Whose discovery first identified the proton as a fundamental particle in the nucleus?

Rutherford’s later experiments on nuclear reactions revealed that a hydrogen nucleus was being emitted from nitrogen when it was bombarded with alpha particles. By 1919, he had identified the hydrogen nucleus as a fundamental constituent of atoms and eventually named it the proton. This was a major step in understanding atomic number and nuclear chemistry. It also helped explain why hydrogen is the simplest and lightest element. Rutherford’s work tied atomic structure to the periodic table’s underlying order.