Soon after the discovery of the neutron in 1932, the Russian physicist Dmitry Dmitrievich Ivanenko (1904-1994) and the German physicist Werner Heisenberg (1901-1976) independently proposed a proton-neutron model of the atomic nucleus. According to this model, the nucleus of an atom of any chemical element consists of protopes and neutrons.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.