What is an Allotrope?

Crystals of the same substance can have many different forms called allotropes. For example, carbon has many different allotropes. These three substances right here are all made up of carbon, just in different forms or allotropes. The first is diamonds.

This is when atoms are covalently bonded to four atoms. You have this one carbon atom that’s covalently bonded to four neighboring carbon atoms. That makes diamonds. That makes a very rigid and hard structure, which is actually the hardest substance on earth.

Then there’s also graphite, which is what pencil lead is made out of. This is when the atoms arrange in hexagons in sheets. These atoms are arranged in hexagons and these hexagons are arranged in sheets that can slide back and forth on each other. This makes something that’s very soft.

That’s why it’s used for graphite. There’s this newly discovered substance that is made up of 60 atoms arranged in a hollow sphere, almost like a soccer ball. These are all made up of carbon atoms. I didn’t write it in all the descriptions here, but those are the atoms we’re dealing with here.

These are carbon atoms that are covalently bonded to four neighboring carbon atoms. Graphite is when carbon atoms are arranged in hexagons that are arranged in sheets. This new substance is 60 carbon atoms arranged in a hollow sphere. This is all made up of carbon, but we have three different substances. That’s because of allotropes. That’s when crystals of the same substance can have different forms.