Section 7.3
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
The process in which the nucleus changes
gains or releases particles and energy
Chemical (Burn Coal)
2 tonnes (2000Kg) of Coal
Nuclear (Uranium-235)
=
1 g of Uranium
Big Energy for such a Small Change
Nuclear energy released is a million times greater than Chemical
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
Natural or Artificial (man-made)
Types of Nuclear Reactions
To Fuse = To Make Whole (One)
• 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
Naturally occurring (Sun)
• 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 nonradioactive)
• 3 to 4 times more powerful
than fission
Not by man, too costly
Technology is Insufficient
(can’t achieve and contain the high
pressures & temperatures)
To Fuse = To Make Whole (One)
To Fizz = To Break-Apart (Pieces)
• 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.
Nuclear Power Generation:
Reactors & Weapons
• 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)
To Fizz = To Break-Apart (Pieces)
The initial particle triggers multiple particles,
so the reaction builds (speeds up).
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 
Scientists have to either control the fuel in the reaction (the
uranium or other fissionable material)
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)
Fusion
Fission
As the isotopes become
larger the energy
released decreases
Beyond Iron, the isotope
requires more energy to
survive (becoming too
massive & unstable)
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
[A tipping point or a threshold (beginning) of change]
One of the last nuclear reactions that are exothermic
One of the most abundant elements on earth
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
Neutrons represent a powerful tool for inducing (starting) nuclear reactions
1. The sum of the mass numbers on each side of the equation does not
change (stays the same)
2. The sum of the atomic charges (in the nucleus) on each side of the
equation does not change (stays the same)
Don’t Forget to Balance!!!!