Non-polar Molecules

Non-polar molecules lack charge at the ends of the molecule. These molecules, instead, have electrons dispersed equally and are symmetrical all over. The electrons of the molecules cancel each other and are finely distributed. 

Non-polar molecules do not have separate molecular charges and lack the positive and negative poles, unlike polar molecules. Non-polar molecules can dissolve in non-polar solvents like organic solvents. Some of the examples of non-polar molecules are ozone, nitrogen, oxygen, methane, etc.

What is polarity?

A chemical polarity is the formation of the electric dipole due to the separation of the electric charges. The poles of the molecule can contain a positive or a negative charge. The polarity of the molecule is defined by the melting point, boiling point, surface tension and solubility of the molecule. 

Chemical polarity can be polar or non-polar and is subject to dipole and the molecular dipole moments of the molecule. The presence of the negative and positive charges, chemical bonds and the sharing of electrons make a molecule polar and non-polar.

Types of chemical polarity

Non-polar bonds have no positive or negative charges in them and are symmetrical in shape. The electrons of the diatomic molecules are shared equally between the two atoms and the bonds are cancelled. In the covalent bond between the two atoms of the molecule, the electrons are shared equally resulting in no net electrical charge. Majorly, the true non-polar molecules are formed by the covalent bonding between the two similar atoms. Examples of non-polar molecules are benzene, carbon dioxide, noble gases, etc. 

Polar molecules are formed when the atoms of the molecules do not share the electrons equally and the electric charges are dispersed unequally in the molecule. The part of the molecule contains the positive charge, while some other part contains a negative charge. The uneven electron and charge distribution are due to the difference between the electronegativity. Examples of polar molecules are ethanol, water, ammonia, etc.

How is polarity determined?

The presence of the covalent bond and electronegativity difference defines the polarity of the molecule. The sharing of electrons between the atoms of the same element or of different types determines the polarity of the molecule. The dipole developed due to the spread of the electron and charges defines the polar and the non-polar molecule. 

In polar molecules, the bond dipole does not cancel each other. In contrast, in a non-polar molecule, the bond dipole gets cancelled. Also, a polar molecule must have at least one polar covalent bond in them. The electronegativity of the molecule is the major factor that influences the polarity and is the ability of the atom to attract the electron involved in the chemical bond. The bonds having electronegativity less than 0.4 are polar and between 0.4 to 107 are polar.  

Molecular polarity of non-polar molecules

The atoms of the non-polar molecules are identical and attached to the central atom of the molecule in the absence of any unshared pairs of electrons. The geometrical structure of the molecule will be in symmetry as the electrons between the atoms of the molecules are shared equally. The electronegativity difference decides the polarity as the lower the difference, the less will be the ionic bond and the molecules are more likely to be non-polar. 

Examples of non-polar molecules

• Non-polar molecules include the atoms of the noble gases, namely, helium, neon, argon, krypton and xenon.
• A homonuclear diatomic element like oxygen, nitrogen, hydrogen, etc.
• Most of the organic compounds
• Benzene, methane, carbon tetrachloride, carbon dioxide, ethylene, etc.
• Hydrocarbons containing liquids like toluene and gasoline

Polarity and solubility

The polar and the non-polar nature of the molecule can be used for determining the solubility to form a solution. The dissolving properties follow the rule of like dissolves like and hence, polar molecules get dissolved in the polar solvent and non-polar molecules get dissolved in the non-polar solvent. The mixing of one polar and another non-polar will not dissolve the molecule like the water being polar and oil being the non-polar do not get dissolved in each other. 

Conclusion

The polarity of the molecule can form a polar or a non-polar molecule that is based on the factors like electronegativity, dipole moments and the electron sharing of the atoms. The equal and the unequal sharing of the electrons, the distribution of the electric charge in the molecule and the polar bonds determine the polarity of the molecule. 

Non-polar molecules are symmetrical and have electrons shared equally. Non-polar molecules get dissolved in the non-polar solvent like organic solvent. Examples of non-polar molecules are noble gases, oxygen, nitrogen, chloride, benzene, carbon dioxide, carbon tetrachloride, etc.