1. The power of splitting an atom
Fission
The power of splitting an atom

2. Expectation 2: Nuclear reactions & energy
When atoms are split by any nuclear reaction, including fission, energy is released because some of the matter is changed into energy.
 E=mc2
When many atoms are splitting or decaying, this makes enormous amounts of energy.

3. Expectation 3: Nuclear Fission
A neutron hits a large fissionable atom and causes it to become unstable then split into two smaller atoms releasing neutrons and energy.

4. Expectation 4: Chain reaction
a sequence of “reactions” where a product or by-product causes additional “reactions” to take place
Examples: Dominos, pile up of fender benders at a red light

5. Expectation 4: Nuclear chain reaction
* Successive fission events
This one is uncontrolled, all
neutrons are allowed to
hit other atoms.

7. Expectation 4: Subcritical & critical mass
Subcritical mass- not enough material is present to make a chain reaction continue
Analogy: throwing paper wads (neutrons) when we were spread out
Critical mass- the amount of material needed to make a chain reaction keep going
Analogy: throwing paper wads (neutrons) at each other when we were squished together.

9. Pg 21 # 12: Controlled chain reaction
some of the neutrons are absorbed by another material and not allowed to hit other atoms. Only some neutrons cause more fission reactions. Picture by Glencoe division of Macmillian/McGraw-Hill Publishing