LECTURE                               FISSION

In this lecture you will learn:

FISSION:  RADIOACTIVITY IS THE ENERGY OF THE NUCLEUS WHEN IT BREAKS DOWN
Everything with an atomic number of 84 and up is naturally radioactive

Radioactivity is totally independent of chemical reactivity (since it does not involve the outer electrons)

Radioactivity is not affected by heat, cold, melting, or reshaping.

There are 3 types of radiation, alpha, beta and gamma

Great youtube on fission click HERE andHERE

A good demonstration of alpha, beta and gamma radiation click HERE
ALPHA particles have:
a 2+ charge and a mass of 4 units, 2 protons, 2 neutrons, no electrons (like helium nucleus). 
When it leaves the nucleus, the element changes to an element with 2 less protons
-- it wont penetrate the skin
-- is harmful if inhaled or  swallowed
-  is attracted to an charged plate
BETA particles are nuclear electrons split off of a neutron. When they leave the nucleus, they leave behind a NEW PROTON which changes the element into one +1 proton higher.
- so neutron is composed of proton plus nuclear electron
-  may travel meters in air and moderately penetrating.
- Beta radiation can penetrate human skin, prolonged contact may cause skin
damage
- not to be ingested
GAMMA RADIATION ALSO COMES FROM THE NUCLEUS, often after alpha and beta particles are ejected.
   get rid of excess and destabilizing energy in photons or packets at specific wavelengths.
is not attracted to charged plates
travel many meters in air
- travels many centimeters in human tissue and most materials
is both penetrating and ionizing
-- X-rays are also penetrating
- are hazardous both internally and externally
Materials that will stop radioactivity


 
X-RAYS
 X-rays are NOT NUCLEAR radiation as it doesnt come from the nucleus.

X rays were discovered boiling off of a high voltage wire (is same principle as tube type TV electrons, which are simply not as high voltage.)

The electrons (e-) were attracted to a positively (+) charged plate, and hit glass and caused a greenish glow.  It was electron, but came from the inner electron orbits of an atom.

HOW ARE X-RAYS PRODUCED?

The anode (+) is a metal like tungsten. It is the "target". When the high energy e- hit the target, they slow down abruptly. The kinetic energy of their movement is converted into a photon of high energy, X-rays.


It is sort of like throwing a ripe tomato at a wall.  When it hits, the kinetic energy is converted and the "juice" of the tomato now has all the energy and flies off in all directions while the "tomato" ie the electron stays on the wall.


 
NUCLEAR BOMBARDMENT
Making radioactive materials or starting a reaction involves adding particles to the NUCLEUS to unbalance it.  "SPLITTING ATOMS" is not like bowling where you roll something fast enough to knock the pins all over, it is more like Bocce balls where you slowly roll a ball into the center and knock out something. 

Neutrons are used because not affected by repulsion of the protons.  Fast neutrons bounce off of the nucleus (billiards), slow neutrons slide into the nucleus (like bocce ball).

Nearly any element can be made radioactive by adding particles 3Hydrogen for example AKA tritium.  All elements except helium have a radioactive isotope. 

Elements below 83 with balanced neutrons and protons are not naturally radioactive. But just adding or subtracting one neutron will make them radioactive.  When there are more or less neutrons than protons, it is called an ISOTOPE of the element and is radioactive. 

All elements 83 amu and higher are naturally radioactive (82 AMU is lead) The nucleii higher than lead is just too large for stability. 

REVIEW QUESTIONS:

RADIOACTIVITY
Above what atomic number are elements naturally radioactive?
How does chemical activity affect radioactivity?
How does hot and cold affect radioactivity?
Discuss everything you know about alpha, beta and gamma radiation.
What is difference between gamma and X-radiation?
How is particle and gamma radiation different?
Which radiation is affected by magnets?  What are the charges of alpha, beta and gamma radiation?
Create a table comparing apha, beta and gamma radiation for the following characteristics
penetration, charge, particle composition
What is ionizing radiation?
What are  X-RAYS, where do they come from and how are X-rays produced?
NUCLEAR BOMBARDMENT
"SPLITTING ATOMS"
Why are neutrons used to split atoms and create isotopes?
ALL ELEMENTS EXCEPT ________ HAVE A RADIOACTIVE ISOTOPE
When there are more or less neutrons than protons, it is called an ________of the element.
How do smoke detectors work?