HISTORY OF ATOMS AND MOLECULES
Ancient Indian and Greek philosophers have always wondered about the unknown and unseen form of matter. The idea of divisibility of matter was considered long back in India, around 500 BC. An Indian philosopher Maharishi Kanad, postulated that if we go on dividing matter (padarth), we shall get smaller and smaller particles. Ultimately, a stage will come when we shall come across the smallest particles beyond which further division will not be possible. He named these particles Parmanu. Another Indian philosopher, pakudha katyayama, elaborated this doctrine and said that these particles normally exist in a combined form which gives us various forms of matter.
Around the same era, ancient Greek philosophers – Democritus and Leucippus suggested that if we go on the dividing matter, a stage will come when particles obtained cannot be divided further. Democritus called these indivisible particles atoms (meaning indivisible). All this was based on philosophical considerations and not much experimental work to validate these ideas could be done till the eighteenth century.
By the end of the eighteenth century, scientists recognized the difference between elements and compounds and naturally became interested in finding out how and why elements combine and what happens when they combine.
Antoine L. Lavoisier laid the foundation of chemical sciences by establishing two important laws of chemical combination.
Source: This topic is taken from NCERT TEXTBOOK