When writing with a pencil, how does the lead that is being laid out on the paper not fall off the page and stick?
In: Chemistry
The material in your pencil is called Graphite. Graphite is arranged in many many super thing layers, and is very smooth.
Paper is super rough on a small scale, lots of tiny bumps.
When you write you are dragging the pencil, and these tiny smootj layers of graphite lay themselves onto the paper. And since the paper is so rough, the smooth graphite layers “get stuck” on the paper.
Think of it like dropping a something into the corner of your room where all your cables are. when you reach in to pull the thing you dropped out, your hand will “get stuck” in the cables.
On molecular level, paper has a lot more ‘roughness’ to it than one might think by simply touching it. When you write with a pencil, the graphite that makes up the lead gets trapped in the gaps which create this molecular roughness hence leaving behind ‘markings’.
Edit: You can observe the ‘inverse’ scenario when trying to write with a pencil on a plastic bag or a very smooth sheet of metal. In those cases the surface you are trying to write on is not rough enough to grab onto the lead and get it to stick.
The lead rubs it self over because Technically its not lead the metal. but graphite. Or carbon. or burned wood. Its stack of layerd carbon which can easily slid off and stick to the surface.
You can do a experiment, draw a tiny circle, then keep drawing in the circle, past a certain point, the lead just simply builds up as power, and when you lift the paper, the lead powder falls off.
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