Abstract
Today we have an idea of what makes up an atom. The model of an atom has two main parts: the core (usually called the atomic nucleus), where most of the atomic mass is located, and a cloud of electrons surrounding it. The electrons move on orbits around the nucleus. These permitted orbits are also called electron shells and are named alphabetically with capital letters, starting with K. The atomic nuclei are made up of an integral number of protons and neutrons. While the protons carry a positive charge, the neutrons are electrically neutral. Electrons and protons carry the same charge, but of opposite sign. This charge is called the elementary charge, e: e=1.602×10−19 C. Since the number of negatively charged electrons is equal to the number of protons in the nucleus, the atom itself is electrically neutral.
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Wolf, U., Wiezorek, T. (2008). Radiophysical Principles. In: Seegenschmiedt, M.H., Makoski, HB., Trott, KR., Brady, L.W. (eds) Radiotherapy for Non-Malignant Disorders. Medical Radiology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-68943-0_4
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DOI: https://doi.org/10.1007/978-3-540-68943-0_4
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