Living in an intimate relationship is very difficult for most people but very pleasurable and rewarding. We forget our differences and make an effort to live together sharing the same bed, getting naked in front of each other, doing things we would not have dreamt of doing with others. Both the partners have to realize this and they have to constantly work on it to make it last long. I don’t mean to coax it to happen though.
You know even most of the atoms react and form substances because they want to be together. Take the commonest table salt, written as NaCl. Sodium feels happy when it has 8 electrons in its outermost shell but it has 9. Chlorine feels happy when it has 8, desolé it has only 7. So Sod and Chlo come together and they form a bond in which Sod donates one electron to Chlo and Chlo gracefully accepts it. Sod now sports a + sign on its feather as it has lost an electron and Chlo now has a – sign on its feather. This kind of bond last forever on a give and take relationship.
There is another kind of substance where there bonding is purely through sharing. Take water written as H2O for example. Hydrogen wants to have 2 electrons in its outermost shell but has 1. On the contrary, Oxygen loves to have 8 electrons in its outermost shell but has 6. So they reach a pact that they are going to share the electrons. So the two Hydros bring in 2 electrons and the Oxy brings in 6 electrons. They have to now share so that each Hydro gets content with 2 electrons by sharing an electron from Oxy and Oxy gets 8 electrons by sharing the electrons of two Hydros. Isn’t this marvelous? Nature always has something to teach us. If you are a cynic you might dismiss the whole thing as theoretical and quote instances where Nature acts against Human will. If you are that kind of person I am afraid, we can not communicate as there is a big wall in front of you and I can not penetrate it possibly.
Some atoms are very content with the way they are and they are akin to people who want to be by themselves. Gases like Helium, Neon, Argon, Krypton and Xenon fall under this category. One more thing is that atoms are so good in sharing that they can even leave their wedded partner in exhange for another one. For example:
Sodium Chloride + Silver Nitrate = Sodium Nitrate + Silver Chloride
NaCl + AgNO3 = NaNO3 + AgCl
You will see that Na has now exchanged with NO3, but it doesn’t desert Cl. It makes sure that it too has got a partner. Divorcing isn’t very common in the chemical kingdom.
When atoms share an electron and decide to part, they do it in two ways: In the first one both the atoms, have no remorse and have willingly divorced each other and take the electron with them which they have pledged to share. This is known as homolytic fission. This reaction produces lot of free radicals and is highly reactive. In the second case, the stronger one decides to keep the shared electron of the other participating atom to itself, generating a negative charge on itself and a positive charge on the other one which has bereaved its electron. It is known as heterolytic fission.
Many things exist in nature in pairs. I remember in my school days when my botany teacher promised us with a cup of ice cream over a question ‘why do homologous chromosomes pair in meiosis’. The answer was very simple: Chromosomes always exists in pairs. Oxygen and Nitrogen present in the air always exist as N2 and O2 , meaning, they exist in pairs. Ah, these chemicals; how much we could learn from them…