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 Ć10^(-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).
VolumeāA
ā“āāĻRĀ³ ā A
RĀ³ā A
R ā 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°=1.2Ć10^(-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 Ć 10^(-15) Ć Aā
R=1.2Aā Fermi
Energy energy equivalent to '1u':-
According to Einstein the energy equivalent of mass āM is given byāE = [ām]cĀ²
where , ām = 1u
=1.6605Ć10(-27)Kg
c = 2.9979Ć10^(8) m/s
Then according to the above result
āE=1.4924Ć10^(-10)J
āE=931.5 MeV
[MeV= million electron volts].
Typed by - Saransh Agarwal (Tech N Moe)