Atoms and Isitopes

• Electrons orbit the nucleus at different energy levels called shells or electron clouds.
• Protons have a positive charge, electrons have a negative charge, and neutrons are neutral.
• The nucleus is made up of protons and neutrons
• The first two shells can hold up to eight electrons, while higher-energy shells have lower occupancy limits.
• Where does fusion happen?

  Star
• Where do chain reactions happen?

  Nuclear reactor
• Where does alpha decay happen?

  Nucleus of an atom
• Types of nuclear radiation:

  Alpha

  Beta

  Gamma
• Suggest what happened in 1932 to change the idea that atoms contained only protons and electrons.

  Neutrons were discovered
•  

  The nucleus of a uranium-235 atom must absorb a particle before the atom is able to split. What type of particle is absorbed?


  Neutron
•  

  The nucleus of an atom splits into smaller parts in a reactor. What name is given to this process?


  Fission
• Name another natural source of background radiation.

  Radon

  Cosmic Rays

  Rocks

  Food
• Name another artificial source of background radiation.

  X rays

  Nuclear power

  Nuclear accidents

  Nuclear weapon testing
• Why does an atom that decays by emitting alpha or beta radiation become an atom of a different element?

  Number of protons changes
• Isotopes


  the same number of protons but different numbers of neutrons
• Radioactive

  Substance that gives out radiation
• What is an alpha particle?

  A helium nucleus
• Beta decay does not cause the mass number of an atom to change.  Explain why not.

  number of neutrons decreases by one

  number of protons increases by one
• Explain why the teacher wears polythene gloves when handling radioactive materials.

  Prevents contamination which could cause contamination over a long period of time