ATOMIC MODELS SCIENCE

reference used: Book

Democritus

• Father of atomism 

• Proposed that matter isn’t infinitely divisible

• The starter of the research in atoms :3

• Atom was a philosophical idea

Dalton's atomic theory

• Full name: John Dalton (1766 - 1844) 

•  First to promote the concept of atom in 1803

• Proposed the idea of masses of atoms in different elements

Atomic theory explained:

1] Elements are minute, discrete atoms (indivisible particles)

2] Atoms with the same elements are identical, but atoms with different elements are different.

3] Compounds = more then 1 type of atom in a fixed ratio of small whole numbers

4] Chemical reactions involve the separation, combination, and rearrangement of atoms. No destruction or creation of atoms.

Limitations and missing details in Dalton's theory.

• Can be further divided or altered through fusion

• Missing smaller subatomic particles: electrons. Protons. neutrons

Thomson's Plum Pudding model.

• Story keypoints: 

• British chemist Sir William Crookes (1832-1919)

• High voltage was introduce in a cathode ray tube containing gas

• The invisible ray traveled down to the tube's negative and positive terminals.

Causes the tube to emit a green glow

J.J Thomson [british physicist] (1856-1940)

• Identified negatively charged particles as electrons while investigating the deflections of cathode rays in electric/magnetic rays

• Using the results, Thomson can infer that the atom is made up of positively charged spheres where electrons are evenly dispersed.

• Thomson describes the atom being similar to plum pudding

Rutherford's nuclear model.

• Gold foil experiment: 

• Result 1: Most alpha particles passed through gold foil; the atom is mostly a empty space

• Result 2: Some of the alpha particles were deflected at different angles because they traveled near a positively charged entity.

• Result 3: Few alpha particles bounce back because they have collided with a massive positively charged entity.

  Conclusion to the gold foil experiment.

• A positively charged center named nucleus