The Atom
All matter is made up of very small particles called atoms
All atoms are indivisible
Atoms cannot be created or destroyed
Cathode rays produced from cathode
They travel up vacuum tube towards anode => Maltese cross
Cathode rays fluoresce when they hit the glass
Cross cast a shadow
Cathode Rays: Cathode rays are steams of negatively charged particles called electrons
Cathode rays produced from cathode
They travel up vacuum tube towards anode
Move paddle wheel
Cathode rays travel in straight lines
Cathode rays cause glass to fluoresce
Cathode rays have enough energy to move a paddle wheel
JJ Thompson proposed structure of the atom => incorrect
Cathode rays deflected towards positive plate
This means that cathode rays have a negative charge
Conclusion => Cathode rays are made up of negatively charged particles called electrons
Determined charge of an electron
1.6×10-19
Alpha particles: 2 protons + 2 neutron
Bombarded gold foil with alpha particles
Observation | Conclussion |
Most particles passed straight through | Atom is mostly empty space |
Some deflect at slight angles | Small positive nucleus |
Few reflected back along their original paths | Nucleus is dense |
Discovered proton and nucleus
Disproved plum pudding model
Bombarded beryllium with alpha particles => discovered neutron
Relative Charge | Relative Mass | Location | |
Proton | +1 | 1 | Nucleus |
Neutron | 0 | 1 | Nucleus |
Electron | -1 | 1/1838 | Outside Nucleus |
All matter is made up of very small particles called atoms
All atoms are indivisible
Atoms cannot be created or destroyed
Cathode rays produced from cathode
They travel up vacuum tube towards anode => Maltese cross
Cathode rays fluoresce when they hit the glass
Cross cast a shadow
Cathode Rays: Cathode rays are steams of negatively charged particles called electrons
Cathode rays produced from cathode
They travel up vacuum tube towards anode
Move paddle wheel
Cathode rays travel in straight lines
Cathode rays cause glass to fluoresce
Cathode rays have enough energy to move a paddle wheel
JJ Thompson proposed structure of the atom => incorrect
Cathode rays deflected towards positive plate
This means that cathode rays have a negative charge
Conclusion => Cathode rays are made up of negatively charged particles called electrons
Determined charge of an electron
1.6×10-19
Alpha particles: 2 protons + 2 neutron
Bombarded gold foil with alpha particles
Observation | Conclussion |
Most particles passed straight through | Atom is mostly empty space |
Some deflect at slight angles | Small positive nucleus |
Few reflected back along their original paths | Nucleus is dense |
Discovered proton and nucleus
Disproved plum pudding model
Bombarded beryllium with alpha particles => discovered neutron
Relative Charge | Relative Mass | Location | |
Proton | +1 | 1 | Nucleus |
Neutron | 0 | 1 | Nucleus |
Electron | -1 | 1/1838 | Outside Nucleus |