Polar or nonpolar, H2S?

When discussing a molecule, it is necessary to identify its primary structural components. Which element is the most electronegative? How are its atoms arranged? Having so many questions piques your curiosity to learn their answers.

Hydrogen sulphide is a molecule without colour that has the chemical formula H2S. It is toxic and smells like a rotting egg.

So, is hydrogen sulphide polar or nonpolar? H2S is slightly polar due to its bent-shaped geometrical structure and the minor difference in electronegativity between Hydrogen(2.2) and Sulfur(2.58), which results in a non-zero dipole moment.

Other H2S qualities include:

It interacts quickly with metal ions to form metal sulphides.

It is hazardous and poisonous, particularly for oxygen inhalers.

As a corrosive, it destroys metals such as copper, which turns green after the reaction.

In the year 177, a chemist named Carl Wilhelm Scheele discovered it. The human body produces this gas and uses it as a signalling molecule.

What is the definition of polarity?

Polarity is defined as the distribution of electrons within a molecule. It reveals how the most electronegative atom attracts and repels electrons.

However, how does one evaluate the polarity of the element? Let’s determine this by studying a few facts about the idea of electronegativity, which is relevant to polarity.

Electronegativity describes an element’s capacity to attract electrons. Consequently, elements that attract more electrons will have a greater electronegative charge.

Electronegativity is used to assess the polarity of a molecule by determining the distribution of electrons.

Describe a polar molecule.

Since molecules are neutral, they are termed polarised when one side has a greater negative charge than the other side.

Atoms are arranged asymmetrically, and there is an unequal distribution of negative charges (electrons) surrounding the core atom.

For instance-

Water (H2O) is a polar molecule because the more electronegative Oxygen has a greater concentration of electrons than the positively charged Hydrogen, which is the other element in the molecule.

You can investigate the cause of H2O’s polarity.

Other molecules, such as SO2, NH3, etc., are polar molecules as well.

Behind nonpolar molecules such as CO2, you can investigate the explanation for CO2’s nonpolarity.

How can polar molecules be distinguished from non-polar molecules?

The polar molecules have an uneven distribution of electrons, indicating that the charges are unbalanced. But in non-polar compounds, the number of electrons is relatively equal.

For instance-

You are aware that oxygen (O=O) is very electronegative but non-polar. Why?

Both atoms in the molecule O2 have the same electronegativity density, which means they share the same number of electrons. Therefore, the O2 molecule is nonpolar. Dipoles are molecules composed of the same sort of elements, such as H2, N2, Cl2, etc.

They are non-polar molecules by default. Hydrocarbons containing hydrogen and carbon, such as methane (CH4), ethane (C2H6), etc., are also known as non-polar molecules.

How can the polarity of H2S be tested?

Before determining the polarity of the H2S molecule, let’s examine its bond polarity. Calculating the polarity of a link when atoms of a molecule have partial positive and negative charges.

Relevance of Electronegativeness

If the difference in electronegativity between the two elements is higher than or equal to 0.5, the bond is polar.

With atomic number 16, Sulfur attracts both of Hydrogen’s electrons to complete its outermost shell and acquire a negative charge.

Hydrogen gains a positive electric charge. Therefore, the electronegativity of Sulfur is greater than that of Hydrogen.

As you know, electronegativity increases from left to right and declines from top to bottom in the periodic table.

Hydrogen and sulphur have electronegativity values of 2.20 and 2.58, respectively. Their difference in electronegativity, 0.38, is less than 0.5. Consequently, H2S is a nonpolar bond.

Because it is more electronegative than Hydrogen, Sulfur is partially negative. As a result, it forms a dipole moment.

In addition, the dipole moment is represented as an arrow pointing toward an atom with a greater electronegative charge. The dipole moment of the H2S compound is expressed by Hydrogen (delta +) to Sulfur (delta-).

The significance of geometrical form

To establish the polarity of any molecule, such as H2S, it is essential to determine its outside atoms and shape.

There are two pairs of lone electrons on the core sulphur atom, which causes the H-S bond to be curved. Therefore, the molecule is asymmetric due to the odd distribution of atoms around its centre atom.

Due to its curved shape, a dipole moment is produced between the H-S bonds. The larger the charge separation, the bigger the atomic dipole moment. Sulfur therefore attracts additional electrons and has a partial negative charge.

Hydrogen has a partial positive charge as there are now fewer positive charges remaining.

The dipole moment is a vector quantity since it has both direction and magnitude. It points in the direction of more electronegative atoms.

When the arrows do not cancel each other out, the molecule is said to be polar.

The significance of Dipole Moment

The polarity of a molecule is indicated by its dipole factor. The greater a molecule’s polarity, the greater its dipole moment.

It can alternatively be described as the product of two atoms’ charges and their distance apart.

D = Q * R

D = dipole moment

Q = charge on atomic nuclei

R = separation between them

Utilizations of H2S

It is utilised in the production of hydrogen and sulfuric acid.

It is frequently employed in the industrial production of several inorganic chemicals.

It is employed in the mass production of insecticides for agricultural crops.

Hydrogen sulphide is utilised extensively in nuclear power reactors as heavy water.


Before reaching a conclusion regarding the polarity of any molecule, a number of elements must be taken into account.

How does bond polarity affect a molecule’s polarity?

How to detect the polarity orientation of a molecule?

Does form influence polarity?

How do symmetrical and asymmetrical contribute determine a molecule’s polarity?

H2S is the polar molecule containing Hydrogen atoms that are covalently bound to the sulphur atom. It has an asymmetrically bent form that generates a dipole moment among atoms.

Hydrogen is more electronegative than Sulfur. This refers to the fact that sulphur has more electrons than oxygen.

As you are aware, the electronegative difference of the molecule H2S is 0.4, which is minimal and has a weak polarity as well.

Due to the lack of polarity between the atoms, technically speaking, H2S is a non-polar molecule.

This is an exceptional instance that must be tallied. Certain studies indicate that for a molecule to be polar, its electronegativity must fall between 0.5 and 2.

To have a thorough understanding of the electronic structure of H2S, you must also read articles on its lewis structure, geometry, and hybridization.


Question 1: Name the compounds with polar bonds.

A1. Polar bonding chemicals include water (H2O), ammonia (MH3), and sulphur dioxide (SO2) (SO2).

What constitutes a dipole moment? How do you compute its magnitude?

A2. A dipole moment is depicted by a customised arrow that extends from a partially positive end to a partially negative side.

For molecules containing more than two atoms, there are two possible outcomes:

a) When the dipole moment is nullified, or when the arrows point in opposite directions, its magnitude is equal to zero. The molecule lacks polarity.

b) The arrows connecting the core atom to the surrounding atoms point either away from or toward the central atom. When the magnitude of the dipole moment is greater than zero, the molecule is polar.

Record the electronegativity of each element.

A3. Oxygen- 3.44

Magnesium- 1.31

Sodium- 3.16

Sodium- 0.93

Calculate the difference in electronegativity between molecules of CH4 and CO2.

A4. a) CH4

Carbon- 2.55, Hydrogen- 2.20

Electronegative distinction is-

2.55-2.20= 0.35

CH4 is a non-polar molecule because the atoms’ dipole moments cancel each other out.

b) SO2

Sulfur- 2.58, Oxygen- 3.44

Electronegative distinction is-

3.44- 2.58= 0.86

CO2 is a polar molecule due to the fact that the atoms’ dipole moments do not cancel each other out, and their magnitude is greater than 0.

Read more: MO Diagram, NO2 Lewis Structure, Molecular Geometry, Hybridization, and Polarity

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


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