Question
Explain the phenomenon of nuclear fission.
✓
Answer
$\rightarrow$ When a heavy nucleus is bombarded with a neutron, then first neutron is absorbed.
This nucleus is in a highly excited state. As a result, it splits into two lighter nuclei of approximately equal mass to become stable.
$\rightarrow$ Neutron is chargeless so it does not have to face coulomb forces.
So neutron is a best projectile.
$\rightarrow$ When a neutron is bombarded on the nucleus of uranium its nucleus breaks into two almost equal parts. Its nuclear reaction is as below :
${ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{56}^{144} B a+{ }_{36}^{89} K r+3\left({ }_0^1 n\right)+ Q$
${ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{51}^{133} S b+{ }_{41}^{99} N b+4\left({ }_0^1 n\right)+ Q$
${ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{54}^{140} Xe +{ }_{38}^{94} S r+2\left({ }_0^1 n\right)+ Q$
$\rightarrow$ The fission fragments are radioactive and by successive emmision of $\beta-$ particles results in the stable nuclei.
$\rightarrow$ During the fission process of uranium the energy released per fission is almost 200 MeV .
$\rightarrow$ Suppose a nucleus with mass number $A =240$ breaks into two fragments each of $A =120$.
$\rightarrow$ Binding energy per nucleon for a nucleus with $A =240$ is $7.6 MeV$ and for a nucleus with
$A =120$ is $8.5 MeV.$
$\rightarrow$ Gain in binding energy per nucleon
$=8.5-7.6$
$=0.9 MeV$
$\rightarrow$ Total gain in binding energy
$=0.9 \times 240$
$=216 MeV .$
$\rightarrow$ The disintegration energy in fission events first appears as the kinetic energy of the fragments and neutrons. Eventually it is transferred to the surrounding matter appearing as heat.
$\rightarrow $ In a nuclear reactor this process takes place in a controlled manner whereas in an atomic bomb this process takes place in an uncontrolled manner.
This nucleus is in a highly excited state. As a result, it splits into two lighter nuclei of approximately equal mass to become stable.
$\rightarrow$ Neutron is chargeless so it does not have to face coulomb forces.
So neutron is a best projectile.
$\rightarrow$ When a neutron is bombarded on the nucleus of uranium its nucleus breaks into two almost equal parts. Its nuclear reaction is as below :
${ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{56}^{144} B a+{ }_{36}^{89} K r+3\left({ }_0^1 n\right)+ Q$
${ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{51}^{133} S b+{ }_{41}^{99} N b+4\left({ }_0^1 n\right)+ Q$
${ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{92}^{236} U \rightarrow{ }_{54}^{140} Xe +{ }_{38}^{94} S r+2\left({ }_0^1 n\right)+ Q$
$\rightarrow$ The fission fragments are radioactive and by successive emmision of $\beta-$ particles results in the stable nuclei.
$\rightarrow$ During the fission process of uranium the energy released per fission is almost 200 MeV .
$\rightarrow$ Suppose a nucleus with mass number $A =240$ breaks into two fragments each of $A =120$.
$\rightarrow$ Binding energy per nucleon for a nucleus with $A =240$ is $7.6 MeV$ and for a nucleus with
$A =120$ is $8.5 MeV.$
$\rightarrow$ Gain in binding energy per nucleon
$=8.5-7.6$
$=0.9 MeV$
$\rightarrow$ Total gain in binding energy
$=0.9 \times 240$
$=216 MeV .$
$\rightarrow$ The disintegration energy in fission events first appears as the kinetic energy of the fragments and neutrons. Eventually it is transferred to the surrounding matter appearing as heat.
$\rightarrow $ In a nuclear reactor this process takes place in a controlled manner whereas in an atomic bomb this process takes place in an uncontrolled manner.
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