Alpha particle experiment + plum pudding + Bohr

• What is the alpha particle scattering experiment?

  -In 1909 scientists fired alpha particles at thin gold foil. Some particles passed through whereas some were reflected away which demonstrated that the atomic model was incorrect
• What did the experiement change about our current model?

  -It showcased that there is a centre ball of mass which we know as the nucleus and the electrons orbit around the nucleus on shells
• What is another name for the experiment?

  -The golden foil experiment
• What is an alpha particle?

  An alpha particle is a type of particle consisting of two protons and two neutrons, with a positive charge. It is a helium nucleus emitted by radioactive substances
• What was the plum pudding model?

  The plum pudding model was a model of the atom proposed by J.J. Thomson, which suggested that atoms were made up of a positively charged "pudding" with negatively charged electrons embedded in it.

  
• What were Rutherford's conclusions given after the golden foil experiment?

  -The plum pudding model couldn't be correct

  -Since most particles went through he concluded that the atom must be mostly empty space

  -The fact that some of the particles bounced back showed that there must be a very dense centre (nucleus , didn't know this yet)

  -Noticed that some of the particles were deflected at large angles

  The alpha particles have a +2 charge (positive) so it showed that at the centre there is a dense positive charge
• Overall Rutherford's model was correct but also incorrect in the way that his new model of the atom did not make scientific sense as it stated the atom would orbit the nucleus meaning it would eventually run out of energy and fall in making it unstable. But atoms are stable. This is where Bohr came in to make additions to Rutherford's atomic structure
• Bohr explained that the energy of the electrons remained fixed although they did orbit the atom as they remain at fixed orbits from the nucleus (we now know as shells) and has a fixed amount of energy. These were called discreet orbits.
• Difference between Bohr's model and our modern model is the existence of Neutrons and the nucleus being made up of them and protons with charged shells that the electrons orbit on