Atomic History, Mo and Josh

Democritus was born; In Abdera, Greece

Democritus dies; In Abdera, Greece

Democritus discovers atoms He thought the world, including human beings, is composed of very small particles called "Atomos"

All matter consists of small particles called atoms -Atoms are indestructible -Atoms are solid but invisible -Atoms are homogeneous -Atoms differ in size, shape, mass, position, and arrangement -Solids are made of small pointy, atoms -liquids are made of large round atoms -oils are made of very fine, small atoms that can slip past each other

John Dalton was born; Cumberland, England

John Dalton dies; In Manchester, England

John Dalton discovers atoms He believed every form of matter was made up of small individual particles

Experimented on gases and atmospheric pressures

The tiny particles were called atomos -Believed that atoms of different elements could be identified by their differing atomic weights -Atoms cannot be created or destroyed

JJ Thompson was born In Cheetham Hill, Manchester, United Kingdom

JJ Thompson dies Cambridge, United KIngdom

Discovered the idea of the electron of an atom

Experimented with cathode ray tube: an electrical current was passed through the tube which made a stream of particles glow showing there was something there

-Electrons have a very large charge for their mass -Electrons have a negative charge -Electrons are extremely small

Robert Millikan was born In Morrison, Illinois

Robert Millikan dies In San Marino, California

He discovers the charge of an electron, or the elementary charge

Experimented with the Oil drop: drop oil between two electrodes, measure force of droplets passing through the electrical field and the field itself, able to determine the charge of an electron

The elementary charge equaled 1.5924(17) x 10^-19 Coulombs (C) . . .

Ernest Rutherford was born In Brightwater, New England

Ernest Rutherford dies In Cambridge, United Kingdom

Rutherford discovers the nucleus, proton, and alpha/beta particles

Experimented with Gold foil: fired a beam of alpha particles through a piece of gold foil and watched as it passed through and some particles that deflected the straight path.

Atoms have a vast amount of empty space that allows any particle to pass through them .

Niels Bohr is born In Copenhagen, Denmark

Niels Bohr dies In Copenhagen, Denmark

Discovered the electron and constructed the famous Bohr model

Bohr Model: showed the atom as a positive charged nucleus surrounded by orbiting electrons.

-Electrons move around the nucleus in orbits. -Energy in atoms is quantized .

Werner Heisenberg was born In Wurzburg, Germany

Werner Heisenberg dies In Munich, Germany

Heisenberg Discovered a way to formulate quantum mechanics in term of matrices

Uncertainty Principle: states that the more precisely the position of some particle is determined, the less precisely its momentum can be known, and vice versa.

-Absolute causal determinism is impossible .