Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

7 Cards in this Set

  • Front
  • Back
first idea about the atom
John Dalton
1. All matter is composed of tiny, indvisible partices called atoms
2.Atoms of the same element are identical, and are different from those of any other element
3. Atoms combine in simple, whole number ratios form compounds
4. Atoms may be separated, joined, or rearranged in chemical reactions. They may not be changed to form a new element.
J.J. Thomson
discovered electrons using cathode rays
Ernest Rutherford
discovered a small concentrated positive area (nucleus) in the atom as a result of the gold foil experiment
-atom is mostly empty space
Neil Bohr
studied the atomic sectra of H
-discrete wavelengths of light seen because of specific amounts of E being emitted
-planetary model
Quantum Mechanical Model
E not in a fixed path rather are restricted to a specific 3 dimensional space(known as cloud or orbital)
95% probability of finding e within a particular cloud
James Chadwick
more mass in nucleus than could be accounted for by the proton
discovery of neutron particle in nucleus with slightly more mass than a proton but unchanged