Preparation problems

43-4) Write the symbol for germanium isotope with 44 neutrons.
Germanium (Ge) has 32 protons, so Z=32.
A is the number of protons & neutrons, so that's 32+44 = 76. The symbol is therefore
76 Ge
32
43-5) How do the number of nucleons and the nuclear charge compare in the two nucleii 3517Cl and 3519K?
Both have the same number of nucleons (35), but the Potassium (K) has two more protons than the Chlorine (Cl), so it has the greater nuclear charge.
43-19) Find the total binding energy of sodium-32, given its atomic mass of 239.052157 u.
Notice that the mass given is the atomic mass, not the nuclear mass that we need for Equation 43-3. The difference is the mass of the electrons. We could subtract the mass of 11 electrons off of the atomic mass, but this would lead to an error since there is binding energy associated with the electrons as well. The accurate way to correct for this is to use the mass of a Hydrogen atom in place of the proton mass in Eq 43-3. This mass will include the electrons in the calculation.

Eb = Zmpc2 + (A-Z)mnc2 - mNc2
    = 11 (938.946 MeV/c2) c2 + (23-11)(939.566 MeV/c2) c2 - (22.989767 u )(931.494 MeV/c2/u) c2
    = 188.3 MeV ( = 30.128 x 10-12 J )

(Note: You can also do this in kg and Joules as follows)
Eb = 11 (1.674x10-27 kg)(3x108 m/s)2 + (23-11)(1.67493x10-27 kg)(3x108 m/s)2
- (22.989767 u)(1.66054x10-27 kg/u)(3x108m/s)2
    = 30.128 x 10-12 J ( = 188.3 MeV)

43-21) The mass of a Lithium-7 nucleus is 7.01435 u. Find the binding energy per nucleon.
Eb = Zmpc2 + (A-Z)mnc2 - mNc2
    = 3 (938.272 MeV/c2) c2 + 4 (939.566 MeV/c2) c2 - (7.01435 u )(931.494 MeV/c2/u) c2
    = 39.4 MeV

but this is Total binding energy of the nucleus. The biding energy per nucleon is
(39.4 Mev)/(7 nucleons) = 5.6 MeV/nucleon

(Note: this one can also be done in kg and Joules just as #19)

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