ACCE Chemistry - History of Modern Atomic Theory

People, dates, and brief description

1782

Antonine Lavoisier - Law of Conservation of matter (mass) - matter is neither created nor destroyed, mass of reactants=mass of products

1933

James Chadwick - proved existence of neutrons, explains Isotopes (because of different masses)

1785

Charles Colomb

Law of electrical charge, opposites (= and -) attract, like magnets

1799

Joseph Proust

Law of multiple proportions and law of definition proportions

1926

Erwin Schrodinger - Charge cloud model - nodes (places where electron can’t be) Nucleus is a dense core with protons and neutrons - orbital/electron cloud=area of probability where an electron might be

1803

John Dalton - Dalton Atomic theory - “father of atomic theory” - problem with his blank ball model is that it lacks subatomic particles

1927

Werner Heisenberg - Heisenberg Uncertainty Principle: the more precisely the location of an electron is determined, the less precisely the speed is known - going fast, moving can only know the general area

1924

Lous de Broglie - Found that electrons can sometimes act like waves or particles: wave-particle duality

1839

Michael Faraday - Atomic structure may have electrical charge

Ben Franklin - proton + and electron -

450 BC

Aristotle - matter is continuous, fire-air-water-earth… Problem with model: no evidence

Democritus - World is made of empty space and atoms - atomos=indivisible… Problem with model: no evidence

1897

JJ Thomson - Cathode Ray Tube - reason we don’t believe Rutherford’s model, Cathode Ray Tube proved that atoms have charges Plum-Pudding Model, Problem is that there’s no nucleus

1913

Niels Bohr - Solar System Model: Problem is that it only works for hydrogen, we couldn’t find electrons in the prediction of energy levels

1909

Ernest Rutherford - Gold Foil Experiment - His model was wrong because the law of electrical charges says that + and - attract