Best overview: Is H2S Polar or Nonpolar? - Science Education and Tutorials

Sulfur compounds are very different in nature and similar to water. Hydrogen sulfide has the chemical formula H2S. All atoms belong to the non-metal family group in the periodic table and possess a high electronegativity value sulfur atom. Students used to ask “Is H2S polar or nonpolar?”, “H2S Lewis Structure”, “H2S molecular geometry”, “H2S bond angle”, and “H2S polarity”. In this blog post, we are going to discuss the polarity of H2S in a detailed manner.

H2S is commonly appearing at ordinary temperatures and pressures, it exists as a gas with a rotten egg smell. H2S contains one sulfur atom and two hydrogen atoms. Hydrogen sulfide (H2S) is corrosive to biological tissue and metals, and it can also induce a bad odor into the atmosphere. The sulfur atom stays the center of the molecule and the remaining two hydrogen atoms. “Is H2S polar or nonpolar?”, to answer this question, we need a detailed analysis of the polarity of the H2S molecule.

Because of the bend V- type form of hydrogen sulfide(H2S). Hydrogen has an atomic number one in the modern periodic table and one outermost valence shell electron. It comes under the hydrogen family group. Similarly, Sulfur has atomic numbers 16 and six outermost valence shell electrons.

H2S molecule is formed by elements of the oxygen and hydrogen family group in the periodic table. When H2S is exposed to air, it induces an unpleasant odor in the environment and produces white vapors that have a distinct odor and are toxic to breathe. Hydrogen Sulfide (H2S) can generate metal sulfide when it reacts with metal and undergoes sulfide corrosion.

Is H2S polar or nonpolar, then? H2S (Hydrogen sulfide) is polar due to its bent geometrical shape caused by the presence of a lone pair on the sulfur atom. Second, the difference in electronegativity between sulfur and hydrogen atoms causes the S-H bonds to become polar, causing the entire molecule to become polar as well, resulting in a net dipole moment of the H2S molecule is 0.97D. This is less than the water dipole moment.

Preparation of H2S

Hydrogen sulfide(H2S) is a gas with a strong intense unpleasant odor. It is created primarily through the acidification of metal sulfide. Sulfur is available to a large extent in coal. Carbonization of coal is the process to treat the coal at high temperatures in absence of air. This makes metallurgical coke. Some by-products are formed during this process. H2S also formed as the product in this process. It is converted into metal sulfide( Iron sulfide)

Iron sulfide (FeS) undergoes further reaction with acid and gives hydrogen sulfide(H2S). The chemical equation of the formation of H2S is shown below.

FeS + 2 HCl → FeCl2 + H2S
Preparation of hydrogen sulfide(H2S)

H2S Molar Mass Calculation

H2S has a molecular mass of 34.082 g/mol, which may be computed as follows.

Mol mass of H2S = 1 * 32 (atomic mass of S) + 2 * 1(atomic mass of H) = 34.082 g/mol.
H2S molar mass calculation

The chemical composition of the hydrogen sulfide molecule is 2 hydrogen atoms and 1 sulfur atom in the middle.

H2S Lewis Structure: Is H2S polar or nonpolar?

The core atom is sulfur, which is flanked by two hydrogen atoms. Sulfur contains six outermost valence electrons, which means it contains six electrons in its outermost shell, whereas hydrogen has one outermost electron. The sulfur atom is required two electrons to complete the octet of the sulfur atom. If you want to know about the octet rule, please see in our previous post.

As a result of this, both two hydrogen atoms form covalent bonds with the sulfur atom, leaving the sulfur atom with two lone pairs. The bond pairs of S-H are repelled by the two lone pairs on the sulfur atom. According to VSEPR theory, electronic repulsion causes the molecule’s shape to bend (V-shape), similar to that of the water molecule.

The lone pair forces both two S-H bonds downward, resulting in the bent V-type form of the H2S molecule. Because they generate electrical repulsion among the H2S molecule, lone pairs have deformed shapes of the H2S molecule.

Electronegative difference calculation H2S:

When it comes to the electronegativity value of the H2S molecule, hydrogen has an electronegativity of 2.2, while sulfur has an electronegativity of 2.58. The electronegativity difference between sulfur and hydrogen can be calculated by the following method.

Electronegativity value of hydrogen = 2.2
Electronegativity value of sulfur = 2.58
Difference of electronegativity value between sulfur and hydrogen = 2.58 – 2.2=0.38
Electronegativity difference calculation of H2S molecule

The S-H bond of the H2S molecule becomes nonpolar in nature due to this difference in electronegativity value. The power with which an atom can attract bound electron pairs towards its side is known as the electronegativity of the atom.

As a result of this, the dipole moment of the S-H bond is non zero, and the dipoles of both S-H bonds are not negated due to the V-shaped structure. The total dipole moment of the H2S molecule is calculated to be 0.97 D. Sulfur atoms receive a partial negative charge on it, while hydrogen atoms receive a partial positive charge on it.

H2S molecule’s electron dot structure is also known as H2S Lewis structure. It determines the number of outermost valence electrons and the electrons involved in the formation of the H2S molecule’s bonds. When discussing the Lewis structure of the H2S molecule, it is necessary to understand the outermost valence electrons of H2S.

Sulfur is the middle element of the molecule, with 6 electrons in its outermost valence electron shell, while hydrogen atom is the outermost valence electron shell, with one electron.

As a result of this above explanation, the H2S molecule contains a total of eight valence electrons. The two hydrogen atoms establish covalent connections with the sulfur atom, leaving the sulfur atom with two lone pairs on it.

The lone pairs of sulfur atoms cause repulsion with S-H bond pairs, causing the S-H bonds to face downward force and the shape of the molecules to bend like that of the H2O (water) molecule. The H-S-H bond has a bond angle of roughly 92 degrees. S-H bond has a bond length of 134 pm (picometer).

To sketch the H2S Lewis structure by following these instructions:

Step-1: Determine the total number of outermost valence shell electrons in the H2S molecule. The first step is to figure out how many outermost valence shell electrons there are in the H2S Lewis structure. A valence electron is one of an atom’s outermost shell electrons. In the Lewis diagram, it is represented by dots. The central sulfur atom of the H2S molecule can be represented as follows

Look for the periodic group of each atom in H2S to determine its valence electron. Sulfur and hydrogen are both members of the oxygen and hydrogen family, which is the 16th and 1st groups in the periodic table respectively. Hydrogen and sulfur have one and six valence electrons in their outermost shell respectively.

Because sulfur and hydrogen belong to the oxygen and hydrogen family group in the periodic table, their valence electrons are six and one respectively.

Total outermost valence shell electron of the hydrogen atom in H2S = 1
Total outermost valence shell electron of a Sulfur atom in H2S= 6
The H2S molecule has one central sulfur atom 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 + 1*2 = 8 valence electrons in H2S
calculation of total valence electron of H2S molecule

Step-2: Locate the atom with the least electronegative charge and place it in the center of the H2S molecular geometry. In this phase, we’ll select the least electronegative atom in the H2S molecule to place in the Lewis structure diagram’s center. In the periodic table, the electronegativity value increases in order from left to right and decreases in order from top to bottom in periodic groups.

As a result, Hydrogen is the second atom in the hydrogen family group in the periodic table. Sulfur comes second in the oxygen family group. A hydrogen atom has a lower electronegative value than a sulfur atom. Furthermore, hydrogen has a low number of valence outermost electrons. it can never be the central atom in an H2S Lewis structure diagram. As a result of this, place sulfur at the center of the H2S Lewis structure, with hydrogen uniformly around it the V shape structure.

Step-3: Use two single bonds (S-H) to connect the outside and core atoms in the H2S molecule. Connect all outside atoms (hydrogen) to the core central atom (sulfur) with two single bonds in this stage.

Count how many outermost valence shell electrons we’ve used so far in the H2S structure. Because each Sulfur atom is connected to a hydrogen atom by two single (S-H) bonds, each connection contains two electrons. Those are called bond pairs.

So, from the total of 8 valence electrons available for the H2S Lewis structure, we employed 4 electrons for two single (S-H) bonds in the H2S molecule. There are still 4 valence electrons left in the H2S molecule. Where do we need to place them in H2S molecular geometry?

Step-4: Starting with the outer two hydrogen atoms in the H2S molecule, place the remaining valence electrons. We always start inserting valence electrons from the exterior atom first in the Lewis structure diagram. As a result, first, wrap around the leftover valence electrons on each hydrogen atom.

Hydrogen atom requires one electron in its outermost valence shell. With the help of a single bond, each hydrogen already shares two electrons. Put zero electrons around each hydrogen atom and you’re done with the hydrogen in the H2S molecule.

In the H2S molecule structure above, we’ve put no electrons around the hydrogen atoms, represented by a dot. As all hydrogen atoms have one electron in their outermost valence shell, each hydrogen atom comfortably completes its not octet stability in the H2S molecule.

Using the Lewis structure, count how many outermost valence shell electrons have been consumed so far. In the H2S molecular structure, 4 electrons are represented as dot structure, whereas two single bonds each contain 2 electrons. As an outcome of the calculation, the outermost valence shell electrons are 0 + 4 =4.

So far, we’ve used 4 of the total 8 outermost valence shell electrons available for the H2S Lewis structure. But now the question is, “How to fix the remaining four valence electrons?”. We also have four valence electrons to spare in the H2S molecule.

Step-5: Complete central sulfur atom octet and use covalent bond if necessary. In the H2S Lewis structure, Sulfur is the central atom and it is connected with two single bonds (S-H) to the hydrogen atoms. It means it already sharing 4 electrons with the help of 2 single bonds.

So, sulfur is obeying the rule of the octet as 8 electrons around it. Place the four remaining valence electrons around the sulfur center atom as a lone pair of electrons, which is acting as an octet stabilization in this case.

What are H2S electron and molecular geometry?

H2S has a V-shaped bent molecular geometry and water like electron geometry, according to the VSEPR theory. Because the core central atom, sulfur, has two S-H bonds with the surrounding two hydrogen atoms. In the same plane, the H-S-H bond forms a 92-degree angle. Because two hydrogen atoms are in the same plane, they form a V- type bent shape.

Above that plane, there are two lone pairs. It maintains the tetrahedral-like form after connecting the upper two lone pairs to the V-shaped bent form. The lone pair is located just opposite to bond pairs in the tetrahedral geometry. The two lone pairs of the electron are just above the V-shape bent bond pair plane in the tetrahedral geometry.

Because of the two lone pairs of electrons, it gives tetrahedral electron geometry. But the H2S molecular geometry is a V-shape bent form in nature. It is the asymmetrical geometry of the H2S molecule. S-H bonds are nonpolar in nature due to less than 0.5 electronegative difference. That makes, H2S molecule is nonpolar.

How to find H2S molecular geometry

Determine the number of lone pairs on the H2S Lewis structure’s core Sulfur atom.
We need to figure out how many lone pairs there are on the central sulfur atom of the H2S Lewis structure because the lone pairs on sulfur are primarily responsible for the H2S molecule geometry distortion.

Use the formula below to find the lone pair on the H2S molecule’s center Sulfur atom.
L.P(S) = V.E(S) – N.A(S-H)/2

Lone pair on the central sulfur atom in H2S= L.P(S)
The core central Sulfur atom’s valence electron in H2S = V.E(S)
Number of S-H bonds = N.A (S-H)
calculation for sulfur atom lone pair in H2S molecule

In the case of H2S, the center atom, sulfur, has six outermost valence shell electrons and two hydrogen atoms connected to it.

As a result of this, L.P(S) = (6 – 2)/2=2

The lone pair on the center sulfur atom of the H2S electron geometry structure is equal to two. It means, the central sulfur atom contains two lone pairs.

Determine the number of H2S molecular hybridizations.
How to find the hybridization of the H2S molecule?. Now we need to figure out what H2S’s molecular hybridization number is.

The formula of H2S molecular hybridization is as follows:
No. Hyb of H2S = N.A(S-H) + L.P(S)
No. Hy of H2S= the number of hybridizations of H2S
Number of S-H bonds = N.A (S-H)
Lone pair on the central sulfur atom = L.P(S)
Calculation for hybridization number for H2S molecule

Sulfur, then, is a central atom with two hydrogen atoms linked to it and two lone pairs in the H2S molecule. Then the number of hybridization of H2S(No. Hyb of H2S) can be calculated as follows

No. Hyb of H2S = 2+2 =4

Number of hybridization for the H2S molecule is four. one S orbital, and three p orbitals combine together to form the sp3 hybridization.

3. Use VSEPR theory to determine H2S molecular geometry shape

When the VSEPR theory is utilized to calculate the shape of the H2S molecule, the AXN approach is typically used.

The AXN notation is as follows:
The center sulfur atom in the H2S molecule is denoted by the letter A.
The bound pairs (S-H) of electrons to the core atom are represented by X.
The lone pairs of electrons on the center sulfur atom are denoted by the letter N.
Notation for H2S molecular geometry

We know sulfur is the center atom with two bound (S-H) pairs of electrons and two lone pairs. because of the H2S Lewis structure. H2S has the general molecular geometry formula AX2N2.

If the molecule has an AX2N2 generic formula, the H2S molecular geometry will be V- shape bent and the electron geometry will be tetrahedral, according to the VSEPR theory.

Name of Molecule	Hydrogen Sulfide
Chemical molecular formula	H2S
Molecular geometry of H2S	Bent V-shape
Electron geometry of H2S	Tetrahedral
Hybridization	Sp³
Bond angle (H-S-H)	92º degree
Total Valence electron for H2S	8
The formal charge of H2S on sulfur	0

How to calculate the formal charge in the H2S Lewis Structure?

The formal charge on the sulfur central atom of the H2S molecule often represents the actual charge on that sulfur central atom. The formal charge will be found on the central sulfur atom of the H2S Lewis dot structure in the following calculation.

To calculate the formal charge on central sulfur atom of H2S molecule by using the following formula:
The formal charge on 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 a sulfur atom of an H2S molecule.
B.E = Bond pair electron in S atom of H2S molecule
calculation of formal charge on sulfur atom in H2S molecule

We have 6 valence electrons, 4 lone pair electrons, and four bonding electrons in the sulfur central atom (two single bonds attached to hydrogen) of the H2S molecule. Now put these value of the sulfur atom in the above formula

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

The formal charge on central sulfur atom of H2S Lewis structure is zero.

Lewis structure of some other related post in this blog. See more detail by clicking on it, H2O, BeCl2, SF4, NH3, XeF4, BF3, BrF3, BrF5, SO3,SCl2, PCl3 and CH2Cl2 molecules.

The dipole moment of H2S

The dipole moment of the H2S molecule can assist us in determining the H2S polarity’s strength. The polarity of any molecule is proportional to its dipole moment. Because the form of H2S is asymmetric. The dipole moment of H2S does not cancel each other as a result of this.

Dipole moment of H2S can be calculated as follows
D(S-H) = Q(S-H) * R(S-H)
D(S-H) = Dipole moment of S-H bond in H2S molecule
Q(S-H) = Charge distribution in S and Hatom of H2S molecule
R(S-H)= Bond length of S-H bond in H2S molecule
Dipole moment calculation of H2S molecule

Net dipole moment of H2S molecule is 0.97 D.

Why is H2S a polar molecule?

Due to the existence of two lone pairs on the Sulfur atom, the hydrogen sulfide (H2S) molecule has a twisted V- shape bent form. According to the VSEPR hypothesis, lone pairs and bond pairs repel each other, causing the S-H bonds to move the lower side of the molecular structure, resulting in a V-shaped molecule.

The dipole moment of S-H bonds does not cancel out as it does in asymmetric H2S molecules. H2S has a dipole moment of 0.97 D across the entire molecule. The formation of a nonpolar molecule is caused by the geometrical structure and the difference in electronegativity value of atoms in the H2S molecule. The electronegative value of the S-H bond is nonpolar. That makes, H2S molecule is nonpolar.

Because of the asymmetric shape of the H2S molecule, the charge is dispersed non-uniformly among the sulfur and hydrogen atoms, resulting in the formation of positive and negative poles across the H2S molecule.

Properties of H2S

The properties of H2S are listed below

Autoignition temperature of H2S is 232 degree
The boiling point of H2S is -59.55 degree.
The gas density of H2S gas is 1.5 kg/m3.

Uses of H2S

The uses of H2S are listed as follows

It’s used to make hydrogen and sulfuric acid, among other things.
It’s commonly utilized in industry to make a wide range of inorganic chemicals.
On a bigger scale, it’s utilized to make insecticides for crops.
Heavy water, such as hydrogen sulfide, is often employed in nuclear power reactors.

Conclusion

Sulfur is more electronegative than hydrogen as mentioned above. This is due to the fact that Sulfur possesses more electrons than the latter. As you may be aware, the electronegative difference of H2S is 0.38, which is regarded as minimal and possesses weak polarity. The H2S molecule is classified as a non-polar S-H bond since there isn’t enough polarity between the atoms.

This is a one-of-a-kind situation that must be taken into account. According to some research, a molecule’s electronegativity must be between 0.5 and 2 for it to be polar. But the electron geometry of H2S has an asymmetric tetrahedral V-shape bent structure. This gives, the resultant H2S dipole moment is 0.97 D.

If you have any queries and doubts about this post, please leave a comment. We will get back to you as soon as possible.

FAQ on “Is H2S polar or nonpolar?”

Why is H2O polar but H2S is not?

Because the oxygen atom in water is very electronegative and can partially polarise the hydrogen atoms, hydrogen-hydrogen bonds can form between the H2O molecules, resulting in a relatively high boiling point. Because sulphur is substantially less electronegative than oxygen, these bonds do not occur in H2S.