The concept of atoms has evolved significantly over time as scientists gathered new experimental evidence and refined their atomic models.

John Dalton was the first to publish a scientific theory about atoms in 1803. He proposed that all matter is composed of tiny particles called atoms. According to Dalton, these atoms were indivisible and indestructible spheres.

Key Findings:

• Most of the alpha particles passed straight through the foil, indicating that atoms are mostly empty space.
• However, a small number of alpha particles were deflected in various directions, suggesting that there is a small, dense, positively charged region at the center of the atom.

Alpha particle scattering experiment

Nuclear Model: Based on this evidence, Rutherford proposed a new atomic model, known as the nuclear model.

• In this model, the mass of the atom is concentrated in a central region called the nucleus.
• The nucleus is positively charged and contains most of the atom's mass.