When you play tug of war, one side usually wins, right? Well, it's the same with polar and non-polar covalent bonds. These types of bonds have shared electrons, which are represented by the ribbon in the game. In polar bonds, the electrons aren't shared equally between the two atoms. Instead, they're pulled towards one side, like the ribbon.

So, why does this happen? We'll explore that in this article. We'll also learn about the differences between polar and non-polar bonds, and their characteristics. We'll even touch on ionic character. And, to help you understand better, we'll give you examples of both types of bonds. Get ready to learn about the science of bonding!

What are Polar and Non-Polar Covalent Bonds?

In Covalent Bonding, we discovered that a covalent bond is created when two atoms share a pair of electrons. If the two atoms are the same, the electrons are shared evenly, forming a non-polar bond. But, if the two atoms are different, the electron pair might not be shared equally. This creates a polar bond, where one atom pulls the electrons towards itself more strongly.

So, what causes the uneven distribution of electrons in a polar bond? We'll explore that in this article. Understanding the science behind polar and non-polar covalent bonds is crucial for comprehending chemical reactions and properties. Let's dive deeper!

What Causes Polar Bonds?

We've learned that polar covalent bonds are formed when one atom in a covalent bond attracts the shared pair of electrons towards itself more strongly than the other. This is all to do with the atom's electronegativity.

Electronegativity is an atom's ability to attract a shared pair of electrons. We measure electronegativity on the Pauling scale. It runs from 0.79 to 3.98, with fluorine being the most electronegative element, and francium the least electronegative. (The Pauling scale is a relative scale, so don't worry about how we get these numbers for now).

‍

You can read more about this topic over at Electronegativity.

In covalent bonds, the more electronegative atom attracts the shared pair of electrons more strongly than the less electronegative atom. This creates partial charges in the atoms involved in the bond. The more electronegative atom becomes partially negatively charged, while the less electronegative atom becomes partially positively charged. Polar covalent bonds are formed between atoms with different electronegativities and have partial charges and dipole moments. Non-polar covalent bonds are formed between atoms with the same electronegativity and do not have any partial charges or dipole moments.

One example of a polar bond is the O-H bond in water (H2O). Oxygen is more electronegative than hydrogen, so it attracts the shared pair of electrons towards itself more strongly. As a result, oxygen becomes partially negatively charged, and hydrogen becomes partially positively charged. This creates a dipole moment in the molecule.

Understanding the characteristics of polar and non-polar covalent bonds is essential to comprehend chemical reactions and properties. In polar bonds, the atoms have partial charges and form molecules with dipole moments. In contrast, non-polar bonds involve atoms with no partial charges and form neutral molecules without dipole moments.

The Difference Between Polar, Non-Polar Covalent and Ionic Bonds

When it comes to bonding, it is hard to draw a line between polar, non-polar, and indeed even ionic bonding. To understand why, let's look more closely at one particular bond: the C-H bond.

Carbon has an electronegativity of 2.55; hydrogen has an electronegativity of 2.20. This means that they have an electronegativity difference of 0.35. We might guess that this forms a polar bond, but in actual fact, we consider the C-H bond to be non-polar. This is because the electronegativity difference between the two atoms is so small that it is essentially insignificant. We can assume that the electron pair is shared equally between the two atoms.

On the other hand, consider the Na-Cl bond. Sodium has an electronegativity of 0.93; chlorine has an electronegativity of 3.16. This means that they have an electronegativity difference of 2.23. This bond is polar. However, the electronegativity difference between the two atoms is so great that the electron pair is essentially completely transferred from sodium to chlorine. This transfer of electrons forms an ionic bond.

Visit Ionic Bonding for more on this subject.

Bonding falls on a spectrum. At one end, you have completely non-polar covalent bonds, formed between two identical atoms with the same electronegativity. At the other end, you have ionic bonds, formed between two atoms with an extremely large difference in electronegativity. Somewhere in the middle, you find polar covalent bonds, formed between two atoms with an intermediate difference in electronegativity. But where do we draw the limits?

If two atoms have an electronegativity difference of 0.4 or less, they form a non-polar covalent bond. If two atoms have an electronegativity difference between 0.4 and 1.8, they form a polar covalent bond. If two atoms have an electronegativity difference of more than 1.8, they form an ionic bond.

We can say that the bond has an ionic character proportional to the difference in electronegativity between the two atoms. As you might be able to guess, atoms with a larger difference in electronegativity show more ionic character; atoms with a smaller difference in electronegativity show less ionic character.

‍

Predicting Bonding from Elemental Properties

In summary, bonding can be classified as non-polar covalent, polar covalent, and ionic, but these classifications don't always hold true. The properties of a compound can help determine the type of bonding present. Ionic compounds have high melting and boiling points, are brittle, and conduct electricity when molten or aqueous. Covalent small molecules have low melting and boiling points and don't conduct electricity. Electronegativity differences can also indicate the type of bond present, but looking at properties is often a more reliable way to determine bonding.

List of Polar and Non-Polar Covalent Bonds

Let's end with some examples of polar and non-polar covalent bonds. Here's a handy table that should help you.

That's all! You should now be able to state the difference between polar and non-polar covalent bonding, explain how and why polar bonds are formed, and predict whether a bond is polar or non-polar based on the properties of the molecule.

Polar and Non-Polar Covalent Bonds - Key takeaways A covalent bond is a shared pair of electrons. A non-polar covalent bond is a bond in which the electron pair is shared equally between the two bonded atoms, while a polar covalent bond is a bond in which the electron pair is shared unequally between the two bonded atoms. Polar bonds are caused by differences in electronegativity. The more electronegative atom becomes partially negatively charged, and the less electronegative atom becomes partially positively charged. Bonding is a spectrum, with non-polar covalent bonding at one end and ionic bonding at the other. Most bonding falls somewhere in between, and we say that these bonds show ionic character. We can use differences in electronegativity to predict the dipole moment. However, this isn't always the case; looking at a molecular species' physical properties can be a more accurate way of determining its bonding.

Polar and Non-Polar Covalent Bonds

What is the difference between non-polar and polar covalent bonds? 

In non-polar covalent bonds, the bonded electron pair is shared equally between the two atoms. In polar covalent bonds, the bonded electron pair is shared unequally between the two atoms. This occurs in bonds formed between two atoms with different electronegativities.

What are examples of polar and non-polar bonds?

Examples of non-polar bonds include C-C and C-H bonds. Examples of polar bonds include C-O and O-H bonds.

How are covalent polar and non-polar bonds formed?

Non-polar covalent bonds are formed between atoms with the same electronegativity. They share the bonded electron pair equally between them. In contrast, polar covalent bonds are formed between two atoms with different electronegativities. One atom attracts the bonded pair of electrons more strongly than the other, meaning the electron pair is shared unequally between the two atoms.

Why are covalent bonds polar or non-polar? 

The polarity of a covalent bond is all to do with the electronegativities of the atoms involved, as this is a measure of how well they attract the shared pair of electrons. Two bonded atoms with the same electronegativity form a non-polar bond, as they both attract the shared pair of electrons equally. Two atoms with different electronegativities form a polar bond, as one atom attracts the shared pair of electrons more strongly than the other.

How do you determine polar and non-polar covalent bonds?

To determine the polarity of a covalent bond, look at the electronegativity difference of the two atoms involved in the bond. An electronegativity difference of less than 0.4 results in a non-polar bond, while an electronegativity difference of greater than 0.4 results in a polar bond.

‍