Atomic Theory: Assignment 1

Newton

Apr 21, 1704

Proposed a mechanical universe with small solid masses in motion.

Dalton

Apr 21, 1803

Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass.

Maxwell

Apr 21, 1873

Proposed electric and magnetic fields filled the void.

Thomson

Apr 21, 1897

Used a CRT to experimentally determine the charge to mass ratio (e/m) of an electron =1.759 x 10 8 coulombs/gram. Studied "canal rays" and found they were associated with the proton H + .

Rutherford

Apr 21, 1898

Using alpha particles as atomic bullets, probed the atoms in a piece of thin (0.00006 cm) gold foil. He established that the nucleus was: very dense, very small and positively charged. He also assumed that the electrons were located outside the nucleus. Also studied radiations emitted from uranium and thorium and named them alpha and beta. 1898 - 1911

Einstein

Apr 21, 1905

Published the famous equation E=mc 2 or The Theory of Relativity

Bohr

Apr 21, 1913

Developed an explanation of atomic structure that underlies regularities of the periodic table of elements. His atomic model had atoms built up of successive orbital shells of electrons.

Heisenburg

Apr 21, 1927

Described atoms by means of formula connected to the frequencies of spectral lines. Proposed Principle of Indeterminacy - you cannot know both the position and velocity of a particle.