6 fev 1932 ano - Sir James Chadwick
Descrição:
Summary: Chadwick discovered the neutron, resulting in the atomic model we still have today.
How did he find this out?:
Experiments by Hans Geiger and Ernest Marsden, partners of Ernest Rutherford, found that the protons in an atom could not account for more than half of its mass. This meant that some neutron must be present in the nucleus or otherwise the charges would not be balanced.
However, as we now know, Chadwick did exactly this. By bombarding beryllium with alpha particles, a stream of rays was shot out. However, these were initially thought to be gamma rays as, like gamma rays, these particles were extremely penetrating and were not disturbed by a magnetic field and therefore were neutral. Despite this, they did not produce ... so they were found to be neutrons.
How did this change the atomic model?
This accounted for the difference between the atomic number and the atomic mass and explained what took up the rest of the space in the nucleus.
References:
-PhysicsLAB: Famous Experiments: The Discovery of the Neutron. (2018). Dev.physicslab.org. Retrieved 12 February 2018, from http://dev.physicslab.org/Document.aspx?doctype=3&filename=AtomicNuclear_ChadwickNeutron.xml
Pictures:
Top: Portrait
Middle: The Current atomic model.
Bottom: The experiment used by Chadwick.
Adicionado na linha do tempo:
History of the atom
Data:
Imagens:
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