Section 7.3

The process in which the nucleus changes gains or releases particles and energy The stronger the bond the more energy associated with it Small Change = Big Energy Chemical reactions involve only the Electrons of atoms Nuclear reactions involve the Protons, Neutrons and Electrons The Future will Involve Quarks

Chemical (Burn Coal)Nuclear (Uranium-235) 2 tonnes (2000Kg) of Coal = 1 g of Uranium Big Energy for such a Small Change Nuclear energy released is a million times greater than Chemical

Natural or Artificial (man-made) Natural: Some isotopes are naturally reactive and unstable (radioactive decay) Artificial: scientists can induce (create or speed-up) a nuclear reaction by bombarding a nuclei (making it unstable) with other nuclei or alpha, beta, and gamma radiation

Types of Nuclear Reactions

Fusion reaction involves combining particles Smashing 2 or more particles together to form a larger one that releases the extra energy Two smaller particles have more energy than is needed by one larger particle  release the extra Think about the energy required(input) and potential(output) from 2 cars (or people) compared to 1 larger car (or person) This involves small (light) particles To Fuse = To Make Whole (One)

Fusion is still experimental (can create but not sustain reactions) There are no (independently run) fusion reactors or weapons Minimal nuclear waste (formed isotopes are non- radioactive) 3 to 4 times more powerful than fission Naturally occurring (Sun) Not by man, too costly Technology is Insufficient ( can’t achieve and contain the high pressures & temperatures ) To Fuse = To Make Whole (One)

Fission reactions involve breaking apart particles Splitting 1 particle into 2 or more, while releasing energy Larger particles are more unstable due to the large number of (proton) interactions inside that tear (force) it apart Think about being uncomfortable or trapped, a lot of unnecessary energy is wasted and you are glad to release it This involves massive (heavy) particles. To Fizz = To Break-Apart (Pieces)

Fission is applicable (in use) There are nuclear fission reactors and weapons Dangerous radioactive isotope by-products limit fission’s usages Disposal of radioactive waste is a problem (dangerous and costly) Nuclear Power Generation: Reactors & Weapons To Fizz = To Break-Apart (Pieces)

All you need is to start the reaction. After the first, the reaction will continue on its own Chain reactions are famous for getting out of control  BOOM  The initial particle triggers multiple particles, so the reaction builds (speeds up).

To stop the rapid increase that may lead to a violent nuclear reaction Or use a material to absorb (remove) or moderate (slowdown) the extra bombarding particles (protons, neutrons, electrons) Scientists have to either control the fuel in the reaction (the uranium or other fissionable material)

[A tipping point or a threshold (beginning) of change] Fission As the isotopes become larger the energy released decreases Beyond Iron, the isotope requires more energy to survive (becoming too massive & unstable) Fusion As the split isotopes become smaller the energy released decreases Beyond iron, the 2 smaller isotopes require more energy to survive than the single larger one One of the last nuclear reactions that are exothermic One of the most abundant elements on earth

Neutrons represent a powerful tool for inducing (starting) nuclear reactions Neutrons are small enough to penetrate matter (fit through holes), but large enough to make a difference (hit by a car). Neutrons have no overall charge (repulsive forces). Alpha too big and has protons Beta smaller and has an electron Gamma has (virtually) no mass Anything else is a combination of no good or we do not have the technology to use it properly

Don’t Forget to Balance!!!! 2. The sum of the atomic charges (in the nucleus) on each side of the equation does not change (stays the same) 1. The sum of the mass numbers on each side of the equation does not change (stays the same)