Change the nucleus-change the atom Nuclear changes involve the nucleus (protons and neutrons). Chemical changes involve the electrons (ionic, covalent bonds) Physical changes involve electrons (hydrogen bonds, metallic bonds)
The FermiLab Particle Accelerator
Hydrogen gas is converted into hydrogen ions here
The linear accelerator
accelerates the protons to 70% of the speed of light with 400 million electron volts (MeV)
The booster ring bends the proton beam into a circular path.
The Tevatron particle accelerator is 4 miles in circumference.
The Tevatron accelerates particles to energies of 2 trillion electron volts (TeV).
Particle speeds approach 95% of the speed of light.
When these particles collide, conditions simulating the early universe are produced.
Cyclotron: Underground tunnel
Cyclotron: Proton Gun
Lead into Gold
A change in the number of protons in the atomic nucleus producing an atom with a differ atomic number.
continued The first was performed by Lord Rutherford in 1911.
continued Nitrogen-14 was bombarded with alpha particles producing oxygen-17 and protons.
N + He O + H This is a nuclear equation – what is balanced? Mass and number of protons (positive charge)
A nuclear reaction in which a very heavy nucleus is split into two approximately equal fragments. Complete the labs and write down observations and conclusions
First Atomic "Pile"
December 2, 1942 at 3:25 pm
The Gadget
July 16, 1945 at 5:29:45 am
Trinity at 10 seconds
Ground Zero
"Little Boy" Hiroshima, Japan August 6, 1945
"Fat Man" Nagasaki, Japan August 9, 1945
A nuclear reaction in which two or more small nuclei are forged together to form one larger nucleus.
Hydrogen fuses to produce helium, helium fuses to make lithium, etc. Most stars stop fusing elements at iron. Supernovas are needed to make heavier elements with uranium being the heaviest naturally occurring element.
Fusion Reactor
Fusion Issues: 100 million o C activation stability reliability heat lost to environment plasma interactions
Hydrogen Bomb – a thermonuclear device Uses Tritium (Hydrogen-3) to boost the explosive power.
First Hydrogen Bomb
"Fat Man"contained 6.15 kg of plutonium, of which only 1 kg fissioned into lighter elements.
Of this 1 kg, ONE GRAM of mass was converted into heat, light and radiation.
Because a bound system is at a lower energy level than its unbound parts, its mass must be less than the total mass of its unbound parts. The mass of the nucleus (whole) is less than the sum of its protons and neutrons (parts)
A dollar bill has a mass of about 1 gram.
E = (mass separated - mass bound ) c 2
E = mc 2 E/m = C 2 = (299,792,458 m/s) 2 / 1 kg 9 X joules / kg = 9 X J / g
That is equal to 43 million pounds of TNT, or 25 million kilowatt-hours of electricity.
Grand Coulee Dam, in central WA, is the largest hydroelectric generator in the U.S.
Its 33 turbines need almost 4 hours to produce 25 million kw-hours of electricity.
Mass Defect E = mc 2 means there is a change of mass associated with any energy change Energy is required to hold the nucleus together. Energy is released during fission – 1 kg of uranium = kg of coal The mass of the nucleus is always less than the sum of the individual protons and neutrons contained therein – MASS DEFECT = m in Einstein’s Equation
Mass Defect for Helium 2 protons = (2)( amu) = 2 neutrons = (2)( amu) = 2 electrons = (2)( amu) = Total Actual Mass = amu Mass Defect = amu (1 amu = x kg) x kg Energy = mc
What is the mass defect for Lithium-6? (mass of amu) How much energy from a total mass defect of U- 238 (actual mass = amu)?
Electric Energy Conversions Locate an electric bill at home and note the kWh (kilowatt-hours) used. Use dimensional analysis to convert kWh to kg of coal burned and its equivalent in Uranium-235 fuel. – 1 kWh = 3.60 x 10 6 J – U-235 undergoes beta decay giving a total disintegration energy of 4.68 MeV – 1 MeV = 1.61 x J – Carbon produces kJ per gram burned
Nuclear Reactor
Chernobyl, USSR - April 25 & 26, 1986 Nuclear Reactor Disaster
Chernobyl, USSR - April 25 & 26, 1986
Chernobyl Reactor Meltdown
Chernobyl Radiation