The Atom (chpt. 2) Flashcards
Daltons atomic theory
- All matter is made up of very small particles called atoms
- All atoms are indivisible, they cannot be broken down into simpler particles
Who discovered the electron
J.J Thomson (using cathode rays)
What did J J Thomson discover
Electrons using cathode rays
Plum pudding model
What was the plum pudding model
A sphere of positive charge with negative electrons embedded in it at random
What are cathode rays
Streams of negatively charged particles called electrons. They travel in straight lines from the cathode to the anode and are deflected by electric and magnetic fields and have sufficient energy to move a small object such as a paddle wheel
Helium nucleus
Properties of cathode rays
Travel in straight lines
Deflected by electric & magnetic fields
Have sufficient energy to move a small object (paddle wheel)
Who discovered cathode rays
William Crookes
What did William crookes discover
Cathode rays
Who discovered the charge and mass of the electron
Robert Millikan
What did Robert Millikan discover
Charge of an electron (using oil drop experiment)
Mass of electron (using e/m)
What did Ernest Rutherford discover
The nucleus (by bombarding a thin piece of gold foil with alpha particles)
The proton
Rutherford structure of the atom
Nucleus containing protons which was surrounded by an electron cloud where electrons are located (DIAGRAM)
Ernest Rutherford - Alpha particle experiment
Ap pass straight through foil
Some deflected at large angles
Small number reflected back along original paths
Most of the atom is empty space
Repelled when they pass near the small, positive nucleus
Small number collide head on with the small, dense nucleus
Who discovered the neutron
James chadwick
How did Thomson account for the fact that atoms are electrically neutral
Plum pudding model
