Answer:
James Chadwick
Step-by-step explanation:
Hello,
At first, Ernest Rutherford developed the first approximated model of the atom which was viewed as composed by both protons and electrons, the two tiniest particles known at the time, nevertheless, such model exhibited several both experimental and theoretical inconsistencies.
Afterwards, a more accurate sight of the atom was established with the discovery of the neutron by James Chadwick in 1932 and its subsequent classification as an elementary particle unlike the proton.
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