About the Atom

About the Atom

Rakesh Mohan Hallen

Atomos is a Greek word, which means something that cannot be divided further. The familiar English word ‘atom’ indeed originated from this Greek word. It has been in vogue for at least past two centuries. A very large number of phenomena, which form the backbone of this column, can only be explained using this word. No wonder many of our readers are very curious to have some more details about atoms. Some of their queries are as follows:

What is an atom?

• Atoms are not visible even under the electron microscope, then how do scientists see them?

• Why is every orbit of an atom associated with some amount of energy?

• Do the atoms of a substance have any characteristic of colour?

• From where do electrons and protons get their charge?

• Isn’t the Bohr’s model of atoms adequate for most practical purposes?

Atom is a concept in science just like energy or gravity. It helps us to relate the scientific explanations to a large number of phenomena. Unlike a small dust particle, a virus or a bacteria the atom cannot be seen with our eyes either directly or through an optical microscope. We can at best infer the structure of a crystalline solid to be made up of discrete particles through images we develop from an instrument known as a field ion microscope. At best it is an image painted in the mind of a scientist from the results of constant interplay between experiments and theories through the past several centuries. As the technology developed, newer experiments were devised, the results of some of these experiments threw up new questions, which older theories about the constituents/structure of an atom could not explain. Thus the atom as we “see” it today is a result of many