if atoms are too small to see, how do we know atoms exist? And who discovered atoms?

Question

This was a real question by my 6yo. She asked what was made of atoms. I said everything, but they’re too small to see. “Oh, microscopic!” “Well, smaller actually.” “How do people know they exist? And what’s the name of the person who discovered them?”

Marked as chemistry cause that’s how ill-equipped I am to answer this question. Is it chemistry? Or should I have said physics?

In: 4

Answer 1

We can’t see them directly but we have models that predict their behavior and we have experiments to test the model.

It’s like if I was in a pitch black room and I throw a basketball at the wall. I can’t see the wall but I’d expect the ball to bounce back if there is a wall.

No idea who discovered atoms though.