Brief Nuclear Overview 1) Nucleons ­ neutrons+protons
2) Element notation
­­> Atomic number defines element ­ ISOTOPE
3) Unified mass unit ­ u 4) Particle masses
1 p = 1.007267 u
1 n = 1.008665 u
1 e = 0.000549 u
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Mass Energy Equivalence ­­­ E = mc2
Energy can be converted to mass
­­­ Pair Production
Mass can be converted to energy ­­­ Antimater annihilation, Nuclear Fission (atomic bomb)
Conservation of Energy = Conservation of (Energy + Mass) Conservation of Charge
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Working With Mass­Energy conversions in problems The mass, should always be a "missing mass" of some form. Difference of before vs. after in a reaction or mass "disappearing"
­ mass in kg , plug into E=mc2
­ mass in u, use conversion factor 1u = 931.5 MeV
Ex: a proton annihilates with an antiproton ­ how much energy is released
1) E = mc2 (use kg)
OR
2) 2 protons mass (use u)
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Mass Energy Concept ­ Binding Energy
Ex:
Carbon 12 (weighed) full atomIndividual Pieces of atom
­
­­
­­­
12.000 u 12.099 u
.099 u = 92.2 MeV
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2) Mass energy in nuclear reactions
­ Similar to binding energy problems but simpler, just find the difference in mass before vs after and convert it
EX:
How much energy is released in the reaction below
0.0188 u = 17.5 MeV
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1 p = 1.007267 u
1 n = 1.008665 u
1 e = 0.000549 u
Practice Problem
1) Determine the energy input to complete the following reaction
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2
He + Energy = 32He + 10n
mass in u .0076 u = 7.1 MeV
4 2He
4.0026
32He
3.0016 10n
1.0086 2) A positron (anti­electron) meets an electron and annihilates. How much energy is released in the interaction
1.64x10­13 J
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Fission ­ splitting of nucleus causing a chain reaction occurring over and over again releasing a lot of energy start with a high speed neutron spling the uranium 235
92
U + 10n à 236
92
U à 141 56 Ba + 92 36 Kr + 3(10n)
Before m = 236.052590 u After m = 235.866554 u
Fusion ­ merging together nuclei to form heavier element and release energy (the sun)
Ex (deuterium process)
3 ( 21H ) à 42He + 11H + 10n
3(2.0141u) à (4.0026u) + (1.0078u) + (1.0087u) + energy
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WORKBOOK Modern Physics Student Sheet – 3
1.) Which particles are most likely to be found in an atomic nucleus? (1) neutrons only (2) protons only (3) both protons and neutrons (4) both neutrons and electrons
2.) Which statement most accurately describes the interactaction which binds a nucleus together (a) long range and weak (2) long range and strong (3) short range and weak (4) short range and strong
3.) What is the force that holds the nucleus together (1) nuclear force (2) magnetic force (3) gravitational force (4) electrostatic force
4.) One universal mass unit is defined as (1) the mass of an electron (2) the mass of a proton (3) the mass of a carbon­12 atom (4) 1/12 the mass of a carbon­12 atom
5.) In the equation E=mc2, E may be expressed in (1) newtons/coulomb (2) joules/second (3) electron volts (4) coulombs
6.) As a star gives off energy in a thermonuclear reaction, the mass of the star (1) decreases (2) increases (3) remains the same
7.) Determine how many joules of energy would be produced if 2.5 x 10­3 kg of matter was entirely converted into energy
2.25 x 1014 J
8.) If the mass of one proton was totally converted into energy, the yield would be (1) 2.79 x 10 ­38 J (2) 5.01 x 10 ­19 J (3) 1.50 x 10 ­10 J (4) 9.00 x 10 16 J
1.5x10­10 J
9.) In a nuclear reaction, 9.90 x 10 joule of energy was released. ­13
Determine the mass equivalent of this energy
1.1x10­29 kg
10.) Sketch a graph that represents the relationship between mass and energy in the equation E = mc2
11.) Uranium has a mass of 235 u, Barium has a mass of 137.9 u, Krypton has a mass of 94.9 u and a neutron has a mass of 1.0 u. In the nuclear reaction where Uranium is bombarded by a neutron (U + neutron) the products of the reaction are Barium + Kryton + 3 neutrons + E, where E represents energy. The E is equivalent to a mass of (1) 0.2 u (2) 2.0 u (3) 2.2 u (4) 0.0 u
0.2 u
12.) The nuclear fusion reaction in the sun combines tritium (3.01695 u) with hydrogen (1.00813 u) to form Helium (4.00388 u) and energy. Find the energy released in this reaction in units of MeV
0.0212 u = 19.7 MeV
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Subatomic Physics & The standard model of matter
­ fundamental particles
­ particle accelerator
­ Quarks
(protons + neutrons) = Baryons
­ Antimatter
p
p
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Workbook 10
Subatomic Physics Student Sheet
1.) A baryon may have a charge of (1) ­1/3 e (2) 0 e (3) +2/3 e (4) +4/3 e
2.) An antibaryon is composed of (1) three quarks (2) one quark and two antiquarks (3) three antiquarks (4) two quarks and one antiquark
3.) What is the electric charge on a pion having quark composition u d 4.) What is the electric charge on a particle having a quark composition of d b
5.) A particle has a quark composition of dds. What is the charge on and classification of the particle? (1) ­1e baryon (2) +1 e baryon (3) ­1e meson (4) +1 e meson
6.) A particle has a quark composition of s u . What is the charge on and classification of the particle (1) ­1e bayon (2) +1e baryon (3) ­1e meson (4) +1e meson
7.) What is the mass of an antineutron in kilograms?
8.) The subatomic particles that make up protons and neutrons are called (1) electrons (2) positrons (3) leptons (4) quarks
9.) How much energy is involved when a positron and an electron collide an annihilate each other?
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Quick Nuclear Summary
∎ E = mc2 , only when mass in kg, 1 u = 931 MeV when mass in 'u' Used to find equivalence of energy or mass
m = missing mass, ex: ­ annihilation with antimatter: (m = 2 x particle mass missing)
charge must be conserved for 2 particles ­ nuclear reaction: m = mass difference before vs after, ­ binding energy: missing mass of separate pieces (p+n+e) vs total called mass defect
∎ Sub Atomic Physics ­ use chart in reference table to name particles
­ Quarks are smaller particles some matter breaks down into
­ Leptons dont break into anything else
­ Proton and Neutron are made of quarks and called Baryons
­ Charge of any particle is always a whole number (including 0)
­ Bar on top of a letter means anti matter, has opposite sign +/­ of that listed in the charge ex: 'u' quark in chart charge = +2/3 e, so u = ­ 2/3 e 12
THE END!
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