ATOMIC MODEL THROUGH HISTORY 1. John Dalton’s Model (1803) – Solid Sphere Model Overview: Dalton proposed that all matter is made up of indivisible particles called atoms. He imagined atoms as tiny, solid spheres—like billiard balls. Key Ideas: Atoms of the same element are identical in mass and properties. Atoms cannot be created, divided, or destroyed. Compounds form when atoms of different elements combine in fixed ratios. Importance: First scientific model of the atom based on experimental e