Radioactivity

• The total mass of a stable nucleus is always less than the sum of the masses of its constituent protons and neutrons.
• Mass Defect: the mass of nucleus is less than the sum of masses of protons and neutrons.
• binding energy: net energy required to decompose a nucleus into its components.
• Without the binding energy, the repulsion between the protons would blow this nucleus apart.
• The identity of an element is determined by the number of protons.
• Radiation came from unstable particles and spontaneously release energy in result in having daughter paticles
• Which part of the atom involves in the strong number of nuclear force?

  A) Protons and neutrons

  
• If the nucleus is too big, it releases helium nucleus (very stable particle) which is called alpha particles.
• Most of the helium in Earth came from the radioactive decay.
• Determine the resulting element of uranium-238 after alpha decay.

  A) Thorium-234

  
• The parent particle of this alpha decay is Americium-241.