Atomic Timeline

Atomic TIMELINE

Atomos

400 B.C

Democritus

Billard Ball Model

1803

Dalton

1904

Thomson

Gold Foil Experiment

1911

Rutherford

Planetary Model

1913

Bohr

1926

Schrödinger

Electron Cloud Model

Plum Pudding Moedel

A Greek philosopher Democritus had an idea! All matter can be divided into smaller pieces. He used the word atomos to describe the smallest possible piece of matter.

J. Thomson-The English Scientist who discovered electrons in 1897

• Determined electrons had a negative charge through experiment.
• Atom is made of electrons unevenly distributed within elastic sphere surrounded by a soup of positive charge to balance the charge

Gold Foil Experiment Atom is made of electrons unevenly distributed within elastic sphere surrounded by a soup of positive charge to balance the charge Rutherford Model stated 1. An atom is mostly empty space 2. There is a small positive nucleus 3. Negative electrons scattered around the outside edge

Neil Bohr - The Danish scientist who proposed the Planetary Model of the Atom

• Electrons moved in definite orbits around the nucleus with a specific energy level
• Orbit have a set size and energy
• The energy is related to size
• Radiation is absorbed or emitted when an electron moves from one orbit to another

John Dalton was an English Chemist that was the 1st that proposed Atomic Theory . His theory included: 1. All elements are composed of Indivisible Particles 2. Atoms of the Same Element are exactly alike. 3. Atoms of different elements are different 4. Compounds are formed by joining atoms of 2 or more elements

In Schrödinger's model there is no definite position for electrons around the nucleus. He devleoped mathmatical equations to describe the probability of an electrons location.