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

Q: What is the HCl Lewis structure?

HCl Lewis structure is dot representation

Q: What is the formal charge on the HCl Lewis structure?

Zero charges on the HCl molecular structure

The hydrogen chloride or hydrochloric acid chemical formula is HCl. Drawing HCl Lewis Structure is very easy to by using the following method. Here in this post, we described step by step method to construct HCl Lewis Structure. The chlorine and hydrogen elements come as the member of the halogen and hydrogen family groups from the periodic table respectively. The valence electrons in chlorine and hydrogen are seven and one respectively. Hydrogen chloride is used to make chemical reagents for organic chemical reactions as a catalyst or reagent in organic chemistry.

Table of Contents

Key Points To Consider When Drawing The HCl Electron Dot Structure

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

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

Finally, you must add their bond polarities to compute the strength of the one H-Cl single bonds (dipole moment properties of the HCl molecule). The hydrogen-chlorine bonds in hydrogen chloride(HCl), for example, are polarised toward the more electronegative chlorine in HCl molecule, and because both bonds have the same size and are located around one hydrogen terminal of the tetrahedral or linear structure with three lone pairs (in total six electrons) on the chlorine atom, their sum of dipole moment is nonzero due to the HCl molecule’s bond dipole moment and less electron polarity to the hydrogen atoms. Because H-Cl bonds polarity is not canceled in the HCl molecule due to the presence of three lone pairs of electrons in the tetrahedral structure. The hydrogen chloride(HCl) molecule is classified as a polar molecule.

The molecule of hydrogen chloride(with tetrahedral or linear-shaped molecular geometry) is tilted, the bond angles between chlorine and hydrogen are 180 degrees. It has a difference in electronegativity values between chlorine and hydrogen atoms, with central chlorine’s pull being higher than terminal hydrogen’s in the HCl molecule. But they not canceled each other due to the asymmetrical tetrahedral with three lone pairs in the molecular geometry of the HCl molecule.

As a result, it has the nonzero dipole moment. The HCl molecule has a nonzero dipole moment due to an unequal charge distribution of negative and positive charges. But both chlorine and hydrogen atoms fall on the halogen and hydrogen family groups in the periodic table respectively. The chlorine atom is a more electronegative value than hydrogen in the HCl molecule. The HCl molecule has the net dipole moment of 1.08D value in the ground state energy level.

HCl molecule has two H-Cl single bonds. Its dipole moment in the ground state is totally different as compared with the excited state. If it absorbs light may be from visible or UV light. It undergoes pi to pi star and n to pi star transition from ground state energy level to excited state energy level. In the excited state energy level, the HCl molecule shows a definite dipole moment. But it is very dynamic in nature.

Molecules can be classified as polar or nonpolar. The molecule polar behaves in a different manner as compared to nonpolar.

Overview: HCl Lewis Structure

The central atom is chlorine, which is bordered on two terminals with hydrogen atoms( in tetrahedral or linear geometry), and three lone pairs on the central chlorine atom in the tetrahedral or linear molecular geometry. Chlorine has seven outermost valence electrons, indicating that it possesses seven electrons in its outermost shell, whereas hydrogen also has one valence electron in its outermost shell. To complete the octet of the chlorine atom requires one valence electron on each of their outermost shell.

One hydrogen atom establishes covalent connections with the central chlorine atom as a result, leaving the chlorine atom with three lone pairs. There are three lone pairs of electrons on the chlorine central atom that resists the bond pairs of the H-Cl bond. According to VSEPR theory, the H-Cl bond pairs polarity lead the HCl molecule to take on the linear or tetrahedral geometry structure.

The HCl molecule’s two H-Cl bonds are arranged in asymmetrical polarity order around the linear or tetrahedral molecular geometry, giving rise to the HCl molecular shape. The HCl molecule has a tetrahedral or linear molecular geometry because there is an electrical repulsion between the lone pairs of electrons in chlorine and one single bond pair(H-Cl) of the HCl molecule.

Lewis structure of HCl has dot electron representative structure. Valence electrons of atoms undergo orbitals mixing in the chemical reactions, gives new types of molecular species of HCl. The molecule is nothing but a bundle of valence electrons from the atoms. But it is converted to bond pairs and lone pairs in the molecular structure.

Electronegative value Difference Calculation of HCl Molecule:

Chlorine and hydrogen Electronegative difference in HCl:

The chlorine atom has an electronegativity of 3.16, while hydrogen has an electronegativity of 2.2 in the HCl molecule. The difference in electronegativity of chlorine and hydrogen can be estimated using the method below.

The electronegative value difference between chlorine and hydrogen in HCl molecule
Electronegativity value of chlorine= 3.16
Electronegativity value of hydrogen= 2.20
Difference of electronegativity value between chlorine and hydrogen in HCl molecule = 3.16 – 2.20 = 0.96
Electronegativity difference between H-Cl bond calculation of HCl molecule

The electronegative difference between chlorine and hydrogen is greater than 0.5. This indicated the bond polarity moves polar nature. H-Cl bond polarity in the HCl molecule is polar.

Because of this difference in electronegativity of chlorine and hydrogen atoms, the HCl molecule’s H-Cl bond becomes polar in nature. The total net dipole moment of the HCl molecule is nonzero due to the noncancellation of the bond dipole moment in the linear or tetrahedral geometry due to the presence of three lone pairs of electrons. The electronegativity of an atom is the strength with which it may attract bound electron pairs to its side. The polarity of HCl is discussed in our previous post.

As a result, the H-Cl bond’s dipole moment is higher due to the polarization of the bonds and three lone pairs of electrons on chlorine, and all H-Cl bonds’ dipoles are arranged in the asymmetrical HCl molecular geometry. The HCl molecule has a nonzero net dipole moment.

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

The chlorine atom is the middle element in HCl molecular geometry, with seven electrons in its outermost valence electron shell, whereas the hydrogen atom has one electron in its outermost valence electron shell. The hydrogen atom has one valence electron.

The HCl has a total of 8 valence electrons as a result of the foregoing above-said reasoning. With the core central chlorine atom, the one terminals with one hydrogen atom form covalent bonds, leaving the chlorine atom with three lone pairs in the middle of linear or tetrahedral geometry.

Because three lone pairs on the terminal chlorine atoms create interaction with H-Cl bond pairs(but it is negligible in the ground state of the HCl molecule). The bond angle of the H-Cl bond in the linear or tetrahedral molecular geometry is approximately 180 degrees. This angle is greater than the CH4 molecule bond angle. The H-Cl bond length is 127pm(picometer).

To sketch the HCl Lewis structure by following these instructions:

Step-1: HCl Lewis dot Structure by counting valence electrons on the chlorine atom

To calculate the valence electron of each atom in HCl, look for its periodic group from the periodic table. The halogen and hydrogen group families, which are the 17th and 1st groups in the periodic table, are both made up of chlorine and hydrogen atoms respectively. In their outermost shells, hydrogen and chlorine have one and seven valence electrons respectively.

Calculate the total number of valence electrons in the HCl molecule’s outermost valence shell. The first step is to determine how many electrons are in the HCl 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 HCl Lewis diagram. The HCl molecule’s core chlorine atom can be represented as follows:

Total outermost valence shell electron of chlorine atom in HCl= 7
Total outermost valence shell electron of hydrogen atom in HCl= 1
The HCl molecule has one central chlorine and one hydrogen atoms. Then the total outermost valence shell electrons can be calculated as follows
∴ Total outermost valence shell electrons available for HCl Lewis structure( dot structure) = 7+1*1= 8 valence electrons in HCl.
calculation of total valence electron of HCl molecule

Choose the atom with the least electronegative value atom and insert it in the center of the molecular geometry of HCl. We’ll choose the least electronegative value atom in the HCl molecule to place in the center of the HCl Lewis structure diagram in this phase.

But in this case, hydrogen is the least electronegative than chlorine. Hydrogen takes a maximum of two-electron in its orbital. This gives hydride ion(H-). So that chlorine stays in the central molecular structure. The electronegativity value in periodic groups grows from left to right in the periodic table and drops from top to bottom.

The first step is to put seven valence electrons around the chlorine atom as given in the figure.

Step-2: Lewis Structure of HCl for counting valence electrons around the terminal hydrogen atom

As a result, chlorine is the first atom in the periodic table’s halogen family group. Hydrogen is the first member of the hydrogen family. It is the first element in the periodic table. The electronegative value of the chlorine atom is higher than that of the hydrogen atom in the HCl molecule. Furthermore, hydrogen has a one-electron limit since it is the less electronegative element in the HCl molecule.

In the HCl Lewis structure diagram, the chlorine atom can be the center atom of the molecule. As a result, central chlorine in the HCl Lewis structure, with one hydrogen atom arranged in a linear or tetrahedral geometry.

Add valence electron around the hydrogen atom, as given in the figure.

Step-3: Lewis dot Structure for HCl generated from step-1 and step-2

Connect the exterior and core central atom of the HCl molecule with one single H-Cl bond. In this stage, use one hydrogen atom on the outside of the HCl molecule to the central chlorine atom in the middle.

Count how many electrons from the outermost valence shell have been used in the HCl structure so far. H-Cl single bond carries two electrons because the chlorine atom is connected to one hydrogen atom by H-Cl single bonds. Bond pairings of H-Cl are what they’re called.

So, out of the total of 8 valence electrons available for the HCl Lewis structure, we used four electrons for the HCl molecule’s one H-Cl single bond. The HCl molecule has three lone pairs of electrons in the central chlorine atom.

Place the valence electrons in the H-Cl bond pair starting with the core chlorine, one hydrogen atom in the HCl molecule. In the HCl Lewis structure diagram, we always begin by introducing valence electrons from the central chlorine atom(in step1). As a result, wrap around the central chlorine atom’s bond pair valence electrons first (see figure for step1).

The chlorine atom in the molecule gets only 8 electrons around its molecular structure. This central chlorine atom is octet stable. But it has three lone pairs. Chlorine gas(Cl2) is a gas. Chlorine is very corrosive in nature. It is one of the very reactive chemical reagents for many chemical reactions.

Hydrogen molecule(H2) is in the gaseous state at normal temperature and pressure. It is used as a hydrogenating agent in the field of organic chemistry. It is highly flammable in nature. It is applied in fuel cells. During the combustion, hydrogen gas gives the stream as the final product. This reduces environmental pollution.

Chlorine requires 8 electrons in its outermost valence shell to complete the molecular octet stability, two electrons bond pairs in one H-Cl single bond, and three lone pairs in the central chlorine atom. No lone pairs of electrons on the hydrogen atoms of the HCl molecule are placed in a linear or tetrahedral geometry. Chlorine already shares 8 electrons to the one H-Cl single bonds. Then place the valence electron in the hydrogen atoms, it placed around one electron on each atom(step-2). There are no valence electrons placed around one hydrogen atom as lone pair of electrons.

We’ve positioned 8 electrons around the one-terminal hydrogen atoms(step-3), which is represented by a dot, in the HCl molecular structure above. The chlorine atom completes its molecular octet stability in the HCl molecule because it possesses 2 electrons in its (one H-Cl single bonds) bond pairs with one hydrogen in the outermost valence shell.

Count how many outermost valence shell electrons have been used so far using the HCl Lewis structure. One electron bond pairs are shown as dots in the HCl chemical structure, whereas one single bond contains two electrons. The outermost valence shell electrons of the HCl molecule(bond pairs) are 2 as a result of the calculation. The total valence electron in a chlorine atom is 8.

So far, we’ve used 8 of the HCl Lewis structure’s total 8 outermost valence shell electrons. Three lone pairs of electrons on the chlorine atom in the linear or tetrahedral geometry of the HCl molecule.

Complete the middle HCl atom stability and, if necessary, apply a covalent bond. The central chlorine atom undergoes octet stability(due to one single bond pair of electrons).

The core atom in the HCl Lewis structure is chlorine, which is bonded to the one hydrogen atom by single bonds (one H-Cl). With the help of one single bond, it already shares 8 electrons. As a result, the chlorine follows the octet rule and has 8 electrons surrounding it on the one terminal of the HCl molecule’s linear or tetrahedral geometry.

How to calculate the formal charge on chlorine and hydrogen atoms in HCl Lewis Structure?

Calculating formal charge on the chlorine of HCl molecule:

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

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

The chlorine core atom (one single bond connected to one hydrogen atom) of the HCl molecule has seven valence electrons, three lone pairs of electrons(six electrons), and 2 bonding pairing valence electrons. Put these values for the chlorine atom in the formula above.

Formal charge on chlorine atom of HCl molecule = (7- 6-(2/2)) =0

In the Lewis structure of HCl, the formal charge on the central chlorine atom is zero.

Calculating formal charge on the hydrogen atom of HCl molecule:

The formal charge on the HCl molecule’s hydrogen terminal atoms often corresponds to the actual charge on that hydrogen terminal atoms. In the following computation, the formal charge will be calculated on the terminal hydrogen atom of the HCl Lewis dot structure.

To calculate the formal charge on the terminal hydrogen atom of the HCl molecule by using the following formula:
The formal charge on the hydrogen atom of HCl molecule= (V. E(H)– L.E(H) – 1/2(B.E))
V.E (H) = Valence electron in a hydrogen atom of HCl molecule
L.E(H) = Lone pairs of an electron in the hydrogen atom of the HCl molecule.
B.E = Bond pair electron in H atom of HCl molecule
calculation of formal charge on hydrogen atom in HCl molecule

The hydrogen terminal atoms of the HCl molecule have one valence electron, no lone pairs of electrons(zero electrons), and two bonding pairing valence electrons(single bond). Put these values for the hydrogen atom in the formula above.

Formal charge on hydrogen atom of HCl molecule = (1- 0-(2/2)) =0

In the Lewis structure of HCl, the formal charge on the terminal hydrogen atom is zero.

Summary:

In this post, we discussed the method to construct the HCl Lewis structure. First, the valence electrons are placed around the chlorine atom. Second, place the valence electron on the hydrogen atom. Finally, when we combined the first and second steps. It gives HCl Lewis structure. Need to remember that, if you follow the above-said method, you can construct molecular dot structure very easily.