When the Snake Bites its Own Tail

-

 

Carbon is a fairly social atom. It forms 4 links with other atoms to make up molecules. By comparison, oxygen looks a bit shy with only 2 links. And hydrogen is like introvert bordering on antisocial. Only one link!

These three atoms form some of the most useful and common molecules. Water is H2O. We can show the 2 links between atoms by writing it like this: H-O-H. Similarly, carbon dioxide or CO2 is in fact O=C=O. Carbon has 4 links, the oxygens have 2 links each, no worries.

Carbon and hydrogen compounds are called alkanes. The simplest is natural gas or methane, CH4. Propane has a a chain of 3 carbon atoms. It is C3H8. Petrol is mostly octane with a chain of 8 carbon atoms, C8H18. Generally speaking, for a chain of n carbon atoms C, we need twice that number of H, plus one at each end. That is 2 x n + 2. Simple enough?

Enter the benzene. 

Back in 1865, August Kekule scratched his head on this one. With 6 carbon atoms, it should be C6H14 right? Wrong. The study of molecular mass shows C6H6. How can that be? Screw this, August said, I am going to have a nap. And he had a dream of a snake biting its own tail. He woke up and said aha! What if the carbon chain is a circle, or better a hexagon? Again everyone is stable and happy. It’s amazing how sometimes intuition and dreams can help science.

Comments

Post a Comment

Popular posts from this blog

Blue is Hot

-
Image
  Kawah Ijen Volcano Where the expression “ red-hot ” comes from? To work a piece of steel, a blacksmith puts it in burning charcoals (more red) and activates the blower until the iron becomes red hot. So red is hot, OK? End of story. Well, maybe not. In the good old days, we had tungsten filaments globes and power brownouts. When this happened, the lights looked reddish brown because of low power. When the good 240V came back, surely the lights looked white again. Besides the blue flame of any gas cooker, I thought of two examples of very hot blue things. The first one is a weird volcano in Indonesia called Kawah Ijen. In most volcanoes the lava that comes out is red-orange melted rock, or magma. This is pretty hot stuff, 700 to 1,250 degrees C. But Kawah Ijen beats that. Its lava spits out blue flames of burning sulphur, at about 6,000 degrees C. Most unusual. The second one is a star. If you look at the Western horizon after sunset at the moment, you can ’ t miss the Orio...
Read more

Le Plantain (Plantago)

-
Image
      This stuff grows everywhere. In parking lots, on walls and even on my garden. Now that says something because I am a very bad gardener! There is some in the grass around my house too and the sheep just ignore it. What a pest! So I looked at ways to get rid of it. Instead, I found that various species of this plant grows on all continents and has been used as a medicinal plant since prehistoric times. You know, if the Dakota Indian tribe used it to cure snake bites, it was not to spread misinformation among white Yank settlers. They did it because it works. Among many other things, it is astringent, anti-toxic and anti-inflammatory. For topical applications, a poultice can be used on wounds and cuts and it promotes a very quick healing. So I decided to give it a go. The variety that grows in our garden is Ribwort plantain (Plantago lanceolata). A few weeks ago, my wife grabbed most of it. The leaves were washed, then cut to small pieces in a food processor...
Read more