Atom models:

Atom models:

1. Democritus (around 460 BCE)

   • The first idea of the atom came from a Greek philosopher named Democritus. He said that all matter is made of tiny, solid particles called atoms. These atoms cannot be divided or destroyed, and they move through empty space. Democritus believed that atoms have different shapes and sizes depending on the material.

2. Dalton (1808)

   • This model was made by John Dalton. He said that atom models are solid, round balls like tiny marbles. According to Dalton, atoms cannot be broken into small parts, and all atoms of the same element are exactly the same.

3. Thomson (1897)

   • Later, J.J. Thomson discovered the electron, a tiny negative particle inside the atom. He said the atom was a ball of positive charge with negative electrons stuck in it, like raisins in a pudding. This was called the "plum pudding" model.

4. Rutherford (1911)

   • Then, Ernest Rutherford did an experiment with gold foil. He found that most of the atom is empty space, but there is a small, heavy, positive center called the nucleus. Electrons move around this nucleus, like planets around the sun. This model was a big change from Thomson’s idea.

5. Bohr (1913)

   • Next, Niels Bohr improved the model. He said that electrons move in fixed orbits (also called energy levels) around the nucleus. Electrons can jump to higher or lower orbits when they gain or lose energy. This model helped explain why atoms give off light in certain colors.

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