Kashyap was on a pilgrimage to Prayag when he saw thousands of pilgrims litter the streets with flowers and rice grains, which they offered at the temple. Kashyap, fascinated by small particles, began collecting the grains of rice. A crowd gathered around to see the strange man collecting grains from the street. Kashyap was asked why he was collecting the grains that even a beggar wouldn’t touch.
He told them that individual grains in themselves may seem worthless, but a collection of some hundred grains make up a person's meal, the collection many meals would feed an entire family and ultimately the entire mankind was made of many families, thus even a single grain of rice was as important as all the valuable riches in this world.
It was around 440 B.C, Democritus first proposed that everything in the world was made of tiny particles surrounded by empty space. He even speculated that they vary in size and shape depending on the substance they compose. He called these particles ‘atomos’ the Greek word for indivisible.
Sadly, his ideas were opposed by the most popular philosophers of his day. Aristotle, for instance,disagreed completely, stating instead that matter was made of four elements:earth, wind, water and fire.
DIFFERENCE BETWEEN BOHR'S MODEL OF ATOM &QUANTUM MECHANICAL MODEL