aul`s note on the blog

THOMSON’S MODEL OF ATOM

 “ An atom consisted of a diffuse sphere cloud of positive charge with negative electrons embedded randomly in it” this model is called the plum pudding model.
  

A. Electrons
B. Spherical cloud of positive charge



GOLDSTEIN’S EXPERIMENT  
   
   
   


   
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Canal rays and cathode rays with opposite directions, so they must carry positive charge.

RUTHERFORD ‘S MODEL OF ATOM
- use alpha ( ) particles
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Lead block shield lead foil gold foil

Radioactive sample emits
Beam of  particles  
  zinc sulfide screen 


He found that :
1. Almost all of  particles passed through the foil undeflected.
2. Some ( ) particles experienced slight deflection
3. Only very small number of  particles suffered rather serious deflection
4. A much smaller number of  particles were bounced back toward the particle source

Rutherford suggested that :
1. Atoms consist of a positively charged nucleus surrounded by system of electrons
2. The volume of nucleus is extremely small compared with volume of atom.
3. Almost of the mass of the atom is concentrated in the nucleus.
4. The atom is mostly empty space because most of ( ) particles passed through the metal foil.

Rutherford suggested the existence of positively charged fundamental particles of matter in the nuclei of atom and it called proton.
Rutherford’s Model of Atom 



   

   





James Chadwick bombarded a thin sheet of beryllium with  particles , a very high energy radiation was emitted by the metal, it is named neutron

 +  +  

 is called …….