The Atom Flashcards
Diffusion is
The spreading of particles from a region of high concentration to a region of low concentration
State John Daltons Atomic Theory
- Matter is made of small particles
- He called these particles atoms.
- Atoms are indivisible and cannot be broken into smaller parts
What was Williams Crookes contribution to the discovery of the electron
- Wanted to prove there was something coming out of the negative end of battery.
- Used a vacuum tube
- Found radiation coming from cathode(negative)
- Placed Maltese cross inside tube and noticed a shadow forming
- Knew that the Maltese cross had to be blocking something
- Called these invisible rays cathode rays
Crookes Second experiment?
- Set up cathode rays to hit a paddle wheel using a battery
- When the battery was turned on the paddle wheels moved
- Something strong enough had to be pushing it
Crookes Conclusion
Cathode rays travel in straight lines
They cause glass to glow/fluorescent
They have enough energy to move a paddle wheel
JJ Thompson contribution
- Wanted to prove if these cathode rays were positive or negative
- Passed narrow beam of cathode rays between charged plates.
- Using electromagnet he discovered that streams of electrons were deflected towards positive plate.
- Calculated mass/ charge ratio
Who came up with the name Electron
George Stoney
Cathode Rays are
Streams of negatively charged particles called electrons
Robert Milikan contribution
- Wanted to find the exact size of a charge of electron and calculate its mass
- Ionised air molecules and sprayed oil into machine
- The oil picked up electrons lost from air
- Had two charged plates
- Charged plates suspended the oil in mid air and the charge of the oil drop was calculated
JJ Thomson Plum Pudding
Simple structure of an atom describing it as a sphere with positive surface and negative charges placed randomly around the surface to cancel out the charge
Ernest Rutherford discovery of Nucleus
- Bombarded thin leaf of gold foil with positively charged alpha particles.
- He discovered:
Many went straight through
Some were deflected
Some were reflected back along their own path
Small core in centre called nucleus
Ernest Rutherford Discovery of Proton
Discovered positive charged particles were given off when oxygen and nitrogen were bombarded with alpha particles
The nuclei of the atoms were breaking up and protons were given out
James Chadwick discovery of neutron
Bombarded beryllium with alpha particles and discovered that particles with no charge were released from the nucleus.
They had the same mass as proton
Subatomic particles
Proton, Neuton and Electron
Proton is located in nucleus with a charge of 1 and mass of 1 a.m.u
Electron is located outside nucleus with a charge of -1 and mass of 1/1838 a.m.u
Neuton is located in nucleus with a charge of 0 and mass of 1 a.m.u
an electron is
A subatomic particle
