ATOMIC THEORY TIMELINE

DEMOCRITUS

• Leucippus came up with Atomic Theory
• Democritus adopted it
• Universe is composed of two elements

Antoine Lavoisier

• Came up with the Law of Conservation of Mass
• Began the conversation of an atom

Law of Conservation of Mass

• States that matter can be changed from one form into another, mixtures can be separated or made, and pure substances can be decomposed, but the total amount of mass remains constant

JOHN DALTON

• Went deeper with tiny particle theory
• Experimented with the particles

DALTON'S ATOMIC THEORY

• Elements consisted tiny particles called atoms

DIMITRI MENDELEEV

• Arranged elements into 7 groups with similar properties
• Made the Periodic Law

J. J. THOMSON

• Discovered the electron
• Found that atoms are made up of tiny particles
• Cathode ray tube

Plum Pudding Atomic Model

• Made to show that the atom has electrons that are scattered like in a pudding
• Proposed by J. J. Thomson
• Made to show that the atom has electrons that are scattered like in a pudding

Robert Millikan

• Measured the charge of a single atom
• Known as elementary charge

ERNEST RUTHERFORD

• Named radiations from uranium and thorium alpha and beta

RUTHERFORD MODEL

• A relatively high central charge concentrated into a very small volume in comparison to the rest of the atom

Gold Foil Experiment

• High central charge was concentrated into a very small volume in comparison to the rest of the atom

Henry Mosely

• Developed the application of X-ray spectra to study atomic structure
• More accurate peroidic table

Niels Bohr

• Showed that atoms have electrons orbit it
• Atomic theory that underlies the periodic table

Bohr Planetary Model

• Atoms orbit but they're quantized

Quantum Mechanical Model

• More complex and mathematical explaining of the Bohr Planetary Model
• ses complex shapes of orbitals

Erwin Schrodinger

• Told how electrons move in wave form
• Described how the quantum state of a system changes with time

Electron Cloud Model

• Developed by Schrodinger and Heisenberg
• Describes where electrons are when they go around the nucleus of an atom

James Chadwick

• Discovered the neutron component of the atomic nucleus