* The Graphite: The "lead" in a pencil is actually graphite, a form of carbon. Graphite is very stable and doesn't easily react with other substances.

* The Wood: The wood of the pencil is made of cellulose, which is also relatively stable.

What Happens When You Write:

* Physical Change: When you write with a pencil, you're primarily creating a physical change. The graphite flakes off and leaves a mark on the paper. This is a change in the physical appearance of the graphite, not its chemical composition.

Possible "Chemical Changes" (But Not Really):

* Oxidation: Over time, the graphite in a pencil can oxidize slightly in the air. This means it reacts with oxygen to form a thin layer of carbon dioxide. However, this is a very slow process and doesn't significantly change the pencil's composition.

* Burning: If you burn a pencil, that's a chemical change, but it's not something you'd normally do to a pencil! Burning involves reacting the wood and graphite with oxygen, producing ash and gases.

In short, the act of writing with a pencil is primarily a physical change, not a chemical one.