[Chemistry Class Notes] on Difference Between Polar and Nonpolar Pdf for Exam

The polarity and Non-polarity of molecules depend upon electronegativity. The theory of electronegativity lies in entire inorganic chemistry. The more electronegative an atom, the more it seeks electrons. If one atom is more electronegative than others, it can form an ionic bond or a polar covalent bond. The formation of an ionic bond happens when a major electronegative atom takes an electron completely from another molecule. If the atom simply pulls the electrons towards itself and it forms a polar covalent bond. Thus, the disparate sharing of electrons results in the bond possessing a partial positive and negative end.

Identification of Polar and Nonpolar Bonds

As mentioned earlier, there could be the possibilities of two types of bonds, either it could be completely polar or nonpolar. When there is no disparity between the electronegativities of molecules, the bond will be nonpolar covalent bonds. On the other hand, when the more electronegative atom pulls an electron from the other atom, then polar ionic bonds will be formed.

Bond identification is represented in a tabular format below in terms of electronegativity:

The difference in Electronegativity is the major reason due to the difference between polar and nonpolar bonds.

Polar vs Nonpolar 

A compound may possess polar covalent bonds, but it may not be a polar compound. The reason behind it, due to the presence of net dipoles in a polar compound, they are asymmetrically arrayed. Take an example of water; it is a polar compound. They possess both a partial positive charge and which cannot cancel out.

 

Whereas, non-polar compounds can either share entire electrons or possess symmetrical polar bonds that can cancel out some sort of net dipole. Take an example of Boron Trifluoride (BF₃), where the polar bonds are arrayed in a single plane, and they end up cancelling out each other.

A tabular format is given below while differentiating both compounds:

Difference between Polar and Nonpolar Compounds

To understand the difference between polar and nonpolar compounds, it is necessary to concentrate upon the Lewis structure. The non-polar compounds will be symmetric, which means the presence of identical atoms around the central atom, which bonds to the element without any unshared pairs of electrons. While taking into consideration the CCl₄ molecule, it is completely non-polar due to its tetrahedral structure.

As compared to the non-polar compounds, polar compounds are asymmetric in nature as they contain lone pairs of electrons on a central atom, and the attached atoms possess different electronegativities. For example, Hydrogen Fluoride (HF) is a diatomic molecule, with one side being slightly positive, and another side being slightly negative. This disparity in electronegativity makes it a polar compound. The bond is a polar covalent bond. 

The high electronegativity of the Fluorine atom drags all the positive charges from the H atom. This is why a partial positive charge has been generated on the H atom and a partial negative charge on the F atom. The entire molecule is considered a dipole molecule due to the unequal distribution of electron density. 

Another important thing that should be considered while determining polar and nonpolar molecules is molecular geometry. Due to the linear structure of the CO₂ molecule, the higher electronegative oxygen atoms drag the charges from the carbon atom and thus two isolated dipoles pointing outward from the carbon atom to the oxygen atom so that the dipoles cancel out each other, and the molecular polarity of CO₂ becomes zero. CO₂ is a nonpolar molecule.

Whereas water possesses a bent structure and due to the higher electronegativity of oxygen, it pulls out the charges and so that the direct will be H to O. Due to this structure, the dipoles cannot cancel out each other and the compound is polar. 

This represents the molecular geometry that affects the polarity. CO₂ possesses zero dipole moment due to the linear structure and it becomes a nonpolar molecule. In contrast, water is a polar compound due to its bent structure and dipole moment cannot get zero   

Difference between polar and non-polar solvents

The prime difference between polar and nonpolar solvents is, the polar solvent gets dissolved in a polar compound, whereas the non-polar solvent gets dissolved in non-polar compounds. Well, moreover, the polar solvents possess molecules with polar bonds, and nonpolar solvents possess molecules with similar electronegativity values. 

What are Polar Solvents?

Generally, polar molecules and polar solvents possess large dipole moment values. Polar solvents are liquids that can dissolve various polar compounds. This is because the positively charged molecule of a compound gets easily attracted by the negatively charged molecule of a solvent, which leads to the liquefaction of the polar compounds to the polar solvents. It is previously illustrated that the polarity of the solvent arises because of disparity in the electronegativity of molecules.  

What are non-polar solvents?

The non-polar solvents are liquids that do not have any dipole moment. These non-polar solvents do not possess any partial positive or negative charges. That is why non-polar solvents are unable to dissolve polar compounds as there is the absence of opposite charges to attract the polar ones. 

Hence we come to know that after going through the article that Polar molecules are the result of differences in electronegativity between the atoms from which molecules are made. Nonpolar molecules are formed when electrons are shared equally between atoms of a molecule.
The article discusses the difference between polar and nonpolar bonding, compounds and solvents in detail.