Many Great Thanks to Tina Nye of Carson High School for the original animated graphic! Thanks for your curiosity and your dedication.
According to the IUPAC naming rules we would name the above structure cyclo (ring) hexa (6 carbons ) atriene (3 double bonds). We then give the double bonds the lowest possible addresses. Which would be 1,3,5-cyclohexatriene. Excellent job!! Ah... but there is a proverbial fly in the ointment!
This structure could also be 2,4,6-cyclohexatriene. It turns out that this structure is both at the same time, or neither.
Some older references attempt to describe this by the bonds endlessly migrating on a quantum scale as illustrated by our first graphic. Since neither 1,3,5-cyclohexatriene nor 2,4,6-cyclohexatriene is exactly correct...
It is time for some fuzzy logic. The bonds do not actually migrate in sensu-stricto, rather the electrons are delocalized.
Well, blurry logic anyway. We typically draw this structure as a hexagonal ring with a circle in the middle. The circle in the middle represents the 3 double bonds that are distributed throughout the the ring. So if the IUPAC name doesn't really work, what are we do ???
Lets just agree to call it benzene most of the time.
Original graphics by Tina Nye. Again Thanks to Tina Nye (class of 08) for her tireless work rendering graphics. Good Luck at University.
The jellybean like p-orbitals merge to form a delocalized set of doughnut like pi-bonds. Sigma bonds are shown by the white bars connecting the carbons.
Other structure with multiple bonds exhibit resonance, such as nitrate ion:
This is much quicker than rendering 3-d graphics and how you show resonance with Lewis structures. Anytime you have more than one valid structure for a compound then that structure has resonance.