Answer:Our ideas about atoms have changed a lot!At first, people thought atoms were just tiny, solid balls. Then, we learned they have smaller parts, like electrons floating in a positive "soup" (plum pudding model). Later, we found out there's a tiny, dense center called a nucleus (Rutherford model) with electrons orbiting it like planets (Bohr model). Now, we know electrons are in more complex "clouds" of probability around the nucleus (quantum model).So, atoms went from simple balls to complex structures with even stranger, wavelike electrons!