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Hi, my name is Jimmy Neutron. What comes to mind when you hear the word “Neutron”? If you have ever had young children, you may think that this term refers to a member of my family, or maybe me, the animated “Boy Genius” introduced to viewers on Nickelodeon in 2002. Besides thinking of me, most scientists would tell you that a “neutron,” similar to its well known brother the “proton,” is a subatomic particle found in the nucleus of all atoms and isotopes beyond protium, the isotope of hydrogen with no neutrons whatsoever. Unlike the proton, however, a neutron carries no ‘net’ electric charge and has a mass slightly larger than that of a proton. According to WolframAlpha, the mass of a neutron ≈ 1.001378 proton masses [12]. Speculated as to its possible existence as early as 1920 by Ernest Rutherford, its discovery in 1932 by English physicist, James Chadwick, signaled the beginning of the era of the common model for atomic structure and the basis of the picture of particle physics that remains valid today.
I don't know if you knew this, but my name full name, James Isaac Neutron, is actually a combination of Sir Isaac Newton, the father of classical physics, and physicist Sir James Chadwick, who was nicknamed "Jimmy Neutron" after his discovery of the neutron in 1932.
So why do these neutrons matter anyways? For if Chadwick had never discovered the neutron, we would not have stunning pictures like this: two neutron stars colliding and giving off gamma-ray bursts.
Before we delve into the world of the wonderful neutron, let us first review some basic information about the atom:
The smallest particle from which matter is created was named “atom,” meaning that which cannot be divided, by the Greek philosopher Democritus about 2500 years ago [3]. Thus, while we all now know that matter can be further subdivided, the atom remains the smallest structure that an element or material can be divided without changing its characteristics. It is composed of a dense, central nucleus surrounded by shells of negatively charged electrons bound to the nucleus by an electromagnetic force. The atomic nuclei of all elements and isotopes after protium contain a mix of positively charged protons and electrically neutral neutrons. Atoms are classified according to the number of protons and neutrons in its nucleus: the number of protons specifies the chemical element, and the number of neutrons specifies the isotope of the element.
In order to describe to you the process by which Rutherford and Chadwick came across the neutron, I have created three glogsters and a prezi to help explain some general areas regarding their work and, hopefully, give you a greater understanding of the role and discovery of the wonderful neutron!!! To view the Glogs and the prezi simply click on the four links below:
Glog on Biographical Information of James Chadwick
Glog on the Predecessors of the Discovery of the Neutron
Prezi on Chadwick's Main Experiment
Glog on the Significant Effects of the Discovery of the Neutron
For those history lovers out there, here is a primary source for your enjoyment. It is the letter that Chadwick wrote to Nature about his discovery of the neutron: Chadwick's Letter to Nature
And just for fun, here is a picture of James Chadwick created with words used throughout my description of the discovery of the neutron. (This image was created with the web tool "tagxedo" at www.tagxedo.com.)
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