polar

[josmit_1D]

how do you know if a molecule is polar or nonpolar?

[Jason Wu 1E]

A molecule is considered polar if the net dipole moment yields zero. As in the case of CO2, the dipole moments yield zero because the molecular structure is linear. In the case of H2O, because the molecule is bent by the lone pairs on the Oxygen atom, there is a net dipole moment and thus the molecule is polar.

[Kehlin Hayes 4C]

A polar molecule has a partial charge associated with them because of the unequal sharing of electron that results in the molecule having an either positive or negative overall charge.

[Fdonovan 3D]

Generally, if two atoms have similar electronegativities (such as C and H that both have half full valence shells) then they will form a nonpolar covalent bond since neither has more pull on the electrons. In contrast, atoms with fairly different electronegativities (such as H and O) form polar bonds since the oxygen's affinity for electrons causes greater pull on them resulting in a partial negative charge. I believe the general rule is that if the electronegativity is greater than 2, it'll be polar, and if its less than 1.5, it'll be nonpolar.