A simple note on Non-Polar Molecules

A nonpolar molecule does not have any separation of charges. We can say that the electrical charge of a nonpolar molecule is distributed evenly within. Generally, these molecules are formed when the electrons are shared equally between the atoms in a molecule. They are also formed when the electrons inside a molecule are arranged symmetrically so that the dipole charges cancel out each other. These molecules are hydrophobic and hence do not mix with water at room temperature, but they tend to mix well in non-polar solvents.

Determination of Polarity

The molecule’s polarity can be predicted by taking a look at the type of chemical bond formed between the atoms of the elements. In case the difference between the values of electronegativity of the atoms is noteworthy, then atoms will not share the electrons equally. In simple words, the electron affinity of one atom will be more than the other. A negative charge is carried by the atom that has the most electron affinity, and a positive charge will be carried by the atom that is not attractive to the electrons.

The consideration of the point group of the molecule helps in simplifying the prediction of the polarity. Generally, a molecule is said to be non-polar when its dipole moments cancel each other out. However, it will be polar if its dipole moments do not cancel out each other. In order to determine the polarity of a molecule that contains more than two atoms, then the geometry of the molecule must be taken into consideration.

Polar Molecules

In polar molecules, the unevenly distributed electrons induce an electric dipole moment. It means that a part of the molecule has a slight positive charge, whereas another part has a slight negative charge. However, the molecules that contain more than two atoms could be polar as well. Polar molecules are asymmetrical and the electrons are unevenly distributed. A polar molecule may have an ionic bond or a covalent bond. H2O, CHF3, NH3, etc., are some examples of polar molecules.

Difference between Polar and nonpolar molecules

The main difference between the polar and the non-polar molecules is that the distribution of electrons between the atoms is uneven in non-polar molecules and the unevenly distributed electrons induced electric dipole moment in polar molecules. A nonpolar molecule has a zero net dipole moment, and in polar molecules, a net dipole moment is present. In a polar molecule, the difference in electronegativity between the atoms is more than 0.4, and in a nonpolar molecule, it is less than 0.4. There is a high melting and boiling point in polar molecules and low melting and boiling point in non-polar molecules. There is a slightly negative and slightly positive charge in a polar molecule, but there are no positive or negative charges in a nonpolar molecule.

Examples of non-polar molecules

Oxygen (O2), nitrogen (N2) and ozone (O3) are some examples of homonuclear non-polar molecules. Carbon dioxide (CO2), toluene, and gasoline are some other non-polar molecules. Most of the carbon compounds are non-polar. However, carbon monoxide (CO) is an exception. Carbon monoxide is a linear molecule that has enough electronegativity between the carbon and oxygen molecules to make it a polar molecule. Alkynes are also considered non-polar molecules as they do not dissolve in water. The noble gases are also taken as non-polar because they contain a single atom of their element.

Nonpolar Molecules with Polar Bonds

The polarity of a molecule depends upon the values of electronegativity between the two atoms that form a chemical bond. Covalent bonds are formed by two atoms that have the same electronegativity. In a covalent bond, the electrons are shared evenly between the atoms. Polar covalent bonds are formed by atoms that have slightly different values of electronegativity. Frequently, it is seen that the polarity of the bonds is similar to the polarity of the molecules. Therefore, non-polar molecules with polar bonds and polar molecules with nonpolar bonds exist.

Conclusion

Non-polar molecules are formed when the atoms share the electrons equally or when the molecule has a symmetrical arrangement of electrons. These molecules do not mix with water and are called hydrophobic. In order to determine the polarity of the molecule, chemical bonds are taken into consideration. A non-polar molecule contains neither a negative nor a positive charge. Molecules are formed when atoms bond together and share electrons. The electrons are evenly distributed in non-polar molecules and the uneven distribution of electrons induced electric dipole moment in polar molecules. Carbon dioxide (CO2), oxygen (O2), and nitrogen (N2) are some examples of non-polar molecules.