Answer in units of ◦C.? The answers given cover everything, but I want to make it more clear that the resonance effect mentioned by Abhijit means that the electrostatic forces on each carbon atom within the benzene molecule are exactly the same. It has many real-world uses. Many medicines contain parts made from benzene. It is used as an additive in gasoline, plastics, synthetic rubber, dyes and it is an industrial solvent, which means it can dissolve many other chemical molecules. Because the electrons are no longer held between just two carbon atoms, but are spread over the whole ring, the electrons are said to be delocalised. Get your answers by asking now. It is a regular hexagon because all the bonds are identical. What would happen if you did not add acid after exactly 15 minutes of the enzymatic reaction in a competition ELISA?  Other scientists wrote articles to support this view in Nature in 1987. Benzene has special properties called aromaticity. A 676 mL gas sample at STP is compressed to Problems with the stability of benzene. , From Simple English Wikipedia, the free encyclopedia, bonding in benzene – the Kekulé structure, "Unicode Character 'BENZENE RING' (U+232C)", "Unicode Character 'BENZENE RING WITH CIRCLE' (U+23E3)", https://simple.wikipedia.org/w/index.php?title=Benzene&oldid=6596424, Creative Commons Attribution/Share-Alike License. (You have to know that - counting bonds to find out how many hydrogens to add doesn't work in this particular case.). Don't worry about single bond and double bond lengths because there aren't any single bonds or double bonds. What is the new pressure...? The other four delocalised electrons live in two similar (but not identical) molecular orbitals. The remaining p orbital is at right angles to them. If you added other atoms to a benzene ring you would have to use some of the delocalised electrons to join the new atoms to the ring. Notice that the p electron on each carbon atom is overlapping with those on both sides of it. You will need to use the BACK BUTTON on your browser to come back here afterwards. Benzene is built from hydrogen atoms (1s 1) and carbon atoms (1s 2 2s 2 2p x 1 2p y 1).. Each carbon atom has to join to three other atoms (one hydrogen and two carbons) and doesn't have enough unpaired electrons to form the required number of bonds, so it needs to promote one of the 2s 2 pair into the empty 2p z orbital. You can also read about the evidence which leads to the structure described in this article. Benzene is a planar regular hexagon, with bond angles of 120°. The circle within the second formula indicates that all C—C bonds in the hexagon are equivalent. If benzene had three double bonds, three sides of its ring would be shorter than the other three sides. The delocalization of electrons is one explanation for the thermodynamic stability of benzene and related aromatic compounds. It is the overlap of p-orbitals both above and below the ring that produces the pi clouds. They showed that the electrons in benzene are almost certainly localized to particular carbon atoms. The next diagram shows the sigma bonds formed, but for the moment leaves the p orbitals alone. X-ray diffraction shows that all of six carbon-carbon bonds in benzene are of the same length of 140 picometres (pm). The carbon atom is now said to be in an excited state. Benzene bond length.... Don't worry about single bond and double bond lengths because there aren't any single bonds or double bonds. (In other words, the molecule's double bonds switch quickly between pairs of carbon atoms.) There is only a small energy gap between the 2s and 2p orbitals, and an electron is promoted from the 2s to the empty 2p to give 4 unpaired electrons. Each carbon atom has to join to three other atoms (one hydrogen and two carbons) and doesn't have enough unpaired electrons to form the required number of bonds, so it needs to promote one of the 2s2 pair into the empty 2pz orbital.