FUSION – Releasing Energy

• Due to the strong nuclear force, it takes ENERGY to pull apart a nucleus: This is a BINDING ENERGY

  • It takes more energy to pull apart a Helium nucleus (2p + 2n) than a Deuterium nucleus (1p + 1n).
  • Most tightly bound element is Iron (Fe)

• 2p + 2n in a He nucleus

  • He nucleus in lower energy state than 4 protons in 4 H nuclei
  • 4H  He + energy!
  • He more tightly bound than 4H, so energy is emitted

• Energy and mass are really the same thing. (Einstein)

  • A He nucleus weighs 0.7% less than 4 P (because of the binding energy difference)
  • E=mc2 (Einstein!)
  • Compare 4 x proton mass to mass of He nucleus, and convert the difference to Energy
  • Energy released = 0.43 x 10-11 J

Notes: