Final answer:
James Chadwick was an English physicist who discovered the neutron in 1932, leading to his Nobel Prize in Physics in 1935. His discovery completed the basic understanding of subatomic particles and was pivotal to the development of nuclear physics during the early 20th century.
Step-by-step explanation:
James Chadwick was a renowned English physicist who made a groundbreaking discovery in the realm of subatomic particles. In 1932, Chadwick discovered the neutron, a neutral particle with a mass approximately equal to that of a proton. This discovery was instrumental in advancing the atomic theory and contributed significantly to the development of nuclear physics. For this monumental discovery, he was awarded the Nobel Prize in Physics in 1935. Chadwick's discovery of the neutron took place after the identification of electrons and protons, completing the trio of fundamental subatomic particles known at the time, and it played a crucial role in the understanding of atomic nuclei.
The identification of the neutron was crucial in advancing our understanding of atomic structure, enabling the development of atomic models that correctly accounted for the true mass of atoms and helped explain isotopes. Notably, the discovery of neutrons preceded the development of nuclear energy and the exploitation of nuclear reactions. Chadwick's work fits into the timeline of history during the early 20th century, a period ripe with scientific breakthroughs that would lead to the modern quantum and nuclear age.