Atomic Theory
About this set
Created by:
sunfishsailor06 on January 21, 2009
Subjects:
Classes:
Log in to favorite or report as inappropriate.
Order by
20 terms
Terms | Definitions |
|---|---|
 Democritus | Greek philospher that came up with the Atomic Theory |
| Atomic Theory | Atoms are solid and indestructible; different things contain different atoms; this theory by Democritus was rejected |
| John Dalton(1803) | First modern atomic theory |
| Dalton's atomic theory | All matter is made of atoms; All atoms of an element are identical, and different from atoms of other elements; Atoms cannot be created, divided or destroyed; Atoms combine in whole-number ratios to form compounds |
| J.J. Thomson (1897) | Discovered the electron; Determined the charge-to-mass ratio of electrons; "plum pudding model" |
| Robert Millikan (1909) | Determined the mass of an electron; "oil drop experiment" |
| Mass of an Electron | 9.1x10-28 g |
| Ernest Rutherford (1911) | Gold Foil experiment; Discovered the proton and nucleus; Determined that atoms are mostly empty space |
| Henry Moseley (1913) | Determined atomic numbers |
| Atomic numbers | Equal to the # of protons in nucleus |
| Neils Bohr (1913) | Created the planetary, or Bohr, model of the atom; |
| Bohr Model | Electrons move in specific circular orbits around the nucleus, based on their energy levels |
| James Chadwick (1932) | Discovered the neutron; Developed the Electron Cloud Model of the atom |
| Current Model (Electron Cloud) | Atoms are the smallest particle of an element that retains the physical properties of that element; The diameter of an atom is around 1x10-10m; Atoms are composed of three subatomic particles, called protons, neutrons, and electrons; The central part of an atom is called the nucleus |
| Structure of the Atom | Protons are positively charged particles found in the nucleus; All atoms of the same element have the same number of protons; One proton weighs 1 atomic mass unit (amu or u); Neutrons are particles found in the nucleus, but have no charge; One neutron also weighs 1 amu |
| Electrons | have a negative charge and are found outside the nucleus |
| Mass of an electron | .0006 amu, and is estimated as 0 |
| Atomic Mass (A) | is the sum of protons and neutrons in the nucleus |
| Isotopes | Atoms of the same element which have the same number of protons but different number of neutrons |
| Average Atomic Mass | average mass of isotopes; # that appears on periodic table |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.