Why can we break graphite when it is made of graphene which is like 40 times more harder than diamond?(according to google)
In: Chemistry
Graphene is essentially a 1-atom-thick “sheet” of carbon. The bonds between the carbon atoms in this sheet are stronger than the bonds between carbon atoms in diamond. However, graphene is a two-dimensional material, while diamond is three-dimensional. So, while graphite *is* made of graphene, it is really made of multiple sheets of graphene that don’t stick to each other very well, which makes it easy for us to pull one sheet away from another and break graphite.
The thing with “hardness” is that it doesn’t actually say anything about how strong the material is. Hardness is a measurement of a material’s resistance to scratches. Harder materials are sought after for things like smart phone screens and luxury watches because it means they will stay scratch-free for longer. And its for this same reason that diamonds are preferred for rings, because it ensures their shine does not dull over time.
But believe it or not, diamonds are actually very brittle. You can easily smash a diamond to a million pieces with a metal hammer and not much force.
Graphite is a bit like a loose pile of papers. If you split a pile of that then you are not ripping apart the individual papers, you are just moving some papers to one side and others to the other side which is much easier. The individual papers here are the graphene-like sheets in graphite.
The hardness of graphene and diamond isn’t easy to compare as one is a thin sheet while the other one is a three-dimensional crystal.
Hardness is pretty useless. Glass is as hard as steel, but it isn’t too hard to break, right? You can crush diamond fairly easily too.
Graphite is a bunch of tiny sheets of graphene pressed together. Graphene is only ever sheets. They’re not held together very firmly at all. It’s the difference between a block of wood and a pile of paper shreddings.
Since no one has added it, pencil graphite isn’t straight carbon. It [has clay mixed in](https://pencils.com/pages/hb-graphite-grading-scale) to soften it. That’s why you have No. 2 pencils.
But the main reason has to do with shear strength vs compressive strength and their relationship with hardness.
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