Question

What’s the difference between polarity/ nonpolarity in bonds vs. polarity/ nonpolarity in molecules? How do you determine if a bond or molecule is polar or nonpolar?

Answer 1

Answer: Formation of chemical bond(s) between the atoms and molecules are essential for the existence of the constituents (atom or molecules). The bonds formed between them may result from the electrostatic force of attraction between the oppositely charged ions or sharing of electrons between the atoms. Every atom has the tendency to attract or share the pair of the electron (covalent bonds) towards itself. This attraction/ sharing of electrons by the atoms depend on their electronegativity (fundamental property of an atom). When one atom is more electronegative than another atom, then that atom can pull the shared electrons closer to itself and it develops a slightly negative charge simultaneously the other atom release it electrons and develop a slightly positive charge. This combination of slight negative and slight positive charges among the atoms responsible for the development of polarity on the molecules. If the sharing atoms have almost the same electronegativity then there is no chance of development of polarity on the molecule.

Example; Non-polar bond- Sharing of electrons between the dimeric molecules (H₂, O₂, Cl₂ etc.), The electronegativity of both the atoms are same, so there is no chance for the development of any charge among the atoms and molecules remain non-polar

Polar bond- Sharing of electrons between the heterodimeric or heteromultimeric molecules. In this type of bond, the involving atoms have different electronegativity based on that they attract/ release the sharing electrons and develop the respective charges and development of polar bond takes place. Example- HCl, NaCl etc.

Polar molecule- H₂O, H₂S

Non-polar molecules- CO₂

Details see in the figure attached