ARE ATOMS THE SMALLEST PARTICLES OF MATTER?

The word “atom” comes from an ancient Greek word for a tiny piece of matter too small to be split up. Today we know that even atoms are made up of smaller parts, called subatomic particles. Protons and neutrons are the particles that make up the nucleus of an atom, while electrons can be thought of as circling around the nucleus like orbiting planets. However, these are not the only subatomic particles. Scientists have found hundreds more and are still discovering others by using a machine called a particle accelerator. Quarks, for example, form part of neutrons and protons.

When physicists first collided electrons with protons, they observed that electrons bounced off three small hard cores inside the proton. The cores were then called quarks and it was found to be even smaller particles that make up the proton. Quarks are the smallest particles we have come across in our scientific endeavor. Discovery of quarks meant that protons and neutrons weren’t fundamental anymore.

For more thorough understanding let’s peel apart a piece of matter and discover its constituents by removing each layer one by one. From a bird’s-eye view, matter looks rigid and its properties easily measurable. But even a 6-year-old can deduce that the tenacious pillars of his carefully engineered sandcastle are the sum of billions of microscopic sand grains. What constitutes the sand grain?

Peel another layer and you’ll find a neatly organized structure of atoms. The concept of atoms was first proposed by the Greeks, who believed that objects could be indefinitely split into halves until you were left with a single, indivisible speck of matter. This unimaginably small unit could not be divided further and was, therefore, called an “atom”, derived from the Greek word A-tomos. A for “no” and tomos for “cuttable” or splittable.

 Surprisingly, the theory didn’t fare well. Most of the texts written about elementary constituents were lost and retrieved after multiple centuries. It took almost two millennia for the atom to be was recognized as a real fundamental physical object.

The speculation was finally confirmed in the 1800s when chemist John Dalton conducted a series of ingenious experiments on gases. The average diameter of an atom measured around 50 nano-centimeters – a millionth of a grain of sand. The atom was then the smallest thing known to man.