1. The document discusses nuclear chemistry concepts including nuclear stability factors, mass defect vs binding energy, nuclear reactions such as fission and fusion, and atomic bombs.
2. It provides examples of calculating binding energy and discusses the difference between mass defect and binding energy. Mass defect represents the mass of energy binding nuclei while binding energy is the energy required to split a nucleus.
3. Nuclear fission is described as the splitting of atomic nuclei when bombarded by neutrons or other particles, releasing energy. Uranium-235 and plutonium-239 undergo fission, splitting into smaller nuclei along with neutron release. Neutrons are ideal for inducing fission since they have no charge.
Nuclear physics is a branch of physics that focuses on the study of atomic nuclei and their interactions. It explores the properties and behavior of atomic nuclei, which are the central cores of atoms containing protons and neutrons. This field is crucial for understanding the fundamental forces that govern the behavior of matter at the atomic and subatomic levels.
Nuclear physics is a branch of physics that focuses on the study of atomic nuclei and their interactions. It explores the properties and behavior of atomic nuclei, which are the central cores of atoms containing protons and neutrons. This field is crucial for understanding the fundamental forces that govern the behavior of matter at the atomic and subatomic levels.
Types Of nuclear reactions. Nuclear Fission Reaction. Nuclear Fusion Reaction. Difference between nuclear fusion and nuclear fusion. Light Element Fission. Light Element Fusion. Nuclear Fusion on Sun. Beta Decay process happening in sun. A short explanation of D–D reaction, D–He(3) reaction, D–T reaction. the outstanding problem is the tritium supply. Binding energy curve.Energy partition in process of fusion reactions. How then can light element fusion reactions be initiated? A major explanation for all these above steps. A complete explanation by Syed Hammad Ali Gillani.
In 1909, Rutherford performed the Gold Foil Experiment and suggested the following characteristics of the atom:
It consists of a small core, or nucleus, that contains most of the mass of the atom
This nucleus is made up of particles called protons, which have a positive charge
The protons are surrounded by negatively charged electrons, but most of the atom is actually empty space.
In 1913, Bohor proposed the Atomic Model, which suggests that electrons travel around the nucleus of an atom in orbits or definite paths.
Atom consists of a tiny nucleus.
Each orbit has fixed energy that is quantatized.
The energy is emitted or absorb only when an electron jumps from one orbit to another.
Electron can revolve in orbits of fixed angular momentum mvr.
Liquid Drop Model
The nuclei of all elements are considered to be behave like a liquid drop of incompressible liquid of very high density.
In an equilibrium state the nuclei of atoms remain spherically symmetric under the action of strong attractive nuclear forces just like the drop of a liquid which is spherical due to surface tension.
The density of a nucleus is independent of its
size just like the density of liquid which is also
independent of its size.
The protons and neutrons of the nucleus move about
within a spherical enclosure called the nuclear
potential barrier just like the movement of the
molecules of a liquid within a spherical drop of liquid.
. The binding energy per nucleon of a nucleus is constant
Binding Energy
The binding energy, BE, of a nucleus is a measure of the strong force and represents the energy required to separate the nucleus into its constituents protons and neutrons;
Greater the binding energy, the more stable the nucleus.
Volume
The volume of the nucleus is directly proportional to the total number of nucleons present in it.
Density
The density of the nucleus is nearly constant.
Introduction to Class 12 Physics - Nuclei:
In the realm of physics, the study of atomic nuclei constitutes a pivotal and intriguing segment, forming the nucleus of Class 12 Physics. Delving into the heart of matter, this section unravels the intricacies of the atomic nucleus, where protons and neutrons converge to define the essence of elements. From the formidable forces that bind these particles to the dynamic processes of radioactive decay, Class 12 Physics - Nuclei unveils the mysteries that govern the core of our physical reality.
As students embark on this journey, they will explore the minuscule dimensions of the nucleus, grapple with the potent forces that operate within, and unravel the applications that extend from nuclear power generation to medical diagnostics. The study of nuclei encapsulates the very essence of matter and energy, offering profound insights into the fundamental nature of the universe.
Through an exploration of nuclear reactions, radioactivity, and the applications that span from energy production to medical advancements, Class 12 Physics - Nuclei equips students with a comprehensive understanding of the microscopic world that shapes the macroscopic reality we inhabit. The journey into the heart of the atom awaits, promising a voyage into the fundamental building blocks that define the physical universe.
For more updates, visit- www.vavaclasses.com
Types Of nuclear reactions. Nuclear Fission Reaction. Nuclear Fusion Reaction. Difference between nuclear fusion and nuclear fusion. Light Element Fission. Light Element Fusion. Nuclear Fusion on Sun. Beta Decay process happening in sun. A short explanation of D–D reaction, D–He(3) reaction, D–T reaction. the outstanding problem is the tritium supply. Binding energy curve.Energy partition in process of fusion reactions. How then can light element fusion reactions be initiated? A major explanation for all these above steps. A complete explanation by Syed Hammad Ali Gillani.
In 1909, Rutherford performed the Gold Foil Experiment and suggested the following characteristics of the atom:
It consists of a small core, or nucleus, that contains most of the mass of the atom
This nucleus is made up of particles called protons, which have a positive charge
The protons are surrounded by negatively charged electrons, but most of the atom is actually empty space.
In 1913, Bohor proposed the Atomic Model, which suggests that electrons travel around the nucleus of an atom in orbits or definite paths.
Atom consists of a tiny nucleus.
Each orbit has fixed energy that is quantatized.
The energy is emitted or absorb only when an electron jumps from one orbit to another.
Electron can revolve in orbits of fixed angular momentum mvr.
Liquid Drop Model
The nuclei of all elements are considered to be behave like a liquid drop of incompressible liquid of very high density.
In an equilibrium state the nuclei of atoms remain spherically symmetric under the action of strong attractive nuclear forces just like the drop of a liquid which is spherical due to surface tension.
The density of a nucleus is independent of its
size just like the density of liquid which is also
independent of its size.
The protons and neutrons of the nucleus move about
within a spherical enclosure called the nuclear
potential barrier just like the movement of the
molecules of a liquid within a spherical drop of liquid.
. The binding energy per nucleon of a nucleus is constant
Binding Energy
The binding energy, BE, of a nucleus is a measure of the strong force and represents the energy required to separate the nucleus into its constituents protons and neutrons;
Greater the binding energy, the more stable the nucleus.
Volume
The volume of the nucleus is directly proportional to the total number of nucleons present in it.
Density
The density of the nucleus is nearly constant.
Introduction to Class 12 Physics - Nuclei:
In the realm of physics, the study of atomic nuclei constitutes a pivotal and intriguing segment, forming the nucleus of Class 12 Physics. Delving into the heart of matter, this section unravels the intricacies of the atomic nucleus, where protons and neutrons converge to define the essence of elements. From the formidable forces that bind these particles to the dynamic processes of radioactive decay, Class 12 Physics - Nuclei unveils the mysteries that govern the core of our physical reality.
As students embark on this journey, they will explore the minuscule dimensions of the nucleus, grapple with the potent forces that operate within, and unravel the applications that extend from nuclear power generation to medical diagnostics. The study of nuclei encapsulates the very essence of matter and energy, offering profound insights into the fundamental nature of the universe.
Through an exploration of nuclear reactions, radioactivity, and the applications that span from energy production to medical advancements, Class 12 Physics - Nuclei equips students with a comprehensive understanding of the microscopic world that shapes the macroscopic reality we inhabit. The journey into the heart of the atom awaits, promising a voyage into the fundamental building blocks that define the physical universe.
For more updates, visit- www.vavaclasses.com
Similar to Assignment Physical Chemistry By Anam Fatima (20)
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
The French Revolution Class 9 Study Material pdf free download
Assignment Physical Chemistry By Anam Fatima
1. GC. Women University, Sialkot .
Assignment Nuclear Chemistry
Submitted To, Ma’am Hafsa
Submitted By, Anan Fatima
Roll No. 20
Session 2014-2018
Semester 6th
Department Chemistry
2. Assignment Physical Chemistry
Topic Nuclear chemistry
Answer the following questions
Question no : 1
a. Why certain isotopes are stable while others are radioactive? Discuss various
factors affecting nuclear stability.
Isotopes are atoms with the same number of protons but different number of neutrons.
As, both protons and neutrons are present inside the nucleus. Neutrons being neutral,
minimizes the proton-proton repulsion. If there are too many protons then the repulsive
force overcomes the nuclear force holding them together or if there are too many
neutrons the atom is said to be unstable. Unstable isotopes then undergo radioactive
decay i.e the emission of radiation. In most cases, elements like to have an equal number
of protons and neutrons because this makes them the most stable.
Example:
Carbon has three isotopes with different number of neutrons; , , . Out of
these three isotopes of carbon, C-14 is unstable and radioactive isotope.
FACTORS AFFECTING NUCLEAR STABILITY:
The factors that affect or determine the nuclear stability are
1. Neutron /Proton Ratio:
The N/Z also determines the nuclear stability. Except in the case of ordinary hydrogen ( H),
all other nuclides contain both neutrons and protons. Stable nuclei have N/Z ratio ≥1.the
ratio is ≈ 1 for light nuclides up to Ca and after this the ratio is > 1 for heavy nuclides .
NM/Z ratio in some stable nuclides
�
�
� � � �
Z 1 10 30 40 50
N 1 10 34 50 70
Z/N 1 1 1.15 1.25 1.40
3. As the atomic number increases, the N/Z also increases of stable nuclei. The stable nuclei are
located in an area of the graph nown as band of stability. Since large no. of elements have
several stable isotopes, the curve is in the nature of a strip or zone which widen out at higher Z
values. All stable nuclei fall within this value
Examples:
2. Magic numbers of nucleons:
Nuclei having 2,8,20,27,28,50,82 or 126 protons or neutrons are more abundant in
nature and nuclei with these magic numbers are more stable. If the nuclei have both proton and
neutron number as magic numbers then these nuclei are very stable.
Examples:
�� , , ,
3-Even-odd rule:
It is also known as even-odd nature of protons and neutrons. The 165 nuclides with even number
of protons and even number of neutrons are stable. Just five nuclei, �, �, �, , with
odd numbers of protons and neutrons are stable. Nuclei with even-odd combination are
intermediate stability
Stable nuclei n:p
�� 1:1
� 1.33:1
� 1.4:1
4. Examples:
�� , , � , �� .
b. Explain the difference between mass defect and binding energy?
Nuclear binding energy is the energy required to split a nucleus of an atom into its
components. The more binding energy, the more stable the nucleus will ne.
The mass defect of a nucleus represents the mass of the energy binding the nuclei
and is the difference between the mass of a nucleus and the sum of the masses of the nucleons of
which it is composed. It is calculated as:
∆m = (mp+mn) -mo
Where mp= mass of total protons (mass of 1proton= 1.00728 amu)
mn = mass of total neutrons(mass of 1neutron= 1.00867 amu)
mo = observed atomic mass
Mass defect and Binding energy can be related by the EINSTEIN’S MASS-ENERGY
EQUATION i.e.
∆E = ∆mc2
where ∆m is the mass defect and ∆E is the binding energy. Both these parameters are inter-
convertible. Binding Energies are usually expressed in MeV.
1amu = 931.5 MeV
So, binding energy can be calcaluted as:
∆E = 9γ1.5 ×∆m
c. Calculate the binding energy of �� in MeV per atom if the exact mass of the
nuclide is 6.01512 amu.
5. Data:
Atomic mass of Li = 6.01512 amu
Binding energy of Li /atom = ?
Solution :
As, Mass of protons = 1.00727 amu
and Mass of neutron = 1.00866 amu
In Li, Mass of protons = 3 × 1.00727 amu = 3.02181 amu
Mass of neutron= 3 × 1.00866 amu =3.02598 amu
So, Mass of nucleo = mass of protons + mass of neutrons
= 3.02181 + 3.02598 = 6.04779amu
Mass defect=∆m = mass of nucleon – atomic mass of Li
= 6.04799 – 6.01512
∆m = 0.0γβ67amu
As, 1amu = 931.5MeV
Binding energy =∆E= ∆m × 9γ1.5
= 0.03267 × 931.5
= 30.4 MeV/atom
Question no : 2
1- What is nuclear reactions?
A reaction is the process in which change in the character of a nucleus take place either
spontaneously or as the result of bombardment by a particle or a ray. A nuclear reaction take
place if a particle able to enter a target nucleus. The particle which is used to strike a target
nucleus called projectile.
Or A nuclear reaction is considered to be the process in which two nuclear
particles interact to produce two or more nuclear particles or ˠ-rays (gamma rays). Thus,
a nuclear reaction must cause a transformation of at least one nuclide to another.
6. Types of nuclear reactions 1-Fission 2-Fusion.
● 1-Nuclear fission occurs when larger, heavier atoms are split into smaller atoms. This is
the type of reaction used in nuclear power plants and in most atomic bombs.
• Nuclear fission of U-235
• 2-Nuclear fusion occurs when two smaller atoms are fused together into a larger one. The
sun generates its power through nuclear fusion reactions.
Nuclear fusion of two hydrogen atoms
1- In nuclear reactions, no breaking or making of bonds is involved while they generally
involve breaking of old bonds and formation of new chemical bonds.
2- Generally nuclear reactions proceed with tremendous release of energy whereas chemical
reactions may involve evolution of absorption of energy.
3- Temperature and pressure do not affect the rates of nuclear reactions whereas the rates of
chemical reaction are affected by temperature and pressure conditions.
4- Nuclear reactions are generally irreversible while chemical reactions can be reversible as
well as irreversible.
5- Nuclear reactions involve the conversion of one nuclide into the other and chemical
reactions simply involve the rearrangement of atoms and do not involve any change in
the nucleus.
6- In nuclear reactions, large amount of energy release while in chemical reaction less
amount of energy release.
7- Mass changes are detectable while in chemical reaction. In chemical reactions mass reactants
= mass product
2- What is atomic bomb?
Definition:
Powerful explosive nuclear weapon fueled by the splitting, or fission, of the nuclei of uranium or
plutonium in a chain reaction.
Principle
An atom bomb works on the principle of nuclear chain reaction ( fission ).
7. Fission is the releases process of splitting an atom into many fragments by bombarding it. This
breaking of nuclear bonds a lot of energy in the form of heat and radiation and neutrons are
produce.
Processes
When a single free neutron strikes the nucleus of an atom of radioactive material like uranium or
plutonium, it knocks two or three more neutrons free. Energy is released when those neutrons
split off from the nucleus, and the newly released neutrons strike other uranium or plutonium
nuclei, splitting them in the same way, releasing more energy and more neutrons. This chain
reaction spreads almost instantaneously.
3- What is nuclear fission? Explain nuclear fission with full detail.
Definition:
“A reaction in which an atomic nucleus of a radioactive element splits by bombardment
from an external source with simultaneous release of large amounts of energy, used for electric
power generation”.
Explanation:
Nuclear fission is an exothermic reaction and excess amount of energy is released in
this process. Nuclear fission may also occur spontaneously in the case of very heavy nuclei. A
“chain reaction” results when the neutrons released during fission cause other nearby nuclei to
break apart.
3 n
3 n
3 n
+ E
8. Nuclear fission reactions can be controllable. Nuclear reactor uses controlled chain
reactions to generate electricity. But, uncontrolled fission chain reactions take place during the
explosion of an atomic bomb.
Example of nuclear fission:
Uranium-235 and Plutonium-239 are two fissionable substances undergoing nuclear
fission reaction. For fission to occur in the Uranium -235 nucleus, it first absorb a neutron.
Then, the nuclei The nucleus undergoing fission splits into smaller nuclei . Barium-141 and
krypton-92 are just two of many possible products of this fission reaction and 2-3 neutrons and
energy is released .These neutrons may go on to start a chain reaction.
U + n Ba + K r + n
4- Why neutrons are the ideal bullets for fission reaction?
Due to the neutrality of neutron particles, they are the ideal bullets for fission reaction.
Neutrons are the ideal bullets for fission reaction because they are neutral particles. As the
nucleus is composed of proton and neutron and is positively charged, repulsion forces are
stronger when the positively charged nucleus is being strike by particle other than neutron like
proton that is also positively charged particle. While neutrons have no charge so, don’t cause
such type of problem.
Question no : 3
a) What is decay constant and half-life? How are these interrelated?
DECAY CONSTANT:
Definition:
The decay constant is the fraction of the number of atoms that decay in 1 second. It is the
probability of decay per unit time. It is also known as “disintegration constant”.
Representation:
It is represented by symbol λ.
Formula:
λ = -N
��
��
Where dN/dt = number of decays per second / Activity
N = number of atoms
9. Unit:
s-1
is the unit of decay constant.
HALF-LIFE:
Definition:
Half-life is a measure of the tendency of the half of the nucleus to "decay" or "disintegrate". It
can also be defined as the time needed to convert half of a reactant into the product.
Representation:
It is represented by t1/2 if the t is the total time to decay whole nucleus.
Formula:
t / =
.
λ
Units:
sec or min are the units of half-life.
RELATIONSHIP BETWEEN HALF-LIFE AND DECAY CONSTANT:
The rate of radioactive decay is typically expressed in terms of either the radioactive half-life, or
the radioactive decay constant. They are related as follows:
Suppose at time “t” , the initial concentration of radioactive element is N0
According to decay’s law:
λ =
.
t
log
N
N
By definition, if time t = t1/2 then N =
N
Put the values in above equation,
λ =
.
t /
log
N
N ⁄
λ =
.
t /
log
λ =
. × .
t /
10. λ =
.
t /
So, the above expression shows the inverse relation of half-life and decay constant.
b) How do half-life and decay constant determine experimentally ?
Half-life and decay constant can be experimentally determined by the device
“Geiger-Muller Counter”. One of the first devices used to detect radioactivity was a Geiger-
Muller tube, which is a gas filled cylinder with a very thin metal wire down its center. A voltage
difference is maintained between the center wire and the cylinder. If radiation interacts with the
gas in the cylinder, ionization of the gas atoms takes place. Because of the voltage difference, the
electrons move toward the center wire and the positive ions move toward the outer cylinder. This
is an electrical discharge producing a pulse of current which can be counted. Each pulse indicates
that a nucleus has decayed and the decay rate or decay constant is measured by the number of
pulses per second.
Before the source is used the background, count rate is measured using a Geiger Muller
tube connected to a counter. The count rate from the source is then measured at regular fixed
intervals over a time period. The background count rate is then subtracted from each
measurement and the actual count rate from the source is measured. A graph of the count rate of
the source against time is plotted. From the graph, the time taken for the count rate to fall by half
is measured. A number of measurements are made and an average value is calculated. The
average value is the half-life of the radioactive source.
c) The half-life of � is 14.3 days. How long it would take for 1g of sample of
� to decay to 0.5g of?
DATA:
11. t1//2 = 14.3days
[N0] = 1g
[N] = 0.5g
t = ?
Solution :
As t1//2 =
.
λ
λ =
.
t /
=
.
.
= 0.0484 /days
t =
.
λ
log
[No]
[N]
=
.
.
log
.
= 47.58 × log 2
= 47.58 × 0.301
= 14.3 days
d) Calculate the half -life of decay of ��
�
if ig of sample decays to 0.125g in
165min.
DATA:
t = 165min
[N0] = 1g
[N] = 0.125g
t1/2 = ?
Solution:
12. As, λ =
.
t
log
[No]
[N]
=
.
log
.
= 0.0139 × log 8
= 0.0139 × 0.903
= 0.0125 /min
t1//2 =
.
λ
=
.
.
= 55.4 min
Question no :4
Comment on the following statements.
1) The future of mankind is in the hands of nuclear scientists.
The nuclear chemistry has become a very important branch of science due to tremendous amount
of energy that liberated during nuclear reactions. The study indicates that most of the prosperous
nations are extracting about 30-40 per cent of power from nuclear -power and it constitutes a
significant part of their clean energy case. It reduces the burden of combating climate change and
the health hazards associated with pollution. But, nuclear scientists can destroy the whole world
into few seconds. The radioactive wastes coming from nuclear power plants, atomic bomb, chain
reaction, all these things are very dangerous for human beings. In addition, Nuclear weapons are
the most powerful and destructive fighting tools the world has ever known. So, it is rightly said
that future of mankind is in the hand of nuclear scientist.
2) Curie is the SI unit of radioactivity.
The older unit for measuring the amount of radioactivity was the Curie that’s was named after
Pierre and Marie Curie. It is the activity of 1 gram of radium isotope Ra. It is represented by
Ci and is defined as:
1 Curie = 3.7x1010
decays per second
13. The curie has been replaced by the SI unit Becquerel after Henri Becquerel. It is defined as
the activity of a quantity of radioactive material in which one nucleus decays per second.it is
represented by Bq.
1 Bq = 1 s−1
The relationship between Curie and Becquerel are given as:
Bq = 2.703x10-11
Ci
Ci = 3.7×1010
Bq
3) Lighter nuclides have more binding energy.
As, Nuclear binding energy is the energy required to split a nucleus of an atom into its
components. More the binding energy, the harder it to split the nuclide and more stable it will be.
There are stronger nuclear forces (short-range attractive) in the lighter nuclides. As the atomic
number (Z) increases, the repulsive electrostatic forces (proton-proton repulsion forces) within
the nucleus increase. To overcome this increased repulsion and maintain stability, the proportion
of neutrons in the nucleus must increase. As the repulsive forces are increasing, less energy must
be supplied to remove a nucleon from the nucleus. In other words, the Binding energy per atom
has decreased.
The above graph shows that as the atomic mass number increases, the binding energy per
nucleon decreases for mass no. > 60. The BE/A curve reaches a maximum value of 8.79 MeV at
A= 56 and decreases to about 7.6 MeV for A = 238. The increase in the Binding energy per
nuclide as the atomic mass number decreases from 260 to 60 is the primary reason for the energy
liberation in the fission process. In addition, the increase in the BE/A as the atomic mass number
increases from 1 to 60 is the reason for the energy liberation in the fusion process, which is the
opposite reaction of fission.
14. 4) Radionuclides are intrinsically unstable.
A radionuclide is an atom that has excess nuclear energy, making it unstable. This excess energy
can be either emitted from the nucleus as gamma radiation, or create and emit from the nucleus a
new particle (α or particle), or transfer this excess energy to one of its electrons, causing that
electron to be ejected as a conversion electron. During those processes, the radionuclide is said to
undergo radioactive decay. These emissions constitute ionizing radiation. The unstable nucleus is
more stable following the emission, but will sometimes undergo further decay. All the nuclides
with atomic number greater than 83 are radioactive and are beyond the band of stability.
EXAMPLES:
Examples of α-decay of radionuclides are given as:
U Th +
Po Pb +
5) All radioactive decay follows first-under kinetics.
Radioactive decay is the emission of a particle that results from the spontaneous decomposition
of the unstable nucleus of an atom. A radioactive decay is a first-order process and can be
described in terms of the rate law as:
−
ΔN
Δt
= k N
In radioactive decay, the number of radioactive atoms decaying per unit time is proportional to
the total number of radioactive atoms present at that time. Since the decay rate is proportional to
first power of radioactive atoms present, therefore, radioactive decay is a first order kinetics. As,
radioactive decay is a first-order process, the time required for half of the nuclei in any sample of
a radioactive isotope to decay is a constant, called the half-life of the radioactive nuclides.
6) Nuclear fission is a sustainable reaction.
Nuclear fission technology is the only developed energy source that is capable of delivering the
enormous quantities of energy that will be needed to run modern industrial societies.
Nuclear Fission reaction generates a large amount of nuclear energy and this is sustainable
because it meets all the criteria of sustainability. Fission can be self-sustaining because it
produces more neutrons with the speed required to cause new fissions. Today's commercial
uranium-fueled nuclear power plants can provide the world with clean, economical and reliable
energy well into the next century on the basis of the already-identified uranium deposits.
7) Water is used as moderator in atomic pile.
15. Nuclear reactor is formerly known as atomic pile. Light and heavy water can have dual function.
They can act as both moderator and coolant in nuclear reactor. These moderators slows the fast
(high-energy) neutrons emitted during fission to energies at which they are more likely to induce
fission. In doing so, the moderator helps initiate and sustain a fission chain reaction.
Most commercial nuclear reactors use normal water (also called light water) as a neutron
moderator. Some reactor designs, such as the CANDU reactor, use heavy water. Heavy water is
made from deuterium instead of hydrogen + normal oxygen. Deuterium is much less likely to
absorb neutrons than proton. As a result, heavy water increases the probability of fission with the
fuel material.
8) α –particles have more penetrating power.
This statement is not correct. α –particles have least penetrating power they are stopped by the
sheet of paper or thin Al foil. They are heavier than beta and gamma particles and can be easily
stopped by a few sheets of paper, so have least penetrating power. Beta particles are more
penetrating, but still easily shielded. Gamma rays have greatest penetrating and are the most
difficult to stop and require concrete, lead, or other heavy shielding to block them. So, the
decreasing order of penetration power of radiations is:
-rays > -rays > α –rays
9) β –particle have more ionizing power.
Ionizing power is the ease with which ionizing radiation forms ions. It is directly related to
kinetic energy. -particles have speeds of up to 18 times greater than alpha particles, with a
mass of 7400 times less than alpha particles, the kinetic energies of beta particles are much less
16. than those of α- particles thus has a lower ionizing power than alpha bur more than -rays.
Therefore, the above given statement is incorrect.
The decreasing order of ionizing power of radiations is:
α-rays > -rays > –rays
10) Radiations can damage human skin.
Radiation exposure greater than certain limit, can damage the human body. By the radiations,
rapidly dividing skin cells can be damaged, leading to skin lesions. Acute exposure of radiations
can cause skin redness and burns. and –radiations are the most dangerous radiation sources
because they can penetrate the skin and damage the cells inside. α-particles are the least
dangerous in terms of external exposure because they don't penetrate very deeply into the skin, in
fact, clothing can stop α- particles.
11) Radiations can be used for diagnostic purposes.
There are nearly one hundred radioisotopes whose and –radiation radiations are used in
diagnosis, therapy, or investigations in nuclear medicine. Some of the uses of radiations for
diagnosis are:
❖ Radiotherapy can be used to treat some medical conditions, especially cancer, using
radiation to weaken or destroy particular targeted cells.
❖ Radiation to provide information about the functioning of a person's specific organs or to
treat disease.
❖ In hospitals, ionizing radiations are used for tests in the form of X-ray include:
❖ Radiographs - commonly, known as x-rays.
❖ CT scans - used to be called CAT scans.
❖ Radioactive 131
I, with a half-life of 8 days, is used to diagnose and treat thyroid disorders.
12) Atomic bomb uses nuclear fission reaction.
Atomic bombs are nuclear weapons that use the energetic output of nuclear fission to produce
massive explosions. Atomic bombs are made up of a fissile element, such as uranium. Fission
was much more likely to occur in the uranium-235 isotope. Fission occurs when a neutron strikes
the nucleus of uranium-235 isotope, splitting the nucleus into fragments known as fission
fragments and releasing three new neutrons and tremendous amount of energy. The fission
process becomes self-sustaining as neutrons produced by the splitting of atom strike nearby
nuclei and produce more fission. This is known as a chain reaction and it causes an atomic
explosion.
+ � → � + �� + 2 neutrons + 180MeV
17. 13) H-bomb works on the principle of nuclear fusion.
The hydrogen bomb is a nuclear weapon that uses a mixture of fission and fusion to
produce a massive explosion. It has two cores. One is a classical atomic bomb called primary.
The other core, the secondary is a combination of deuterium, hydrogen, lithium and uranium.
They are mounted inside an x-ray, gamma ray reflecting material. The energy released by the
primary section compresses the secondary through a process called "radiation implosion," at
which point it is heated and undergoes nuclear fusion.
The nuclear fusion releases neutrons much faster than a fission reaction, and these
neutrons then bombard the remaining fissile fuel, causing it to undergo fission much more
rapidly. So, most of the energy comes from fission and fusion only enhances neutron production
contributing little to the explosion.
14) Radiation dosimeters are used to measure the amount of radiation
damaged.
Radiation damage Includes ionizing radiations such as α, , and - rays; X rays; and
protons, neutrons, and other particles. Radiation dosimetry is the calculation and assessment of
the ionizing radiation dose received by the human body due to both external irradiation and the
ingestion or inhalation of radioactive materials. Dose is used to describe the amount of energy
absorbed per unit mass at a site of interest. The SI unit for dose is the gray, Gy: 1 Gy = 1 J/kg =
100 rad. Internal dose is calculated from a variety of physiological techniques, whilst external
dose is measured with a dosimeter or inferred from other radiological protection instruments.
15) Heavy nuclides usually decay by β-decay.
This statement is not true. Heavy nuclides usually decay by α-decay not -decay.
Beta decay can occur in nuclei that are rich in neutrons - that is - the nuclide contains more
neutrons than stable isotopes of the same element. In order to regain some stability, such a
nucleus can decay by converting one of its extra neutrons into a proton, emitting an electron and
an anti-neutrino(ν). The high energy electron emitted in this reaction known as beta particle.
Lighter atoms (Z < 60) are the most likely to undergo -decay.
EXAMPLES:
Na Mg + e
−
+ v
C N + e
−
+ v