The atom

The atom

1. protons: 1 and 1+, neutrons: 1 and 0 charge and electrons:1/2000 and -1

   • mass number(top): number of protons and neutrons
   • atomic number(bottom) number of protons and same number of electrons

2. isotopes

   • same number of protons but a different number of neutrons

3. plum pudding model( JJ Thompson)

   • solid sphere solid positive mass and negative electrons embedded into it

4. The nuclear (Ernest Rutherford)

   • shot alpha particles at a very thin sheet of gold.
     • most of the particles went straight through and very few got deflected. this shows the plum pudding to be wrong
   • after further experiments Rutherford discovered the positive proton. The nucleus was hevier then it should have been so he predicted another thing was there which he called a neutron. James Chadwick discovered it

5. Bohr model

   • he said
     • electrons can only exist in fixed orbitals and each shell has fixed energy
     • when electrons move between shells electromagnetic radiation is emitted and absorbed
     • fixed frequency because the energy of shells is fixed