 Splitting a large nucleus into two smaller nuclei  Usually begins by bombarding (shooting at) nucleus with a neutron  become unstable  Nucleus split into 2 (roughly half the mass each, but not usually equal)

Tip to recognize FISSION Equations:  Usually involved “big” isotopes breaking into 2

 Nuclear fission reactions produce a lot of energy (Comes from converting mass to energy E=mc2)  Can produce more than 2 nuclei To figure out the missing part of the equation:  do the math  find the identity of element using atomic #  Can produce/ require multiple neutrons, so make sure that you have accounted for the coefficient in front of 1n 0 **Let’s look at Sample Problem on p. 314

 Fission bomb= Atomic bomb  Keep two separate masses of Uranium or Plutonium.  The moment they combine (by implosion, or forcing two parts together), the radioactive material will reach “critical mass” and will react faster and faster until the material is used up  EXPLOSION!!!

E.g. Bomb dropped in Hiroshima and Nagasaki

 Basic principle  start CHAIN REACTION of Fission Reactions  Usually use Uranium-235  Use a moderator to control chain reactions (can use heavy water, cadmium or boron rods to absorb neutrons) E.g. CANDU reactors (Canadian Deuterium, and Uranium)

 Process occurs in the SUN (supply energy needed on Earth to sustain life!)  “Fusing” or joining of two small nuclei to make one large nucleus Tip to recognize FUSION Equations:  Usually involves “smaller” isotopes (Helium, Hydrogen, Deuterium, Tritium etc.)

Hydrogen  1p, 1 e; 0 n Deuterium  Hydrogen atom with 1 p, 1 e and 1 n Tritium  Hydrogen atom with 1 p, 1 e and 2 n

Simplest fusion equation How to make Helium atoms: 0 e (positron) +1

FUSION REACTIONS  Hydrogens undergo fusion to become He  2 Helium nuclei fuse to make Beryllium  Beryllium and Helium fuse to make Carbon!

 Fusion bomb = Thermonuclear bomb =Hydrogen bomb  Use energy from a fission bomb to power fusion bomb (bomb within a bomb)