-
400
Democritus
Democritus believed that everything consisted of "atoms", which cannot be broken apart. He believed that atoms are indestructible and are perpetually in motion. He also believed that there are unlimited atoms, and kinds of atoms, of various shapes and sizes. *This date is B.C. -
John Dalton
Dalton expanded upon the ideas of Democritus, drawing a circle as the atom model. Dalton proposed that atoms are the smallest component of all molecules believing they combine in simple ratios. Dalton believed that atoms could not be destroyed. This model was found at http://everythingscience.co.za/grade-10/04-the-atom/04-the-atom-02.cnxmlplus -
Sir Joseph Thomson
Thomson discovered that there were smaller parts to the atom called electrons. In his model, the negatively charged electrons are floating around in a "soup" of positive charge. Thomson was awarded the Nobel Prize *This model was found at http://everythingscience.co.za/grade-10/04-the-atom/04-the-atom-02.cnxmlplus -
Period: to
Atomic Models
Timeline for models of the atom. -
Ernest Rutherford
Rutherford employed innovative radioactive technology to discover that the atom had a dense, positively charged core (although in reality it was positively and neutrally charged), surrounded by electrons, which are lighter. This model resembles a solar system. *This model was found at http://www.universetoday.com/56469/atom-diagram/ -
Niels Bohr
Bohr realized that electrons moved in certain paths around the nucleus, not randomly. His model had certain "energy levels" in which a certain amount of electrons circumnavigate the nucleus. *This model was found at http://everythingscience.co.za/grade-10/04-the-atom/04-the-atom-02.cnxmlplus -
Electron Cloud/Erwin Schrodinger
Schrodinger designed a model that shows the nucleus and where the electrons ought to be. The model is based on probability and is referred to as the cloud model. *This model was found at
http://www.regentsprep.org/regents/physics/phys05/catomodel/cloud.htm
