Physics既Nucluear同Radioactivity

(1) atomic mass unit use a (1/12) neutral Carbon12 atom as standard, so use the mass in kg of C12 provided and divide it with 12 and use E=mc^2, energy is that mass time 3E8's square
(2)that is to referenceing that He3 atom with respect to C12 atom that you can just divide the exact mass of an C12 atom by 4 so that it is for comparing atom with 3 nucleon and you deduct that with He3's mass, this would give you the difference of mass defect, since He3 should have smaller mass defect, the mass would be higher than 3amu, so would be negative, the absolute value of this would be the mass defect of He3 , use E=mc^2 to convert this into energy in J

(3) what do you mean by -1e0 and 30n1

(2)atomic number is proton number, the element with n atomic number = nth element in periodic table , 8 should be oxygen, 13 should be Aluminium, 21 is Sc, 34 is Se, 55 is Cs, 89 is Ac


(3)By E=mc^2,
0.453x(3x10^8)^2
1000x10^6/(3x10^8)^2

(4)4xmass of atom of H1-mass of He4, you get mass defect, use E=mc^2 to get energy, you find the (mass of a H1 atom)^-1 to get how many number of H1 atom is equal to 1kg and multiply this with the energy difference you have just calculated

(5) (amux6 minus mass of a Li6 atom)/6
(amux238 minus mass of a U238 atom)/238
this give the mass defect per number of nucleon , the larger, the more energy had been released from the formation of that atom, hence the more stable, the answer should be uranium 238
http://en.wikipedia.org/wiki/Nuclear_binding_energy

2013-11-20 23:20:06 補充：
X= 91Pa239, total nucleon number unchanged=238+1=239, a neutron is decayed into proton and an electron
Z=54Xe143, Sr+Z: total nucleon=235+1-3=233, that of Z=233-90=143, atomic number =92-38=54
W=electron e-, on left hand side, total n=7-3+1=5, p=3, 2He4 have 4n and 4p, so one n decay into p+e-