What is the history of atomic theory?

What is the history of atomic theory?

Atomic theory has evolved significantly since ancient times. It began with philosophers like Democritus, who proposed that matter is made up of indivisible particles called 'atoms.' In the early 19th century, John Dalton formalized this idea, introducing the first modern atomic theory.

What were Dalton's main contributions?

Dalton's main contributions included the idea that each element is made of unique atoms, that atoms combine in fixed ratios to form compounds, and that chemical reactions involve the rearrangement of atoms.

How did the theory change after Dalton?

After Dalton, the theory evolved with discoveries like J.J. Thomson's electron in 1897, which introduced the idea of subatomic particles. Then, Ernest Rutherford's gold foil experiment in 1909 revealed the nucleus, leading to the planetary model of the atom.

What is the current understanding of atomic structure?

Today, atomic structure is understood through quantum mechanics, which describes electrons in probabilistic terms rather than fixed orbits. The modern model includes protons and neutrons in the nucleus, with electrons in cloud-like orbitals.