1. Nuclear Physics and Radioactivity

2. Vocabulary
alpha particle - positively charged particle consisting of two protons and two neutrons. (Helium nucleus)
atomic mass number (A) - the number of protons and neutrons in the nucleus of an atom.
atomic mass unit - the unit of mass equal to 1/12 the mass of a carbon-12 nucleus; the atomic mass rounded to the nearest whole number is called the mass number.
atomic number (Z) - the number of protons in the nucleus of an atom.
beta particle - high speed electron emitted from a radioactive element when a neutron.
decays into a proton
binding energy – the energy required to completely separate the nucleus into its individual protons and neutrons.
element - a substance made of only one kind of atom.
isotope - a form of an element which has a particular number of neutrons, that is, has the same atomic number but a different mass number than the other elements which occupy the same place on the periodic table.

3. Vocabulary
mass defect - the mass equivalent of the binding energy in the nucleus of an atom by E = mc2
neutron - an electrically neutral subatomic particle found in the nucleus of an atom
nuclear reaction - any process in the nucleus of an atom that causes the number of protons and/or neutrons to change
nucleons - protons or a neutrons
strong nuclear force - the force that binds protons and neutrons together in the nucleus of an atom
transmutation - the changing of one element into another by a loss of gain of one or more protons

4. Equations and symbols where ΔE = binding energy of the nucleus
Δm = mass defect of the nucleus
c = speed of light = 3 x 108 m/s
u = atomic mass unit
X = element symbol
A = atomic mass number (number of protons and neutrons)
Z = atomic number (number of protons)

5. electron orbitals around the nucleus
Particle
Symbol
Relative mass
Charge
Location
proton 1 +1
nucleus
neutron
electron
or e- -1
electron orbitals around the nucleus

6. neutral → #protons = # electrons = 26
Find the number of protons, electrons and neutrons in a neutral atom of iron.
# protons + #neutrons
# protons
26 protons
30 neutrons
neutral → #protons = # electrons = 26

7. MASS is transferred to ENERGY
Before
After M5 M2 M3 M1
Eo Ef
< = M4
Mo Mf
> =
Eo = Ef + (Mo-Mf)c2
Eo = Ef + (Δm)c2
MASS is transferred to ENERGY

8. p n

9. Mass defect is responsible for the binding energy. Ebinding = (Δm)c2

10. Calculate the binding energy of Nitrogen
Calculate the binding energy of Nitrogen. The atomic mass of Nitrogen is u.
Nucleon
Mass (u)
Proton
Neutron
7 protons
7 neutrons
Mass of individual protons and neutrons
7( u) + 7( u) = u
Δm = u – u = u

11. Transmutation of nitrogen into carbon
Nuclide/particle
Mass (u)
neutron
proton
Mass of products
u u = u
Mass of reactants
u u = u
Δm = u – u = u

12. Nuclear fusion – The joining of two small nuclei to form one large nucleus. The mass of the smaller nuclei is greater than the mass of the large nucleus. High temperatures are required for fusion.
Example: the sun
Nuclear fission – Splitting a large nucleus into two smaller nuclei. The mass of the large nucleus is greater than the two smaller nuclei.
Example: Nuclear power plant
In both cases the mass of the products is less than the mass of the reactants, which results in a mass defect. The mass is converted to energy according to the equation E = (Δm)c2

13. Binding energy per nucleon vs. mass number
Iron (Fe) staple
fusion
Fission
Binding energy
Per nucleon
(MeV)
Mass number

14. Fusion Examples: Nuclide Mass (u) 1.007825 2.014101 3.016049 3.016029

15. Mass of reactants
u u = u
Nuclide
Mass (u)
Mass of products
u u = u
Δm = u – u = u

16. Fission Example:
absorbs a neutron and splits into and , Write the equation for the nuclear reaction and calculate the energy released in this reaction. Z
symbol A
Mass (u) 92 U
236 42 Mo
100 50 Sn
126

17. Fission Example:
absorbs a neutron and splits into and , Write the equation for the nuclear reaction and calculate the energy released in this reaction.

18. Z symbol A Mass (u) 92 U 236 236.045563 42 Mo 100 99.907476 50 Sn 126
Mass of products
u u =
Mass of reactants
u u + 11( u) = u
Δm = u – u = u

19. Radioactivity – Particles are randomly emitted from an unstable nucleus in order to become more staple. These are the different particles emitted. β+
positron
High Energy
Photons
gamma β-
Beta α
Alpha
symbol
Name

20. Nuclear Equations:

21. Nuclear Equations:
234 90
Alpha decay

22. Nuclear Equations: -1
Beta decay

23. Nuclear Equations: 4 2
Transmutation

24. Nuclear Equations: -1
So a neutron is the combination of a proton and an electron