number of valence electrons and bond electron pairs in the MgCl2 molecule. The geometry of the MgCl2 molecule can then be predicted using the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory), which states that molecules will choose an MgCl2 geometrical shape in which the electrons have from one another.

Finally, you must add their bond polarities to compute the strength of the Mg-Cl bond (dipole moment properties of the MgCl2 molecule). The magnesium-Chlorine bonds in magnesium chloride(MgCl2), for example, are polarised toward the more electronegative chlorine, and because both bonds have the same size and opposite to each other, their sum is zero due to the MgCl2 molecule’s bond dipole moment, and the MgCl2 molecule is classified as a nonpolar molecule.

The molecule of magnesium chloride (with linear geometry) is tilted at 180 degrees and has a difference in electronegativity values between chlorine and magnesium atoms, with magnesium’s pull being less than chlorine’s terminal in the MgCl2 molecule. As a result, it has no dipole moment. The MgCl2 molecule has no dipole moment due to an equal charge distribution of negative and positive charges.

MgCl2 Lewis Structure:

The central atom is magnesium, which is bordered on two terminals with chlorine atoms. Magnesium has two outermost valence electrons, indicating that it possesses two electrons in its outermost shell, whereas chlorine only has seven valence electrons in its outermost shell. To complete the octet of the chlorine atom, a chlorine terminal atom requires one electron. If you’re interested in learning more about the chlorine octet rule, please see in our previous post.

Two chlorine atoms establish covalent connections with the magnesium atom as a result, leaving the magnesium atom without any lone pairs. There are no lone pairs on the magnesium central atom that resist the bond pairs of the two Mg-Cl. According to VSEPR theory, no electronic repulsion leads the MgCl2 molecule to take on a linear molecular shape like NO2+ and CS2.

The MgCl2 molecule’s Mg-Cl bonds are arranged in a symmetrical order around the linear geometry, giving rise to the linear MgCl2 shape. The MgCl2 molecule has a linear molecular geometry because there is no electrical repulsion between them.

Electronegative Difference Calculation MgCl2 Molecule:

Magnesium has an electronegativity of 1.31, while chlorine has an electronegativity of 3.16 in the MgCl2 molecule. The difference in electronegativity can be estimated using the method below.

The electronegative value difference between magnesium and chlorine
Electronegativity value of magnesium = 1.31
Electronegativity value of chlorine= 3.16
Difference of electronegativity value between magnesium and chlorine= 3.16 – 1.31 =1.85
Electronegativity difference between Mg-Cl bond calculation of MgCl2 molecule

Due to the difference in electronegativity value of greater than 0.5, the Mg-Cl bond of the MgCl2 molecule becomes polar. Because of this difference in electronegativity, the MgCl2 molecule’s Mg-Cl bond becomes polar. The electronegativity of an atom is the strength with which it may attract bound electron pairs to its side. The polarity of MgCl2 is discussed in our previous post.

As a result, the Mg-Cl bond’s dipole moment is high due to the polarization of the bonds, and all Mg-Cl bonds’ dipoles are faced opposite to each other in the linear geometry. The MgCl2 molecule’s total dipole moment is predicted to be 0 D. It has a partial negative charge for chlorine atoms and a partial positive charge for the central magnesium atom.

The electron dot structure of the MgCl2 molecule is also known as the MgCl2 Lewis structure. It determines the number of outermost valence electrons as well as the electrons engaged in the MgCl2 molecule’s bond formation. The outermost valence electrons of the MgCl2 molecule must be understood while considering the Lewis structure of the molecule.

The magnesium atom is the middle element in MgCl2 molecular geometry, with two electrons in its outermost valence electron shell, whereas the chlorine atom has seven electrons in its outermost valence electron shell.

The MgCl2 molecule has a total of 16 valence electrons as a result of the foregoing reasoning. With the core central magnesium atom, the two-terminal chlorine atoms form covalent bonds, leaving the magnesium atom with no lone pairs on it.

The linear geometry and structure of the MgCl2 molecules are similar to that of the carbon disulfide (CS2) molecule because no lone pairs of central magnesium atoms create interaction with Mg-Cl bond pairs. The bond angle of the Cl-Mg-Cl bond is approximately 180 degrees. The Mg-Cl bond length is 181 pm(picometer).

To sketch the MgCl2 Lewis structure by following these instructions:

Step-1: MgCl2 Lewis Structure

To calculate the valence electron of each atom in MgCl2, look for its periodic group from the periodic table. The alkaline earth metal and halogen families, which are the second and 17th groups in the periodic table, are both made up of magnesium and chlorine atoms. In their outermost shells, magnesium and chlorine have two and seven valence electrons, respectively.

Because magnesium and chlorine are members of the periodic table’s alkaline earth metals and halogen family groups, their valence electrons are two and seven, respectively.

Calculate the total number of electrons in the MgCl2 molecule’s outermost valence shell. The first step is to determine how many electrons are in the MgCl2 Lewis structure’s outermost valence shell. An electron in an atom’s outermost shell is known as a valence electron. It is represented by dots in the MgCl2 Lewis diagram. The MgCl2 molecule’s core carbon atom can be represented as follows:

Total outermost valence shell electron of magnesium atom in MgCl2= 2
Total outermost valence shell electron of chlorine atom in MgCl2= 7
The MgCl2 molecule has one central magnesium atom and two chlorine atoms. Then the total outermost valence shell electrons can be calculated as follows
∴ Total outermost valence shell electrons available for MgCl2 Lewis structure( dot structure) = 2 +2*7= 16 valence electrons in MgCl2
calculation of total valence electron of MgCl2 molecule

Choose the atom with the least electronegative value atom and insert it in the center of the molecular geometry of MgCl2. We’ll choose the least electronegative value atom in the MgCl2 molecule to place in the center of the MgCl2 Lewis structure diagram in this phase. The electronegativity value in periodic groups grows from left to right in the periodic table and drops from top to bottom.

Step-2: MgCl2 Lewis Structure

As a result, magnesium is the second atom in the periodic table’s alkaline earth metal family group. Chlorine is the second member of the halogen family. The electronegative value of a magnesium atom is lower than that of a chlorine atom. Furthermore, magnesium has a two electrons limit since chlorine is the most electronegative element in the MgCl2 molecule.

In an MgCl2 Lewis structure diagram, the magnesium atom can be the center atom. As a result, central magnesium in the MgCl2 Lewis structure, with all two chlorines arranged in the two-terminal of linear geometry.

Step-3: MgCl2 Lewis Structure

Connect the exterior and core central atom of the MgCl2 molecule with two single bonds (Mg-Cl). In this stage, use two single bonds to connect all two chlorine atoms on the outside of the MgCl2 molecule to the central magnesium atom in the middle.

Count how many electrons from the outermost valence shell have been used in the MgCl2 structure so far. Each Mg-Cl bond carries two electrons because each magnesium atom is connected to two chlorine atoms by two Mg-Cl bonds. Bond pairings are what they’re called.

So, out of the total of 16 valence electrons available for the MgCl2 Lewis structure, we used 4 for the MgCl2 molecule’s two single (Mg-Cl) bonds. The MgCl2 molecule has no lone pair electrons in the center magnesium. We don’t need to put the extra electron in the molecular geometry of MgCl2.

Place the valence electrons in the Mg-Cl bond pairs starting with the core magnesium and two chlorine atoms in the MgCl2 molecule. In the MgCl2 Lewis structure diagram, we always begin by introducing valence electrons from the central magnesium atom. As a result, wrap around the central magnesium atom’s bond pair valence electrons first.

Magnesium requires 4 electrons in its outermost valence shell to complete the molecular stability. Magnesium already shares 4 electrons thanks to the two single bonds. Then place the valence electron in the chlorine atom, it placed around seven electrons. Totally, 12 valence electrons were placed on the two chlorine atoms of the MgCl2 molecule.

We’ve positioned four electrons around the central magnesium atom, which is represented by a dot, in the MgCl2 molecular structure above. The magnesium atom completes its molecular stability in the MgCl2 molecule because it possesses 4 electrons in its outermost valence shell.

Count how many outermost valence shell electrons have been used so far using the MgCl2 Lewis structure. Four electrons are shown as dots in the MgCl2 chemical structure, whereas two single bonds each contain two electrons. The outermost valence shell electrons of the MgCl2 molecule are 4 + 12= 16 as a result of the calculation.

So far, we’ve used 16 of the MgCl2 Lewis structure’s total eight outermost valence shell electrons.

Complete the middle magnesium atom stability and, if necessary, apply a covalent bond. The core atom in the MgCl2 Lewis structure is magnesium, which is bonded to the chlorine atoms by two single bonds (Mg-Cl). With the help of two single bonds, it already shares four electrons. As a result, chlorine follows the octet rule and has eight electrons surrounding it on the two terminals of MgCl2.

How to calculate the formal charge in MgCl2 Lewis Structure?

The formal charge on the MgCl2 molecule’s magnesium central atom often corresponds to the actual charge on that magnesium central atom. In the following computation, the formal charge will be calculated on the central magnesium atom of the MgCl2 Lewis dot structure.

To calculate the formal charge on the central magnesium atom of the MgCl2 molecule by using the following formula:
The formal charge on the magnesium atom of MgaCl2 molecule= (V. E(Mg)– L.E(Mg– 1/2(B.E))
V.E (Mg) = Valence electron in magnesium atom of MgCl2 molecule
L.E(Mg) = Lone pairs of an electron in the magnesium atom of the MgCl2 molecule.
B.E = Bond pair electron in Be atom of MgCl2 molecule
calculation of formal charge on magnesium atom in MgCl2 molecule

The magnesium core atom (two single bonds connected to chlorines) of the MgCl2 molecule has two valence electrons, zero lone pair electrons, and four bonding electrons. Put these values for the magnesium atom in the formula above.

Formal charge on magnesium atom of MgCl2 molecule = (2- 0-(4/2)) =0

In the Lewis structure of MgCl2, the formal charge on the central magnesium atom is zero.

Summary:

In this post, we discussed the method to construct the MgCl2 Lewis structure. Need to remember that, if you follow above-said method, you can construct molecular dot structure very easily.