Download 1991B5 A polonium nucleus of atomic number 84

1991B5
A polonium nucleus of atomic number 84 and mass number 210 decays to a nucleus of lead by the emission of an alpha particle of mass
4.0026 atomic mass units and kinetic energy 5.5 MeV. (1 atomic mass unit = 931.5 MeV/c2 = 1.66 x 10-27kg.)
a. Determine each of the following.
i. The atomic number of the lead nucleus
ii. The mass number of the lead nucleus
b. Determine the mass difference between the polonium nucleus and the lead nucleus, taking into account the kinetic energy of the alpha
particle but ignoring the recoil energy of the lead nucleus.
c. Determine the speed of the alpha particle. A classical (nonrelativistic) approximation is adequate.
d. Determine the De Broglie wavelength of the alpha particle.
1996B5
An unstable nucleus that is initially at rest decays into a nucleus of fermium-252 containing 100 protons and 152 neutrons and an alpha
particle that has a kinetic energy of 8.42 MeV. The atomic masses of helium-4 and fermium-252 are 4.00260 u and 252.08249 u,
respectively.
a.
What is the atomic number of the original unstable nucleus?
b.
What is the velocity of the alpha particle? (Neglect relativistic effects for this calculation.)
c.
Where does the kinetic energy of the alpha particle come from? Explain briefly.
d.
Suppose that the fermium-252 nucleus could undergo a decay in which a β- particle was produced. How would this affect the
atomic number of the nucleus? Explain briefly.
The unknown nucleus decays into the fermium nucleus and the alpha particle.
There is a little less mass on the product side of this nuclear reaction. This
decrease in mass is known as the mass defect. This decrease in mass is related
to the binding energy of the atom and its nucleus. This binding energy is converted
into the Kinetic Energy of the alpha particle as a flies away.
2002B7B
An experimenter determines that when a beam of monoenergetic electrons bombards a sample of a pure gas, atoms of the gas are excited if
the kinetic energy of each electron in the beam is 3.70 eV or greater.
(a)
Determine the deBroglie wavelength of 3.70 eV electrons.
(b)
Once the gas is excited by 3.70 eV electrons, it emits monochromatic light. Determine the wavelength of this light.
Experiments reveal that two additional wavelengths are emitted if the beam energy is raised to at least 4.90 eV.
(c)
In the space below construct an energy-level diagram consistent with this information and determine the energies of the photons
associated with those two additional wavelengths.