What kinds of carbon are there?

Discover how this protean wonder-element can make more than 9 million different chemical compounds

(Image source: Pixabay)

Carbon is so versatile and so important that the Royal Society of Chemistry call it the ‘King of the elements’. It’s everywhere, and we use it for everything. Carbon sits at position six on the periodic table. It has six protons, six neutrons and six electrons. Two of those electrons fill up an electron shell close to the nucleus, while the other four sit in a half empty shell around the outside. These outer electrons, known as the valence electrons, are the key to carbon’s incredible properties.

The electrons in an atom’s outer shell are the ones that take part in chemical bonds. How many bonds depends on how much room there is in the shell, and the amazing thing about carbon is that it’s got space for four. This means that it acts like a plumbing cross-piece, becoming a four-way connector that links different atoms together. It can build straight chains, chains with branches, and chains joined end to end to make loops.

And it doesn’t just bond to itself. The edges of carbon chains can terminate in tiny hydrogen atoms, making them slippery like oils. Or they can connect to other groups of elements, called ‘functional groups’, each of which has different chemical properties. Carbon works like elemental scaffolding, and the shapes, sizes and chemistry of the molecules it creates vary enormously.

Carbon allotropes

Diamond: Prehistoric

The carbons in a diamond form four bonds each, making tetrahedrons that link together to make 3D rings of six atoms.

Graphite: Prehistoric

Graphite contains slippery layers of carbon atoms arranged in flat sheets of hexagons. Electrons move freely between them.

Buckminsterfullerene: 1985

The original buckyball has 60 carbon atoms and is round in shape. They slip past each other and melt easily.

Nanotube: 1991

These hollow cylinders look like rolled up graphene sheets. They resist stretching and conduct electricity.

Graphene: 2004

As the world’s thinnest material it is 1 million times thinner than the diameter of a human hair. It is strong, lightweight and flexible – properties that make it useful in a range of industries.

(Illustrations: Future PLC)


 This article was originally published in How It Works issue 130, written by Laura Mears 


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