When Was the Atomic Theory Created?


Jane Flores

The atomic theory is one of the most fundamental concepts in modern science. It is the cornerstone of chemistry and physics that explains the behavior of matter.

The atomic theory suggests that everything in the universe, including matter, is made up of tiny particles called atoms. But when was this theory created? Let’s take a deep dive into its history.

The idea of atoms was first introduced by ancient Greek philosophers, including Democritus and Leucippus, in the 5th century BCE. They believed that all matter consisted of indivisible particles called atoms. However, this idea did not have any scientific basis and was purely philosophical.

It wasn’t until the 19th century when John Dalton, an English chemist, formulated a modern atomic theory based on experimental evidence. He proposed that atoms were indivisible and indestructible entities that combined to form compounds in fixed ratios. This theory laid the foundation for modern chemistry.

In 1897, J.J Thomson discovered the electron using cathode ray experiments. This led to a new model of the atom known as the “plum pudding” model, where electrons were embedded in a positively charged sphere like raisins in a pudding.

In 1911, Ernest Rutherford conducted an experiment where he bombarded a thin sheet of gold foil with alpha particles (positively charged particles). To his surprise, some alpha particles bounced back at large angles instead of passing through as he had expected. From this experiment, Rutherford concluded that atoms had a small but massive nucleus at their center with electrons orbiting around it.

This gave rise to a new model known as the “planetary” model where electrons orbited around the nucleus like planets around the sun.

Later on, Niels Bohr proposed another model known as the “Bohr model” which suggested that electrons orbited around the nucleus in fixed energy levels or shells.

Today’s modern atomic theory combines all these models and suggests that atoms are made up of a nucleus consisting of protons and neutrons, with electrons orbiting around the nucleus in shells.

In conclusion, the atomic theory has come a long way since the ancient Greeks first proposed the idea of atoms. With advancements in technology and scientific evidence, our understanding of atoms has evolved over time. From John Dalton’s modern atomic theory to Niels Bohr’s energy level model, we now have a better understanding of the behavior of matter at an atomic level.