Chemical reactions occur all around us, from the lighting of a stovetop to the cooking of food or from the growth of plants to their decay. However, these reactions often go unnoticed.
As a branch of science, chemistry tries to understand such transformations of matter by delving deep into its composition, properties, and interactions with other substances. And therefore, such chemical reactions and the factors that influence them play a crucial role in chemistry.
Chemistry unravels such bigger and smaller changes by breaking them into macroscopic, microscopic, and symbolic domains.
The macroscopic domain includes everything that can be sensed with human sight or touch. Such changes can be observed or measured- for example, an apple's rotting or freezing water at 0 oC.
As the name suggests, the microscopic domain of chemistry is minuscule and may not be visible to the human eye. It includes atoms, molecules, ions, electrons, protons, neutrons, and chemical bonds that are too small to be seen even with standard microscopes and often must be pictured in mind. For example, it visualizes solid ice as composed of many bonds holding tiny water molecules.
When both the macroscopic and microscopic concepts are expressed in the language of symbols, it leads to the symbolic domain that includes chemical symbols of different elements found in the periodic table, chemical formulas, chemical equations, arrows, graphs, drawings, and various calculations. The symbols also become a language of expression connecting the behaviour of the macroscopic domain with the components of the microscopic domain.
Let’s understand this concept further using a real-life example.
Elements of a Chemical Reactions - Role of Organic Chemistry
The volcano science experiment is the most common chemical reaction we might have once tried as budding young scientists.
The experiment involved mixing baking soda and vinegar with food coloring to watch the volcano erupt. The eruption was the macroscopic change due to the reaction of the microscopic components- NaHCO3 (baking soda) and CH3COOH (vinegar).
The symbolic representation of the complete reaction is-
The substances on the left transformed into those on the right. Such starting materials that undergo chemical changes are called reactants, while the resulting substances are known as products.
This is one way to explain the macroscopic change of eruption and gas evolution using symbolic representations in chemistry.
However, organic chemistry goes beyond and tries to understand change at the microscopic level, which involves breaking and forming chemical bonds and identifies the electrons as the key to reactivity.
Redefining the reaction even more, gives the following picture-
Things get a little tricky here with arrows, dots, positive and negative charges, etc. Some bonds are broken, while some are made.
An organic chemist tries to interpret such transformations at the microscopic level by understanding the nature of the participating atoms, the electrons involved and uninvolved ((valence or lone pair), the reaction conditions (whether reaction is done at room temperature, solvent used, pH, pressure, etc.), the leaving groups, and the nature of the by-product (acidic, basic, or salt, or whether the product obtained is gas, liquid, or a solid residue in nature).
They further redefine and reorganize the substrates into electron-rich (nucleophile) and electron-deficient (electrophile) components to understand the flow of the electrons, the major component driving any chemical reactions.
The whole chemistry is decoded to reveal the straight, curved, upward, and other cryptic arrows. Reactions are segregated into various types- addition, elimination, substitution, rearrangement, and decomposition. Any intermediates (carbocations, carbanions, free radicals) involved are also isolated and studied. The journey continues until the discovery of the unknown and the future of the known is found and expressed.
So, from observing the changes to understanding the elements responsible for them and representing them, chemistry has surely come a long way.
It's not an exaggeration to say that chemical reactions from the very foundation of organic chemistry, driving a multitude of transformations.
In our upcoming chapters focusing on organic chemistry study, we aim to identify and express the transformation continually happening around us by studying all the fundamentals of an organic reaction.
Let’s reveal the cast members and learn their various jargon to entirely understand their world and ours!
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