What Is Chemistry?

Look at your hand. Now look at the air, a glass of water, a slice of bread, a star in the night sky. They seem completely different — but zoom in far enough and they're all built from the same kind of tiny building block: the atom.

There are only about 90 naturally occurring kinds of atoms, yet they combine in endless ways to make every single thing in the universe. The whole world is like a LEGO set with fewer than a hundred kinds of bricks.