How to draw H2S Lewis Structure? - Science Education and Tutorials

Q: What is the H2S Lewis structure?

H2S Lewis structure is dot representation

Q: What is the formal charge on the H2S Lewis structure?

Zero charges on the H2S molecular structure

The hydrogen sulfide chemical formula is H2S. Drawing H2S Lewis Structure is very easy to by using the following method. Here in this post, we described step by step method to construct H2S Lewis Structure. The sulfur and hydrogen elements come as the member of the oxygen and hydrogen family groups from the periodic table respectively. The valence electrons in sulfur and hydrogen are six and one respectively. Hydrogen sulfide is used to make chemical reagents for organic chemical reactions for the production of sulfur-organic materials.

Table of Contents

Key Points To Consider When Drawing The H2S Electron Dot Structure

A three-step approach for drawing the H2S Lewis structure can be used. The first step is to sketch the Lewis structure of the H2S molecule, to add valence electrons around the sulfur atom; the second step is to add valence electrons to the two hydrogen atoms, and the final step is to combine the step1 and step2 to get the H2S Lewis Structure.

The H2S Lewis structure is a diagram that illustrates the number of valence electrons and bond electron pairs in the H2S molecule. The geometry of the H2S molecule can then be predicted using the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory), which states that molecules will choose the H2S geometrical shape in which the electrons have from one another.

Finally, you must add their bond polarities to compute the strength of the two S-H single bonds (dipole moment properties of the H2S molecule). The sulfur-hydrogen bonds in hydrogen sulfide(H2S), for example, are polarised toward the more electronegative sulfur in H2S molecule, and because both bonds have the same size and are located around two hydrogen terminals of the tetrahedral or bent V-shaped with two lone pairs (in total four electrons) on the sulfur atom, their sum of dipole moment is nonzero due to the H2S molecule’s bond dipole moment and less electron polarity to the hydrogen atoms. Because each two S-H bonds polarity not canceled each other in the H2S molecule due to the presence of two lone pairs of electrons. The hydrogen sulfide(H2S) molecule is classified as a polar molecule.

The molecule of hydrogen sulfide (with tetrahedral or bent V-shaped molecular geometry) is tilted, the bond angles between sulfur and hydrogen are 92 degrees. It has a difference in electronegativity values between sulfur and hydrogen atoms, with central sulfur’s pull being higher than terminal hydrogen’s in the H2S molecule. But they not canceled each other due to the asymmetrical tetrahedral with two lone pairs in the molecular geometry of the H2S molecule.

As a result, it has the nonzero dipole moment. The H2S molecule has a nonzero dipole moment due to an unequal charge distribution of negative and positive charges. But both sulfur and hydrogen atoms fall on the oxygen and hydrogen family groups in the periodic table respectively. The sulfur atom is a more electronegative value than hydrogen in the H2S molecule. The H2S molecule has the net dipole moment of 0.95D value in the ground state energy level.

H2S molecule has two S-H 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 H2S 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: H2S Lewis Structure

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

Two hydrogen atoms establish covalent connections with the central sulfur atom as a result, leaving the sulfur atom with two lone pairs. There are two lone pairs of electrons on the sulfur central atom that resists the bond pairs of the two S-H bonds. According to VSEPR theory, the single S-H bond pairs polarity lead the H2S molecule to take on the tetrahedral geometry structure.

The H2S molecule’s two S-H bonds are arranged in symmetrical polarity order around the tetrahedral molecular geometry, giving rise to the H2S molecular shape. The H2S molecule has a tetrahedral or V-shaped bent molecular geometry because there is an electrical repulsion between the lone pairs of electrons in sulfur and two single bond pairs(S-H) of the H2S molecule.

Lewis structure of H2S has dot electron representative structure. Valence electrons of atoms undergo orbitals mixing in the chemical reactions, gives new types of molecular species of H2S. 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 H2S Molecule:

Sulfur and hydrogen Electronegative difference in H2S:

The sulfur atom has an electronegativity of 2.58, while hydrogen has an electronegativity of 2.2 in the H2S molecule. The difference in electronegativity of sulfur and hydrogen can be estimated using the method below.

The electronegative value difference between sulfur and hydrogen in H2S molecule
Electronegativity value of sulfur = 2.58
Electronegativity value of hydrogen= 2.20
Difference of electronegativity value between sulfur and hydrogen in H2S molecule = 2.58 – 2.20 = 0.38
Electronegativity difference between S-H bond calculation of H2S molecule

The electronegative difference between sulfur and hydrogen is less than 0.5. This indicated the bond polarity moves near to nonpolar nature. H-S bond polarity in the H2S molecule is nonpolar.

Because of this difference in electronegativity of sulfur and hydrogen atoms, the H2S molecule’s S-H bond becomes nonpolar. The total net dipole moment of the H2S molecule is nonzero due to the noncancellation of the bond dipole moment in the tetrahedral geometry due to the presence of two 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 H2S is discussed in our previous post.

As a result, the S-H bond’s dipole moment is less due to the polarization of the bonds and two lone pairs of electrons on sulfur, and all S-H bonds’ dipoles are arranged in the asymmetrical H2S molecular geometry. The H2S molecule has a nonzero net dipole moment.

The electron dot structure of the H2S molecule is also known as the H2S Lewis structure. It determines the number of outermost valence electrons as well as the electrons engaged in the H2S molecule’s bond formation. The outermost valence electrons of the H2S molecule must be understood while constructing the Lewis structure of the molecule.

The sulfur atom is the middle element in H2S molecular geometry, with six 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 H2S has a total of 8 valence electrons as a result of the foregoing above-said reasoning. With the core central sulfur atom, the two terminals with two hydrogen atoms form covalent bonds, leaving the sulfur atom with two lone pairs in the middle of tetrahedral geometry.

Because no lone pairs on the terminal hydrogen atoms create interaction with S-H bond pairs(but it is negligible in the ground state of the H2S molecule). The bond angle of the H-S-H bond in the tetrahedral molecular geometry is approximately 92 degrees. This angle is less than the CH4 molecule bond angle. The S-H bond length is 134pm(picometer).

To sketch the H2S Lewis structure by following these instructions:

Step-1: H2S Lewis dot Structure by counting valence electrons on the sulfur atom

To calculate the valence electron of each atom in H2S, look for its periodic group from the periodic table. The oxygen and hydrogen group families, which are the 16th and 1st groups in the periodic table, are both made up of sulfur and hydrogen atoms respectively. In their outermost shells, hydrogen and sulfur have one and six valence electrons respectively.

Calculate the total number of valence electrons in the H2S molecule’s outermost valence shell. The first step is to determine how many electrons are in the H2S 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 H2S Lewis diagram. The H2S molecule’s core sulfur atom can be represented as follows:

Total outermost valence shell electron of sulfur atom in H2S= 6
Total outermost valence shell electron of hydrogen atom in H2S= 1
The H2S molecule has one central sulfur and two hydrogen atoms. Then the total outermost valence shell electrons can be calculated as follows
∴ Total outermost valence shell electrons available for H2S Lewis structure( dot structure) = 6+2*2= 8 valence electrons in H2S.
calculation of total valence electron of H2S molecule

Choose the atom with the least electronegative value atom and insert it in the center of the molecular geometry of H2S. We’ll choose the least electronegative value atom in the H2S molecule to place in the center of the H2S Lewis structure diagram in this phase.

But in this case, hydrogen is the least electronegative than sulfur. Hydrogen takes a maximum of two-electron in its orbital. This gives hydride ion(H-). So that sulfur 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 six valence electrons around the sulfur atom as given in the figure.

Step-2: Lewis Structure of H2S for counting valence electrons around the terminal hydrogen atoms

As a result, sulfur is the second atom in the periodic table’s oxygen 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 sulfur atom is higher than that of the hydrogen atom in the H2S molecule. Furthermore, hydrogen has a one-electron limit since it is the less electronegative element in the H2S molecule.

In the H2S Lewis structure diagram, the sulfur atom can be the center atom of the molecule. As a result, central sulfur in the H2S Lewis structure, with all two hydrogen atoms arranged in a tetrahedral geometry.

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

Step-3: Lewis dot Structure for H2S generated from step-1 and step-2

Connect the exterior and core central atom of the H2S molecule with two single S-H bonds. In this stage, use two hydrogen atoms on the outside of the H2S molecule to the central sulfur atom in the middle.

Count how many electrons from the outermost valence shell have been used in the H2S structure so far. Each S-H single bond carries two electrons because each sulfur atom is connected to two hydrogen atoms by two S-H single bonds. Bond pairings of S-H are what they’re called.

So, out of the total of 8 valence electrons available for the H2S Lewis structure, we used four electrons for the H2S molecule’s two S-H single bonds. The H2S molecule has two lone pairs of electrons in the central sulfur atom.

Place the valence electrons in the S-H bond pairs starting with the core sulfur, two hydrogen atoms in the H2S molecule. In the H2S Lewis structure diagram, we always begin by introducing valence electrons from the central sulfur atom(in step1). As a result, wrap around the central sulfur atom’s bond pair valence electrons first (see figure for step1).

The sulfur atom in the molecule gets only 8 electrons around its molecular structure. This central sulfur atom is octet stable. But it has two lone pairs. Sulfur compound(S8) is a yellowish solid in nature. when sulfur undergoes sublimation from the solid-state to the gaseous state. But Sulfur is a very old anti-biotic for external uses.

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.

Sulfur requires 8 electrons in its outermost valence shell to complete the molecular octet stability, 4 electrons bond pairs in two S-H single bonds, and two lone pairs in the central sulfur atom. No lone pairs of electrons on the hydrogen atoms of the H2S molecule are placed in a tetrahedral geometry. Sulfur already shares 8 electrons to the two S-H 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 two hydrogen atoms as lone pair of electrons.

We’ve positioned 8 electrons around the two-terminal hydrogen atoms(step-3), which is represented by a dot, in the H2S molecular structure above. The sulfur atom completes its molecular octet stability in the H2S molecule because it possesses 4 electrons in its (two S-H single bonds) bond pairs with two hydrogens in the outermost valence shell.

Count how many outermost valence shell electrons have been used so far using the H2S Lewis structure. Two electron bond pairs are shown as dots in the H2S chemical structure, whereas two single bonds each contain two electrons. The outermost valence shell electrons of the H2S molecule(bond pairs) are 4 as a result of the calculation. The total valence electron in a sulfur atom is 8.

So far, we’ve used 8 of the H2S Lewis structure’s total 8 outermost valence shell electrons. Two lone pairs of electrons on the sulfur atom in the tetrahedral geometry of the H2S molecule.

Complete the middle sulfur atom stability and, if necessary, apply a covalent bond. The central sulfur atom undergoes octet stability(due to two single bond pairs of electrons).

The core atom in the H2S Lewis structure is sulfur, which is bonded to the two hydrogen atoms by single bonds (two S-H). With the help of two single bonds, it already shares 8 electrons. As a result, the sulfur follows the octet rule and has 8 electrons surrounding it on the two terminals of the H2S molecule’s tetrahedral geometry.

How to calculate the formal charge on sulfur and hydrogen atoms in H2S Lewis Structure?

Calculating formal charge on the sulfur of H2S molecule:

The formal charge on the H2S molecule’s sulfur central atom often corresponds to the actual charge on that sulfur central atom. In the following computation, the formal charge will be calculated on the central sulfur atom of the H2S Lewis dot structure.

To calculate the formal charge on the central sulfur atom of the H2S molecule by using the following formula:
The formal charge on the sulfur atom of H2S molecule= (V. E(S)– L.E(S) – 1/2(B.E))
V.E (S) = Valence electron in a sulfur atom of H2S molecule
L.E(S) = Lone pairs of an electron in the sulfur atom of the H2S molecule.
B.E = Bond pair electron in S atom of H2S molecule
calculation of formal charge on sulfur atom in H2S molecule

The sulfur core atom (two single bonds connected to two hydrogen atoms ) of the H2S molecule has six valence electrons, two lone pairs of electrons(four electrons), and 4 bonding pairing valence electrons. Put these values for the sulfur atom in the formula above.

Formal charge on sulfur atom of H2S molecule = (6- 4-(4/2)) =0

In the Lewis structure of H2S, the formal charge on the central sulfur atom is zero.

Calculating formal charge on the hydrogen atom of H2S molecule:

The formal charge on the H2S 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 H2S Lewis dot structure.

To calculate the formal charge on the terminal hydrogen atom of the H2S molecule by using the following formula:
The formal charge on the hydrogen atom of H2S molecule= (V. E(H)– L.E(H) – 1/2(B.E))
V.E (H) = Valence electron in a hydrogen atom of H2S molecule
L.E(H) = Lone pairs of an electron in the hydrogen atom of the H2S molecule.
B.E = Bond pair electron in H atom of H2Smolecule
calculation of formal charge on hydrogen atom in H2S molecule

The hydrogen terminal atoms of the H2S 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 H2S molecule = (1- 0-(2/2)) =0

In the Lewis structure of H2S, the formal charge on the terminal hydrogen atom is zero.

Summary:

In this post, we discussed the method to construct the H2S Lewis structure. First, the valence electrons are placed around the sulfur atom. Second, place the valence electron on the hydrogen atoms. Finally, when we combined the first and second steps. It gives H2S Lewis structure. Need to remember that, if you follow the above-said method, you can construct molecular dot structure very easily.