Nuclear Physics Flashcards
Alpha particles -
2 He 4
Charge = 2 * 1.6* 10^-19
Mass = 4 * 1.67 * 10^-27
Discovery of nucleus -
By Rutherford (Alpha scattering experiment)
Conclusion of Rutherford’s Alpha scattering experiment is:
An atom consists of a +ve nucleus at its center which consists of the entire +ve charge and the mass, which is known as nucleus.
Size of atom and size of nucleus are in the order of ?
Size of atom - 10^-10 m
Size of nucleus - 10^-15 m
What is impact parameter?
The perpendicular distance between the center of approaching alpha particle and the center of the nucleus is impact parameter.
What is distance of closest approach?
The minimum distance between the center of the nucleus and the center of the approaching alpha - particle where kinetic energy of alpha particles reduces to zero and is repelled by the nucleus in the backward direction i.e. deflected by 180° is the distance of closest approach.
Mass of nucleus is calculated by -
Mass of nucleus = Zmp + (A-Z)mn
Z = Atomic Number
A = Mass Number
Formula for the size of nucleus is :
R = Ro A ^1/3
Where,
Ro = 1.2 * 10^-15 m OR 1.2 fm
A = Mass number
R = Radius of nucleus
The density of all nucleus is approx. :
2.21 * 10^17 kg/m^3
What are Isotopes?
Those nuclei which have same atomic number but different atomic mass are isotopes.
What are Isobars?
Those nuclei having same atomic mass but different different atomic number are isobars. Example :
6 C 12 and 7 N 14
What are isotones?
Those nuclei having same number of neutrons are isotones. Example :
11 Na 23 and 12 Mg 24
What is atomic mass? (Not same as mass number)
The mass of neutral atom which includes mass of protons neutrons and mass of orbit electrons is atomic mass.
Mass of proton, neutron and electrons are?
Proton - 1.672622 * 10^-27 kg
Neutron - 1.674927 * 10^-27 kg
1ev =? J
1 ev = 1.6 * 10^-19 J
1 Mev = 1.6 * 10^-13 J
1 amu = ? Mev
1 amu = 931 Mev
Why is the mass sum of nucleons is greater than mass of nucleus?
- Some energy is released during formation of the nucleus and the mass decreases.
What is binding energy?
The amount of energy released during formation of nucleus is BE or the amount of energy required to break up the nucleus into its constituents is BE.
If mass defect is in amu, then
BE = Δm * 931 ( In Mev )
If mass defect is in kilograms, then
BE = Δm * c^2
What meaning does B.E./A give?
B.E./A gives amount of energy needed to remove a nucleon from its nucleus.
What is nuclear reaction?
A reaction that involves the change in the nucleus of one element into the nuclei of other elements is known as nuclear reaction.
What is Q-value of a reaction?
The energy released or absorbed during a nuclear reaction is Q-value of the reaction.
If Q value of +ve -
If Q value of -ve -
Exothermic
Endothermic
Q value is
( Mr -Mp ) * 931 Mev
