1 Jan 1932 Jahr - Chadwick

Beschreibung:

In 1932, Chadwick discovered the neutron, a subatomic particle with no charge that constitutes the nucleus of an atom, along with the proton (Famous Scientists, 2014). Before this discovery, it had been suspected, but known proven, that there was some other subatomic particle with no charge present in the nucleus; Rutherford, Chadwick and others had been searching for years for a way to detect the neutron (ABCTE, 2007).

Chadwick's discovery was made by firing alpha particles, helium nuclei, at beryllium atoms (ABCTE, 2007). This resulted in the release of an unknown type of radiation from the beryllium, initially believed to be gamma radiation (Nave, n.d.). However, when paraffin wax was exposed to this radiation, protons were knocked out, and Chadwick considered it improbable that photons of electromagnetic radiation could knock loose such heavy particles as the proton (APS Physics, 2007). This led him to suspect the radiation from the beryllium was actually the uncharged particles he had been searching for: the neutron (APS Physics, 2007). With further experiments, he calculated that the mass of the neutron was slightly heavier than the proton (ABCTE, 2007).

The discovery of the neutron was crucial to the Manhattan Project, which Chadwick supported, in World War II. As neutrons are uncharged, unlike protons, they are not repelled by the electrostatic forces of the nucleus and can thus penetrate deeper into it (Famous Scientists, 2014). This enabled the nuclear fission of uranium, which releases enormous amounts of energy (Famous Scientists, 2014).

Thus. Chadwick unveiled another subatomic particle and thereby made a crucial addition to the atomic model.

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