chem historical figures

Democritus 400 BC

Democritus 400 BC

First to consider, cut apple to smallest he could and determined smallest were “atomos”, or uncuttable

Dalton 1803

Theorized atoms of different elements were different masses and are composed of empty space

Thomson 1897

Conducted cathode ray experiment and discovered electrons, made plum pudding model of atom

Planck 1900

Composed quantum theory, states that energy is released in short bursts, not continuous waves

Milkman 1909

Discovered mass and charge of electron using Oil Drip experiment, proved quantum theory

Rutherford 1911

Theorized Rutherford model, with dense positive nucleus, orbiting electrons and empty space, based off of gold foil experiment, shot alpha particles at gold foil, many scattered

Bohr 1913

Applied Rutherford model and quantum theory, discovered energy levels and limited number of electrons per level

De Brogile 1921

Proposed particles act like waves and waves act like particles, being both at the same time, part of quantum theory

Heisenberg 1923

Showed you could never find exact position of electron, just predict where it’ll most likely be, called those regions orbitals and made the cloud model

Schrodinger 1926

Used theories of other scientists to make equation which proved energy was quantized and orbitals were essential, also originally proposed electron cloud model Heisenberg proved

Chadwick 1932

Discovered neutron in nucleus, led to creation of uranium 235 and nukes