First, Tom Musun discovered electrons, and then put forward the conjecture of "jujube cake model", that is, negatively charged and positively charged substances containing electrons in atoms are evenly distributed in atoms, just like jujube cakes (electrons are like dates, and positively charged substances are like flour).

Rutherford rejected the "jujube cake model" and put forward a "nuclear model" after gold foil was bombarded with alpha particles (helium nuclei), that is, electrons were outside the nucleus and positive charges were inside the nucleus, and then protons and neutrons were found, which improved the nuclear model.

Bohr discovered the orbital motion (energy level) of electrons,

In the 1960 s, American physicist Murray? Gherman and G Zweig independently proposed that hadrons such as neutrons and protons are composed of quarks, and quarks are the more basic units.