Nuclear Structure And Radioactivity.

Atomic mass unit ( unified atomic mass unit (u)):-

The the masses of atom, nuclei and fundamental particles such as electron ,proton and neutron are expressed in unified atomic mass unit (u).
One u is defined as 1/12th of the mass of 6CĀ¹Ā² atom. The masses of other atoms are determined by measuring the positions of the lines they produce in a mass spectrograph related to that of 6CĀ¹Ā² atom.
[6CĀ¹Ā² carbon atom is stable and 6CĀ¹ā“ is Radioactive used for carbon dating]
1u = 1/12 *[mass of 1 6CĀ¹Ā² atom]
1u = 1.6605 Ɨ10^(-27) kg
Following are the masses of the common particles and atom in terms of unified atomic mass unit (u):-
  • Election(eā») = 0.0005486 u
  • Proton = 1.007276u
  • Ī±-particle = 4.001506u
  • He atom = 4.002603u

Nuclear Size:-

According to Rutherford the side of atomic nucleus is 10^(-15) m.
The volume of a nucleus is directly proportional to the number of nucleons in it which is its mass number (A).
VolumeāˆA
ā“ā„ā‚ƒĻ€RĀ³ āˆ A
RĀ³āˆ A
R āˆ Aā…“
R=RĀ°Aā…“
Where RĀ° is an empirical constant whose value is experimentally found to be roughly 1.2 into 10^(-15) m.
RĀ°=1.2Ɨ10^(-15) m
The mass number 'A' is different for different atoms. Nuclei of different atoms have different radii , it's SI unit is 'Fermi'(F).
1 Fermi(F) = 10^(-15) m
R=RĀ°Aā…“
R=1.2 Ɨ 10^(-15) Ɨ Aā…“

R=1.2Aā…“ Fermi


Energy energy equivalent to '1u':-

According to Einstein the energy equivalent of mass āˆ†M is given by
āˆ†E = [āˆ†m]cĀ²
where , āˆ†m = 1u
                     =1.6605Ɨ10(-27)Kg
                c = 2.9979Ɨ10^(8) m/s
Then according to the above result
āˆ†E=1.4924Ɨ10^(-10)J
āˆ†E=931.5 MeV
[MeV= million electron volts].

Typed by -  Saransh Agarwal (Tech N Moe)