What part of Dalton's theory of was disproved when scientists discovered that atoms contain protons electrons and neutrons?

John Dalton believed that atoms were the fundamental building blocks of matter, and that they could not be created, destroyed or split. However he was wrong, because atoms are made out of subatomic particles such as Protons, Neutrons and Electrons - and later still, it was discovered Protons and Neutrons too are made of even smaller particles.