History & Basic Structure of Atoms






“Based on my thinking and discussions, I believe that there is a limit to the number of times that matter can be divided.  I will call these particles ‘atomos‘ or atoms.”

John Dalton
Responsible for 1st atomic theory: Atoms of the same element are identical and are different from atoms of other elements.
JJ Thomson
Discovered electrons with his Cathode Ray Tube (CRT) experiments.
Ernest Rutherford
Discovered the existence of the small positively charged nucleus of atoms with his Gold Foil experiment
Niels Bohr
Originator of Quantum Theory
Electron Cloud
Region around the nucleus where electrons may be found
Center of the atom; contains protons and neutrons
positively changed particle in the nucleus of an atom
neutral particle found in the nucleus of an atom
Negatively charged particle found in the area around the nucleus of an atom
Importance of protons
Determines the identity of an element
Importance of Neutrons
Responsible for the formation of different isotopes
Importance of Electrons
Responsible for the Reactivity of an element
JJ Thomson’s Atomic Model