Why do dipoles cancel out?

1 Answer
Nov 19, 2017

Well, not all of them do.....

Explanation:

Dipoles are vector quantities...and they have magnitude and direction, and are thus summed geometrically. The carbon dioxide molecule is definitely a species where there is charge separation between the carbon and the oxygen bonds....

#""^(-delta)O=stackrel(delta+)C=O^(delta-)#...but given the linear structure of this molecule #/_O-C-O=180^@#, the bond dipoles cancel out upon vector addition and to give a ZERO resultant, and #CO_2# is thus non-polar. For #""^(+delta)H-stackrel(delta-)O-H^(delta+)#, whose structure is bent, #/_H-O-H=104^@#, and the dipoles DO NOT geometrically sum to zero. Water is thus a polar molecule....