Inside the Atom: Mostly Empty Space

Atoms make up everything. But people once thought atoms were indivisible. That idea died fast.

In 1897, J.J. Thomson ran electricity through gas. The gas lit up.

If atoms were solid… where did the light come from? Turns out… something negative

was being ripped out of atoms. Those were electrons. Atoms are not indivisible. Thomson thought

atoms looked like this. Positive charge everywhere… Electrons floating

inside. This was called the plum pudding model. Then Rutherford

said: “Let’s test that.” He fired alpha particles at thin gold foil. Most passed straight

through. But some… bounced back. That made no sense. If atoms were pudding,