By Angela Huang
A Brief Introduction of Atomic Structure and The Periodic Table
An atom consists of protons, neutrons (except Hydrogen), and electrons. The protons and neutrons are clustered together and are located at the center of the atom, which is collectively called a nucleus. Electrons are moving at high speed around a nucleus, following a certain track called orbital. A proton carries one “+” electric charge and an electron carries one “-” electric charge. Thus, for an atom, the number of protons is always equal to the number of electrons to make the whole atom electrically neutral. Scientists have found that the properties of an atom depend on how many protons it has. An element is defined based on how many protons an atom has. We give the element a name and organize all the elements into a periodic table. In the table, an element is placed based on how many protons the atom has, as shown in the picture below. It is convenient to use as the users can easily figure out useful information based on the position of an atom in the table. For example, one can see the amount of protons and electrons, the arrangement of electrons, the relative reactivity of atoms, and more.
Periodic Table
Motions and Arrangement of Electrons
As discussed, electrons orbit a nucleus while strictly following a certain arrangement. This arrangement includes shells and orbitals, which divide the space outside the nucleus into zones depending on its distance from the nucleus. Electrons always try to occupy a position closest to the center whenever possible. However, each shell and orbital have a limitation on how many electrons they can take, so once the closer position is occupied, the next electron will occupy the next available position. To represent this process visually, let’s employ a bookshelf as an analogy. Putting electrons into their tracks is similar to putting books into a bookshelf: we can do it one by one and from bottom to top. The electron closest to the nucleus has the lowest energy and the electron further away from the center has higher energy. When electrons are arranged in order, the electrons are relatively stable. However, when electrons absorb or lose energy, they will have to move a higher or lower energy position, that is, further or closer to the center respectively. For example, when an electron moves from a higher energy position to a lower energy position, it will release photons that carry the energy loss of electrons. Macroscopically, what we can see is the emission of colored light beams.
Electron Shell
Applications of Electrons and Photons
By intentionally energizing an electron, moving it from a low energy to a high energy position, and allowing it to fall back, we can produce photons and make them useful for us. Fluorescent lamps, neon signs, and sodium-vapor lamps are common examples of this application that uses electrical energy to make the gas emit light of a certain color.
Conclusion
In conclusion, the structure of the atom, with its protons, neutrons, and electrons, forms the foundation of all chemical elements and their properties. The arrangement of electrons is key to not only the stability of the atom but also its chemical behavior and explains much of what we see in the world today. Ultimately, the study of electron dynamics enhances our understanding of the world and opens the door to future innovations and technological advancements.
Sources
Steven S. Zumdahl and Susan A. Zumdahl (2013). Chemistry, 9th edition, Cengage Learning, 1200p.
Theodore E. Brown, H. Eugene LeMay, Bruce E. Bursten, Catherine Murphy, Patrick Woodward, Matthew E. Stoltzfus (2017). Chemistry: The Central Science, 14th edition, Pearson, 1248p.
Dhali, D. (2024, May 9). Electron shell - definition & number of electrons in each shell. Science Facts. https://www.sciencefacts.net/electron-shells.html
U.S. National Library of Medicine. (n.d.). Periodic Table of elements - pubchem. National Center for Biotechnology Information. PubChem Compound Database. https://pubchem.ncbi.nlm.nih.gov/periodic-table/
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