The Colour Changing Magic of Chemical Reactions
Written By: Hayagreev Kommu
From campfires to the rusting of your dad’s favorite toolbox, chemical reactions are everywhere. One wonders – what is happening in there? The same question has haunted many of the legends in the fields of chemistry. Only after their discovery of how atoms are structured and interact with each other can we understand how chemical reactions occur. So, let’s start with that!
Atomic Models
Ancient Greek philosophers had already coined the word ‘atmos’ hundreds of years before Dalton put forward his theory of these tiny indestructible particles. But J.J. Thompson was the one to propose what resided in the atoms a positive cloud of with negatively charged particles embedded in the cloud (this model earned the name “Plum Pudding Model” due to its resemblance to Plum Pudding). Later, Ernest Rutherford disproved Thompson with his own model which was quite similar. This model was accepted by the scientific community till Niels Bohr, a young scientist, turned the tables by finding flaws in Rutherford’s model and pushing his own modern Atomic Theory forward – the atomic structure which is in our textbooks today. This model has a nucleus which consists of protons-positively charged particles and neutrons-negatively charged particles. This nucleus was orbited by shells of electrons which were to have 8 electrons in the last shell to be stable. Anything more would be sent to the next shell and react with other atoms. Anything less would also cause it to react with other atoms.
Ionic Bonding:
When the external shell has 1-3 electrons, it prefers to lose them. These are called metals. When the external shell has 5-7 electrons it gains electrons from atoms which prefer to lose them. These elements are called non-metals. When a metal and a non-metal come into contact, they exchange electrons and get electrically charged. Though their external shells have the optimum no. of electrons now, they have a charge as they have more electrons than protons (which causes a negative charge) or more protons than electrons (which causes a positive charge). Since the atoms have charges which are opposite to each other now (atoms with charges are called ions), they are attracted to each other and form a bond called an ionic bond.
Covalent Bonding:
When 2 non-metals meet each other, theyshareelectrons. For example, element 1 has 7 electrons in its outer shell. So does element 2. The outer shells join to share 1 electron of each. So, element 1’s shell is full as Element 2 is sharing an electron. So is Element 2. This bond is called a covalent bond.
