P4 - Atomic Structure

P4 - Atomic Structure

1. structure of atom

   • nucleus
     • electron
       • charge=1
       • mass= tiny
     • proton
       • mass= 1
       • charge=+1
     • neutron
       • mass=1
       • charge=0

2. history of atom

   • democritus
     • atoms are invisable
   • john dalton
     • atoms are building blocks there are different types
   • jj thompson
     • plum pudding model
       • solid ball off positive charge dotted with negative charge
   • james chadwick
     • discovered neutrons
   • niels bohr
     • electrons are in cells

3. Types of radiation

   • Alpha
     • charge 2+
     • stopped by a few cm in the air
     • mostly ionising
     • mass 4
   • Beta
     • fast moving electron
     • charge -1
     • mass 1/1832
     • stopped by AL foil
     • fairly ionising
   • gamma
     • mass 0
     • Charge 0
     • weekly ionising
     • stopped by a few meters of thick lead and concreate