• Ernest Rutherford was a New Zealander chemist and physicist.
• He studied radioactivity and discovered the concept of radioactive half life.
• Rutherford continued the research of his mentor, J. J. Thompson.
• In his research of the atom, he discovered the existence and properties of alpha, beta, and gamma particles.
• Rutherford also conducted the famous gold foil experiment.
  • This experiment allowed rutherford to discover the nucleus and modernize the atomic model.

• A nuclear reaction is a reaction that effects the nucleus.
• Transmutations are changes in the nucleus that change one chemical element or isotope to another. This equation is an example of a nuclear reaction because the reaction changes the nucleus.
  +=
• As you can see, the mass number, 9, changes to 13 and the atomic number,4 changes to 6 after adding the Helium particle, He. This means that the nucleus was changed and therefore it is a nuclear reaction.
  
  A reaction in terms of the particles will look like this:
  + =
  
• Nuclear stability is how stable the nucleus is some nuclei are more stable than others.
• The "strong nuclear force" holds the nucleus together.
  • The ideal ratio between protons and neutrons is 1:1.
    

 

• Thompson's work on the atom postulated that electrons are stuck in the atom in random places. Rutherford attempted to expand on Thompson's work.
• Rutherford conducted the Gold Foil Experiment.
• This experiment was intended to verify the structure of the atom (which was the Plum Pudding Model at the time).
• Rutherford used an extremely thin piece of gold foil and fired alpha particles,, at the foil.
  The experiment looked like this:
  
  
  
  
• Rutherford shot the alpha particles at the foil, which was so thin that they would pass through and create light on the screen that was surrounding the foil.
• Based on Thompson's model of the atom, Rutherford expected the experiment to look like this:
  
  
• This would result in light shining on only one spot on the other side of the foil.
• But instead Rutherford saw many spots of light all around the foil.
• What actually happened was different from what was expected. This is what happened in the atom:
  
  
• The alpha particles actually bounced off a positively charged area in the center!
• How did this happen? Rutherford determined that atoms must have something in the center that is getting in the way of the alpha particles.
• This thing was called the nucleus.
  • The nucleus is filled with positively charged particles, protons, and neutral particles, neutrons.
  • Rutherford showed that the nucleus was in the center and the electrons surrounded it.
  • Rutherford knew that the nucleus was positive because the alpha particles are positive and bounced off.
    
    
    
• Thus the new model for an atom was born:
  
  

• Alpha, Gamma, and Beta particles are different kinds of particles that play a role in radioactive decay.
• There are three kinds of radioactive decay: Alpha decay, Beta decay, and Gamma decay.
• Radioactive decay is when an unstable nucleus emits or loses energy by releasing different particles.
• This can happen when the nucleus transforms into a different nucleus, like in a nuclear reaction.

 

 

 

Alpha Decay:

• Nuclear Symbol:
• Symbol: 
• Alpha decay is when an alpha particle is released from the nucleus.
• This is basically a helium nucleus, 2 electrons, 2 protons.
• Alpha particles cannot pass through animals or people and don't do damage to people if they come in contact.

Beta Decay:

• Nuclear Symbol:
• Symbol: β
• Beta decay is when a neutron splits into a proton, which is positive, and an electron, which is negative.
• Beta particles can't pass through humans and therefore cannot do any harm.

Gamma Decay:

• Gamma decay is when a nucleus changes from ma higher energy level to a lower energy level.
• This can happen when it emits photons.
• Gamma particles can pass through humans. This is very dangerous because it can mutate and change particles in your body and cause cancer.