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Unit 3-3 notes pages 54-99
Closed system- a system that does not exchange matter or energy with the environment
Open System- system that exchanges matter or energy with the environment
Source Object- Object that provides energy for the energy transfer
Receiver Object- Object that gains energy from the energy transfer
Heat- the amount of thermal energy transferred from a region of higher temperature to a region of lower temperature
Conduction- transfer of thermal energy between materials by the collisions of particles
(Heat moves through contact.)
Thermal equilibrium- When temperature of materials that is in contact are the same
Radiation- Transfer of thermal energy from one material to another by electromagnetic waves (Heat moves through space.)
Convection- transfer of thermal energy by movement of particles from one part of a material to another (Heat moves through waves.)
Specific Heat- amount of thermal energy required to increase the temperature of 1kg of material by 1 degree Celsius
Thermal conductor- material through which thermal energy flows easily
Thermal insulator- Material through which thermal energy do not flow easily
*Nuclear reaction: A reaction in which the nucleus of one kind of atom changes into the nucleus of a different kind of atom.
Strong force-
A force that causes protons and neutrons to be attracted to each other.
Radioactivity-
When strong force is not large enough to hold a nucleus together tightly, the nucleus can decay and give off matter and energy
*Radioactive decay:
A nuclear reaction in which the nucleus of one kind of atom spontaneously changes into the nucleus of another kind of atom.
*Nuclear radiation:
The products of radioactive decay (alpha particles, beta particles, and gamma radiation)
Alpha particles:
The form of nuclear radiation having two protons and two neutrons
42He
Alpha particles cause considerable damage over small distances, but one is easily protected. (Paper stops them.)
Beta particles:
High-speed electrons that are a form of nuclear radiation. 0-1β
Beta and gamma rays do less damage, but reach long distances and are difficult to protect against.
Aluminum foil stops Beta particles.
Gamma radiation:
The most penetrating. They equal or surpass x-rays for energy.
00Y
Thick lead stops gamma radiation.
Three particles of the atom.
Neutrons 10n
Protons 11p
Electrons 00e-1
Transmutation-
A process of changing one element to another through nuclear decay
Transmutation(Bombardment) reaction
1) Target nucleus = The stable isotope to be bombarded(shot at)
{Larger on the reactant side}
2) Projectile = Particle fired at the stable isotopes
{Smaller on the reactant side}
3) Product = The heavy nucleus produced
{Larger on the product side}
4) Ejected particle = The light nucleus or particle emitted from the reaction.
{Smaller on the product side}
Example
? + protonß Gallium-71 + 3 Alpha
+ (11p) ß 7131Ga + 3 (42He)
Answer
Product ejected Target Projectile
Particle
Krypton-82 + protonß Gallium-71 + 3 Alpha
8236 Kr + (11p) ß 7131Ga + 3 (42He)
*Radioactive Decay-There are about 350 isotopes of the 90 elements. Of these 350 isotopes 70 are radioactive. Most of the radioactivity is above the Bi-83.
Half-life-
The amount of time it takes for half the nuclei in a sample of the isotope to decay
EX If the half-life of Hydrogen is 2 days, how many atoms of the original 4000 atoms will be present in 8 days?
Time Half life Particles will be =Cut in half
0 0 4000 were =Double the particles
2 days 1 2000
4 days 2 1000
6 days 3 500
8 days 4 250 250 atoms
Cloud chamber-
A device used to detect alpha or beta particle radiation.(Cold and saturated and detects radiation.)
Bubble chamber-
A device that detects and monitors the paths of nuclear particles(Hot and saturated and detects radiation.)
Geiger counter-
A device used to measure the amount of radiation by producing an electric current when it detects a charged particle
*Intensity=
The # of clicks / the unit of measure on the meter. [Counts per minute(cpm)]
*Background radiation=
The constant level of natural radioactivity.
Reading - Background = Source radiation
Watch 4 minutes to 7 minutes.
https://www.youtube.com/watch?v=s9PZNJ970M8
Nuclear fission-
A process of splitting a nucleus into several smaller nuclei
Chain reaction-
Series of repeated fission reactions caused by the release of neutrons in each reaction
Critical mass-
Amount of material required so that each fission reaction produces approximately one more fission reaction
Nuclear fusion-
Two nuclei with low masses are combined to form one nucleus of larger mass
One example is H+H à He
Tracer-
Radioisotope used to find or keep track of molecules in an organism
Metastable = When the alpha and beta decay leaves the nucleus in an excited state.
* Tissue damage is related to the extent of ionization created by radiation.
** Each series of natural radioactivity produces Lead-All large isotopes decay to form Lead.*
Energy from 1gram of fuel = 700,000gallons of octane fuel.
Polonium-212 3x10-7 seconds
Iodine-131 8 days
Hydrogen-3 12.3 years
Carbon-14 5730 years
Uranium-238 4.5 billion years
*The rate of radioactive decay is unaffected.
*Transuranium = Element made from Uranium ( 17 elements)
*Actinide series = The newly added series for the transuranium elements.
1930’s - U-238 use in weapons was discovered.
The first reactions were designed to produce Plutonium-239 for weapons.
Parts of a nuclear reactor.
1. Fuel rods =
Small steel rods where fission takes place.
97% UO2 Uraniun Dioxide - nonfissionable
3% U-235 fissionable
2. Control rods =
steel rods containing Boron or Cadmium that absorb neutrons.
3. Moderator =
A material that slows down neutrons so they can be absorbed better.
D2O, H20, and graphite H-2=D Deuterium
4. Turbine-
Device that spins and causes the generator to spin.
5. Generator=
Device that converts mechanical energy into electrical energy.
6. Cooling system=
A series of pumps and pipes “safely” releases heat into the environment.
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