Now that we’ve discussed the structure of the atom in depth and some of the scientists and the scientific experiments involved in the discovery of the atom’s structure, we will move on to a discussion about nuclear structure and isotopes. Some of the concepts that I will review will seem familiar, but they are pertinent to the topic, so they will be reiterated.
While we know now with certainty that the atom itself has a structure, we also know that the nucleus of the atom has its own individual structure. The nucleus of an atom is comprised of protons and neutrons, both of which were mentioned before. What’s more, the experiment that I mentioned where the alpha particle-scattering occurred was also important to the discovery of the nucleus’s structure (Ebbing and Gammon 2009).
Because of the importance of the electric charge of a nucleus, scientists have devised methods to determining the value of the positive charge of a nucleus. This can be done by analyzing the distribution of alpha particles scattered from a metal foil, or even analyzing the x rays emitted by an element when it is irradiated with cathode rays, which is a more complex concept that I haven’t reviewed yet. Using experiments like these, researchers over time have discovered something to be true of each element. For each element, a unique and distinct nuclear charge exists, which happens to be an integer multiple of the magnitude of the electron charge. This integer has been dubbed as Z, and it is known as an element’s atomic number. The atomic number of an element is a characteristic of that element. The hydrogen atom has the smallest atomic number at a value of 1, and its magnitude of charge is equal to that of the electron (Ebbing and Gammon 2009).
Although I mentioned what a proton is before, it is helpful to go over it again. A proton is a nuclear particle that is positively-charged and has a mass that is more than 1,800 times greater than that of the electron. Sometimes, a proton is knocked out of the nucleus when an alpha particle collides with an atom, which may happen, for instance, with a nitrogen atom. So, the number of protons that exist within the nucleus give it its characteristic positive charge (Ebbing and Gammon 2009).
Thus, Z, or the atomic number as I mentioned it to be, is defined as the number of protons that exist in the nucleus of an atom. Because an element’s atomic number is characteristic of that element, and the atomic number of an element can be determined through scientific experiment, it is now relatively easy to determine whether a sample of an element you have is impure or if it is an altogether new element. Knowing this new characteristic of an element, it is now easier to say what an element really is: it is a substance whose atoms all have the same atomic number (Ebbing and Gammon 2009).
In this post, you have learned about the atomic number. In the next post, I will review what the mass number is and I will do a brief review of some of the essential information we’ve learned about protons, electrons, and what we will learn about neutrons.
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