What is a polar molecule?

A polar molecule is defined by the presence of polar bonds that create a net dipole moment across the molecule. This occurs when there is an uneven distribution of electrical charge, often due to differences in electronegativity between the atoms involved in the bonds. In polar molecules, one end of the molecule has a partial negative charge while the other end has a partial positive charge, resulting from the atoms attracting the shared electrons to varying degrees.

The presence of polar bonds, which are formed between atoms with significantly different electronegativities, leads to this dipole moment. For example, in water (H₂O), the oxygen atom is more electronegative than the hydrogen atoms, drawing the electron density closer to itself and thereby creating a separation of charge within the molecule.

Understanding polar molecules is essential in predicting various chemical behaviors, such as solubility and reactivity. For example, polar molecules tend to dissolve well in polar solvents (like water) due to similar intermolecular forces, while non-polar substances do not.

Molecules that are entirely non-polar, do not possess any electronegativity, or have an even distribution of charge, do not meet the criteria of being polar.