Montshire Minute: Carbon

Originally aired during the week of November 26, 2001

Monday

Hi this is Neal, and I'm here to talk to you about . . . you know . . . the little talk that we need to have at some point in our lives. THE talk. About life. The birds, the bees. So please bear with me. What I'm trying to say is, life as we know it . . . is based on . . . carbon. The sixth element in the periodic table. Oh, the other elements are important, all right. Where would we be without hydrogen, or helium, or oxygen? We wouldn't be here having this discussion, I can tell you that! But carbon is special because it is the element that anchors all organic substances, from fossil fuels to DNA. About 24 percent of your body is made up of carbon. So carbon is more than just cheap pencil lead. Carbon makes all life possible. Now you know the basics. We'll continue this talk tomorrow.

Tuesday

We're having a little talk this week about life. One big part of life you may not think much about is carbon. That's right, carbon - the sixth element in the periodic table. When chemistry first became a science, lots of chemical compounds were obtained from plants and animals. Since these substances were derived from living things, or things that used to be alive, the study became known as organic chemistry. Birds, bees, you and me - we are all composed mostly of organic compounds. Oil is an organic compound, too, because it is made of decomposed plant life. That's why we call it a fossil fuel. Plastics, rubber, paper and wood are all organic substances, too. Anyway, chemists realized that organic compounds all had something in common - they all had carbon atoms.

Wednesday

In an old episode of Star Trek, Captain Kirk and his intrepid crew stumble across a mining operation where solid, round nodes are being dug up. The miners think these things are inert lumps of silicon but - and this seems to happen a lot in science fiction - they turn out to be the eggs of a very displeased creature. Why am I telling you this? Because the Enterprise crew was surprised to find a life form that appeared to be silicon-based. See, we refer to all life forms here on earth as "carbon-based." Carbon is important because it has the unique ability to form four separate bonds with other atoms. That means a carbon atom can share four of its six electrons with other atoms. Oxygen can make only two bonds and hydrogen only one. So carbon is a bonding champ.

Thursday

In their book The Way Life Works, Mahlon Hoagland and Bert Dodson illustrate how carbon atoms are so good at forming bonds with other atoms. They explain it by using a plumbing analogy. Let's say you have a straight, ordinary length of pipe. It has only two connections, right? The only way you can lengthen it is by adding more pipe to one or both ends. Now think of a pipe that's shaped like a lug wrench, with four ends sticking up north, south, east and west. This is a versatile pipe, because you can extend it in more directions, maybe with joints for additional fittings. Carbon atoms play a similar role in life. They enable long-chain molecules to form, adding length and connections for side groupings. The variety of life has a lot to do with carbon.

Friday

Scientists call the chemistry of carbon the chemistry of life. Sometimes it's called "organic chemistry." Plants and animals are made up of mostly organic compounds. So is most of the food we eat, which is derived from living things. But carbon is a common compound in many non-living things as well. Graphite, a mineral so soft it is used for pencil lead, is made of carbon. The hardest known natural substance in the universe is diamond. Guess what? Diamonds are made of carbon, too. The carbon atoms are just arranged very differently in the two substances - atoms in diamond are tightly locked together in strong pyramid formations. With six neutrons and six protons, carbon has an atomic mass, or weight, of 12. When scientists compare the relative atomic mass of elements, they use good old carbon as the standard.