enrico fermi discovered protons and neutrons in the nucleus.
who discovered protons and neutrons in the nucleus?
enrico fermi
the atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by ernest rutherford based on the 1909 geiger–marsden gold foil experiment. after the discovery of the neutron in 1932, models for a nucleus composed of protons and neutrons were quickly developed by dmitri ivanenko and werner heisenberg. an atom is composed of a positively-charged nucleus, with a cloud of negatively-charged electrons surrounding it, bound together by electrostatic force. almost all of the mass of an atom is located in the nucleus, with a very small contribution from the electron cloud. protons and neutrons are bound together to form a nucleus by the nuclear force.
atomic nucleus
atomic nuclei consist of protons and neutrons bound together by the residual strong force. because protons are positively charged, they repel each other. neutrons, which are electrically neutral, stabilize the nucleus in two ways. their copresence pushes protons slightly apart, reducing the electrostatic repulsion between the protons, and they exert the attractive nuclear force on each other and on protons. for this reason, one or more neutrons are necessary for two or more protons to bind into a nucleus. as the number of protons increases, so does the ratio of neutrons to protons necessary to ensure a stable nucleus (see graph at right). for example, although the neutron:proton ratio of is 1:2, the neutron:proton ratio of is greater than 3:2. a number of lighter elements have stable nuclides with the ratio 1:1 ("z" = "n"). the nuclide (calcium-40) is observationally the heaviest stable nuclide with the same number of neutrons and protons; (theoretically, the heaviest stable one is sulfur-32). all stable nuclides heavier than calcium-40 contain more neutrons than protons.
isotope