Is Hydrogen sulfide (H2S) ionic or covalent?
Hydrogen sulfide is a colorless gas with a molar mass of 34.08 g·mol−1. It is poisonous and flammable with a smell like rotten gas. It is also dangerous for the environment. It is produced by anaerobic digestion in which microorganisms break down the organic matter in the absence of oxygen.
In this article, we will discuss Is H2S ionic or covalent? bond types in H2S and all explanations regarding the nature of bonds present in the hydrogen sulfide molecule.
So, Is H2S ionic or covalent? H2S is a covalent compound, since, both atoms (hydrogen and sulfur) are nonmetal in nature and linked together by a covalent bond. Also, the difference in electronegativity between sulfur (S) and hydrogen (H) atoms on the Pauling scale is not big enough to make an ionic bond in the H2S compound.
|Name of Molecule||Hydrogen sulfide|
|Molar mass||34.08 g/mol|
Why H2S is an covalent compound?
A covalent bond is formed when sharing of electrons is done between the atoms to achieve the noble gas configuration and attain stability.
Usually, covalent bonds are formed between the two nonmetals, between p-block and p-block, and formed when the electronegativity difference between atoms exists less than 1.7.
Hydrogen sulfide (H2S) is a covalent compound. Because the bond forms between two hydrogens and one sulfur are covalent in nature. The covalent bond is formed due to the sharing of an electron that occurs between hydrogen (H) and sulfur (S) atoms in order to complete their octet shell and hence, attain stability.
Every atom wants to attain stability either by sharing electrons or completing the transfer of electrons. Only the nature of the bond is changed as if the sharing of electrons occurs between atoms then the bond is formed called a covalent bond.
Same as when a complete transfer of electrons occurs between the atoms then the bond is formed which is called an ionic bond.
Examples of some compounds that form covalent bonds – are H2O, SO2, NH3, NO2, AlCl3, etc.
How covalent bond is formed in H2S?
The covalent bond is formed in H2S because of sharing of electrons occurs between hydrogen and a sulfur atom.
Let’s see how covalent bond formation takes place in H2S.
First of all, there are two types of atoms present in the H2S molecules – hydrogen and a sulfur atom.
⇒ The hydrogen atom is a nonmetal that belongs to Group I in the periodic table and has only one valence electron in the outermost shell.
⇒ The sulfur atom is a nonmetal that belongs to Group 16 or 6A in the periodic table and has six valence electrons in the outermost shell.
Every atom wants to complete its octet i.e. having 8 electrons in the outermost shell and attaining stability. Atoms can complete their octet by bonding with other elements or atoms with the help of either sharing of electrons or the complete transfer of electrons.
In the case of an H2S molecule, when hydrogen and sulfur atoms are placed together, they will share the electrons with each other to complete their octet and hence, makes a covalent bond.
Note: The hydrogen atom has only one valence electron and for completing the octet it needs one more electron.
Hydrogen atom is an exception to the octet as it needs only two electrons to complete the octet.
And the sulfur atom has 6 valence electrons in its outermost shell and it needs 2 more electrons to complete its octet.
Hence, both hydrogen and sulfur will share the electrons with each other and due to this, a bond is formed between them which is called a covalent bond.
As we see in the above figure of covalent bond formation in H2S, hydrogen atoms have one valence electron represented as an orange dot, and sulfur has six valence electrons represented as blue dots in their outermost shell.
The hydrogen atom needs one more electron and the sulfur atom needs two more electrons to complete the octet, hence, both of these will share the valence electron each other.
Therefore, the sharing of electrons between hydrogen and sulfur atom makes a covalent bond in the H2S molecule.
Note: The lone pair electrons can never take parts in chemical bonding or they never share electrons with any of the atoms. The shared pair of electrons is also called bonded pair of electrons.
Why is H2S not a ionic compound?
H2S is not an ionic compound because the bond formed between hydrogen and sulfur is due to sharing of electrons. In ionic compounds, the bond is formed between two atoms by the exchange of electrons from one atom to another.
There is no sharing of electrons involved in ionic compounds. Also, ionic compounds are mostly formed between one metal and another nonmetal. Usually, the electron is completely transferred from the metal atom to the nonmetal in an ionic compound.
In the case of an H2S molecule, the bond formed between hydrogen and sulfur is due to the sharing of electrons. There is no transfer of electrons involved from one atom to another atom in the H2S compound that’s why it forms a covalent bond instead of an ionic bond.
Also, both hydrogen and sulfur atoms are nonmetal and belongs to the p-block in the periodic table, hence, two nonmetal atoms reacting with each other form the covalent bond due to sharing of electrons involved in them.
There are more reasons why H2S forms a covalent bond and not an ionic bond?
⇒ The electronegativity of the sulfur atom is = 2.58
⇒ The electronegativity of the hydrogen atom is = 2.2
∴ The difference in the electronegativity between hydrogen and sulfur atom is = 0.38
According to the Pauling scale of electronegativity-
- If the difference of electronegativity between the two atoms exists less than 1.7, then the bond formed between these atoms is covalent in nature.
- If the difference of electronegativity between the two atoms exists more than 1.7, then the bond formed between these atoms is ionic in nature.
So, in the case of the H2S molecules, the difference of electronegativity between hydrogen and sulfur atoms is 0.38 which is way lesser than 1.7, hence, the bond formed between the atoms of the H2S molecule is covalent in nature.
Examples of some ionic compounds – MgO, Na2O, MgCl2, NaCl, etc.
Is H2S pure covalent compound?
So, Is H2S a pure covalent bond? No, it is not. First of all, understand the actual means of a pure covalent bond.
We know, that H2S is a covalent compound but whether it is pure or not that depends on the sharing of electrons that occur between the atoms(hydrogen and sulfur).
A pure covalent bond is formed when the electronegativity values of the two or more atoms in a molecule are the same. If the electronegativity value is the same for atoms, then the sharing of electrons between them is also equal, hence, the bond forms between them are pure covalent in nature.
In short, a pure covalent bond is formed between the atoms when they share an equal number of electrons.
But H2S is not a pure covalent compound because the difference in electronegativity value in hydrogen(2.2) and sulfur(2.58) caused unequal sharing of electrons between them.
The electrons are more shared towards the sulfur atom as it is more electronegative than hydrogen, hence, unequal sharing of electrons occurs in the H2S compound, which makes it a not pure covalent compound.
Is H2S polar covalent or nonpolar covalent compound?
A polar covalent bond is formed when the difference between the electronegativity of atoms, results in between 0.4 to 1.7. Also, in a polar covalent bond, there is unequal sharing of electrons occurs due to the difference in the electronegativity value of atoms.
Due to unequal sharing of electrons, a positive and negative charge is induced on the atoms that generate a dipole moment, and the bond formed between them is called a polar bond.
A nonpolar covalent bond is formed when the difference between the electronegativity of atoms is less than 0.4. Also, in a nonpolar covalent bond, there is equal sharing of electrons occurs due to the very little difference in the electronegativity value of atoms.
There are no charges induced in a nonpolar covalent compound
So, Is H2S a polar covalent or nonpolar covalent compound? H2S is a slightly polar covalent compound because sulfur is more electronegative than hydrogen, hence, it attracts more electrons towards itself. This induces a negative charge on the sulfur atom and a slightly positive charge on the hydrogen atom.
The separation of charges generates the dipole moment directed from positive to negative, hence, due to all these a bond is formed between sulfur and hydrogen, which is called a polar bond.
Properties of Hydrogen sulfide
- H2S is slightly denser than air.
- The hydrogen sulfide chemical formula is H2S or SH2.
- It has a molar mass of 34.08 g·mol−1
- H2S has a boiling point of −60 °C and a melting point of −82 °C.
- It has a pungent smell, like rotten eggs.
- It has a vapor pressure of 1740 kPa.
- H2S magnetic susceptibility is −25.5·10−6 cm3/mol.
- Hydrogen sulfide act as a reducing agent.
- Its refractive index is 1.000644
Uses of Hydrogen sulfide
- It is used to produce sulfur and sulfuric acid.
- It is used to produce pesticides, leather, and pharmaceuticals.
- It is also used in nuclear power plants for the production of heavy water.
- H2S is used in chemical analysis.
- It can also be used in agriculture as a disinfectant.
That’s all, we have done almost all concepts and possible explanations about Is water (H2S) ionic or covalent? Bond types in H2S, why H2S is covalent and not an ionic compound? How covalent bond is formed in water (H2S)? Are covalent bond forms in H2S molecule polar or nonpolar in nature?
Let’s take a quick overview of all the things we have studied in this article.
- Is Hydrogen sulfide (H2S) ionic or covalent? H2S is a covalent compound. Because the difference in electronegativity between hydrogen (H) and sulfur (S) causes unequal sharing of electrons that leads to the formation of the covalent bond between them.
- The covalent bond formed in the H2S molecule is slightly polar in nature.
- H2S is not a pure covalent compound because of the unequal sharing of electrons between the atoms.
- H2S is not a 100% covalent compound, it has some ionic bond character as well.
- The difference in electronegativity between Sulfur (S) and Hydrogen (H) is 2.58–2.2=0.38 which is lower than 1.7, hence, according to the Pauling scale, the bond formed between sulfur (S) and hydrogen (H) atom is covalent, that makes, H2S compound, covalent in nature.