The periodic theory owes much of its development and progress to quantum mechanics theory, which can describe the behavior of elements in terms of chemical bonding, the fundamental building block of the periodic table (Tro, Nivaldo J). The quantum mechanics theory aided Niels Bohr in developing his atomic model, which has assisted future scientists in explaining the location and properties of an element in the periodic table (Olmsted, John et al.). The discovery of the theory no emission of moving electron, which is in direct contradiction to the classical theory, has been in the basis of the development of a stable atomic model. Bohr postulated that electrons only emits or radiates when it changes its state by jumping from one state to the another.
Heisenberg’s uncertainty principle and its solution, that are based on the quantum theory, has introduced the orbital function of electron, which in turn has given rise to four quantum numbers: principle quantum number, angular quantum number, magnetic quantum number and the spin quantum number (Eyring, Henry et al.). All these four quantum numbers can precisely predict the position and chemical properties of an element in the periodic table. Again, no two electrons can have all four quantum numbers in common, which explains why only one element is located in a single position in the periodic table and why the elements do not overlap.
With the emergence of large number of element discovery between 1700 and 1800, scientists started to feel the urge to group together based on their chemical properties to get quick idea about their characteristics. The first known attempt was made by a German Scientist named Johann Dobereiner, who simply created a triad, in which he grouped three elements having same properties. Johann Dobereiner, an English Chemist, has escalated the number of elements into eight to make similar to the musical octaves. Russian Chemist, Dimitri Mendeleev is regarded as the father of modern periodic table, who brought the essential changes and development to early techniques of grouping elements together. Mendeleev’s periodic table suggests, if elements are grouped based on their incremental atomic mass, their properties are likely to recur periodically across the rows and columns of the table (Brescia, Frank).
Mendeleev’s periodic table can be seen as the revolutionary discovery for the chemistry because besides describing and explaining the properties of existing elements, it can precisely predict the existence of non-discovered elements, which later found to true. Few difficulties in explaining properties of elements and positioning them into the periodic table has led researcher to further development; in response to the need to mend few problems in the periodic table developed by Mendeleev, Henry Moseley, an English Chemist has proposed an atomic number based periodic table in place of Mendeleev’s atomic mass based periodic table. This periodic table is what we see and use today extensively; it has the potential to provide unique position to each element that ever existed and will be discovered. The electron configuration of elements show that every element has unique electron configuration, which helps it get a unique position in the periodic table. It is the electron configuration that determines the properties, both physical and chemical, of an element, which can be predicted by taking its position into the periodic table. Thus, the quantum theory and its successor, periodic table are two most revolutionary discoveries of the chemistry that never stopped elevating the growth and application of the chemistry to the betterment of human race.
Brescia, Frank. Fundamentals Of Chemistry. 1st ed., Elsevier Science, 2013.
Eyring, Henry et al. Quantum Chemistry. 1st ed., [United States], [Nabu Press], 2011.
Olmsted, John et al. Chemistry. 1st ed., Toronto, Wiley, 2013.
Tro, Nivaldo J. Chemistry. 4th ed., Pearson Education, 2017.