Download Into the Atom - Structure of the Nucleus, Heavy Nuclei... Original Script and research: Dr. Arvind Dubey

Into the Atom - Structure of the Nucleus, Heavy Nuclei and Radioactivity
Original Script and research: Dr. Arvind Dubey
Translation: Dr. Sukanya Datta
Characters
Mr Atom
Siddhant:
A boy, 13-14 years old, student of Class 9
Prerna:
Young girl, 17-18 years old, BSc student
Ma:
Mother of Siddhanta and Prerna, Homemaker
Papa:
Father of Siddhant and Prerna, Professor of Physics
Dr. Prabhat:
Radiologist and Dad’s friend
Frederick Soddy
A Radiochemist
Dr. Margaret Todd
A Medical Doctor and Writer
Henri Becquerel
A Physicist
Male voice
(Signature tune)
(Fades out)
(Title song)
(Fades out)
A Male voice: I am an atom. Stable protons and electrons appeared one second after the Big
Bang which occurred approximately 13.7 billion years ago. During the following three
minutes most of the helium, lithium, and deuterium are produced in the universe, and perhaps
some of the beryllium and boron. My first ancestor, complete with bound electrons was created
380,000 years after the Big Bang, when the expanding universe cooled enough to allow electrons
to become attached to nuclei. After this few of our ancestral nuclei were combined
in stars through the process of nuclear fusion to produce more of the element helium, and the
sequence of elements from carbon up to iron. Almost all the atoms present on Earth today were
present in the nebula from which your solar system was created. Some of my present
companions were not around at that point in time. They came into being from the cosmic
radiation such as Cabon14. Some com[anion of mine are artificially generated either deliberately
or as by-products of nuclear reactors or explosions. Of the elements having atomic numbers
greater than 92, only plutonium and neptunium occur naturally on Earth. That’s just how unique
I am. You may have heard a lot about me. People in ancient India, began their efforts to learn
about me as early as the fourth or fifth century. The ancient Greek philosophers hailed me using
the name Atomos meaning indivisible or un-cuttable. However, these were all conjectures. The
first person who tried to understand my nature using the principles of science was John Dalton.
His efforts unleashed a flood of scientific activity dedicated to understanding my nature. Jean
Baptiste Perrin concerned himself with my weight and dimensions. Then, scientists such as
Thomson, Rutherford and Bohr tried to define me in their own way. Scientists laid to rest the
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wrong notion that I was indivisible; that I could not be broken. Then they began to study me and
my components: the sub atomic particles.
If Thomson began his quest for electrons, Rutherford focussed on my central part: the nucleus.
Today, they have identified so many sub-atomic particles that even I have trouble remembering
all the names. Yet, I desire that you should meet this family of mine. If you want to meet me and
members of my family, then come...follow me.
Scene-1
Time: Late night.
Locale- Siddhant’s bedroom.
(Scene Opening music-------------------------------------------------------------------------------------Fades out)
(Siddhant is getting ready for bed)
Siddhant: It’s Ten PM, my bed time.
(Ma enters the room)
Ma: Have you finished your milk, Siddhant?
Siddhant: Yes, Ma.
Ma: Well, then go to sleep. You have to go early to school tomorrow, don’t you?
Siddhant: Yes Ma....Good night Ma.
(Sound effects, signifying it is night)
Atom’s voice (male): Siddhant.
Siddhant: Who...who are you?
Voice: I am Atom.
Siddhant (Mocking tone): Really? So Mr. Atom, what can I do for you?
Atom: Siddhant, do you know what an atom is?
Siddhant: Yes of course. It is the smallest component of an element. It does not exist in free
state but takes part in chemical reactions.
Atom: Correct, but not fully so.
Siddhant (interrupting): Why…. Where I am wrong?
Atom: You see, I am not the smallest component of any element. Scientists have been able to
split me into even tinier components.
Siddhant: I know all that...you mean Electrons, Protons and Neutrons.
Atom: You are a smart boy...how old are you?
Siddhant: 13 years (Proudly) and studying in Class 9.
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Atom: oho!
Siddhant: And my dad teaches Physics in a college.
Atom: If that is so, then you might know that scientists have found even smaller particles than
the ones you have named. Do you know their names?
Siddhant: sorry, I don’t?
Atom: These are called sub-atomic particles.
Siddhant: Sub atomic particles?
Atom: Yes, would you like to meet the members of my family; the sub- atomic particles?
Siddhant (In excited tone): s. Yes...yes...but how?
Atom: I’ll help you...come…….come on...move forward……don’t fear……come (in hypnotizing
tones much like that of a magician), close your eyes...come on...keep going...now open your eyes.
Look.
Siddhant: Oh! What is this? Looks like a point shining through a cloud of haze.
Atom: That’s me...it’s me...the Atom.
Siddhant: What! This is atom? You don’t match the picture in my book.
Atom: Oh really!
Siddhant: Yes, it shows a central circle full of Neutron and protons alongwith electrons studded
in round orbits around it.
Atom (Laughing): ...hey, that’s just a model made by scientists to help you understand the
structure of an atom...it is just a line diagram.
Siddhant: Line diagram?
Atom: Yes a two-dimensional representation... showing just width and height but no thickness.
Siddhant: So?
Atom: Well in reality stuff is three-dimensional, isn’t it? It has width and thickness too.
Siddhant: But your appearance is a little weird... I think there is something inside the circular
hazy thing.
Atom: Absolutely correct. The nucleus is in the centre of the hazy electron cloud.
Siddhant: Electron cloud…….Like rain clouds on Earth?
Atom: No my child, these are not like the rain clouds on Earth; these are super fast electrons
that look like hazy clouds because they are whizzing so fast.
Siddhant: Mmm, you are sharing quite a lot of inside information.
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Atom: Inside...reminds me...so, are you going to step in or are you going to stand outside all the
time? Won’t you come in? Meet the particles that make me up?
Siddhant: Come in? But how?
Atom: You will have to cross my electron cloud...I’ll try and stop the electrons from bumping into
you...come on now...come on, in.
(Music reaches a crescendo and fades)
Si: Ok, here I come.
(Siddhant is breathing noisily which denotes that the
journey through the electron cloud was a difficult one.)
Siddhant (Huffing a little): Well, here I am...how difficult it was to cross the electrons.
Atom: You mean electron cloud. It is just as difficult for the particles to do the same.
Siddhant: Does that mean I have reached the nucleus now?
Atom: Yes indeed. Do you know that almost all my mass resides here; in the nucleus. And this
nucleus is the source of all my energy: you know nuclear energy as you call it.
Siddhant: So the nucleus is the most significant or the most crucial part of your being?
Atom: It is best to call it the densest part of me. Do you know why this is so?
Siddhant: I know Protons and Neutrons reside in the nucleus. Protons are positively charged but
neutrons are neutral…..bear no charge.
Atom: Hmm right. But can I tell you another inside fact?
Siddhant (Surprised): What?
Atom: Neutrons may be neutral but they bear both a positive and a negative charge.
Siddhant (Surprised): What!
Atom: Yes, the central part of a neutron bears positive charge and around it swirls the negative
charge in such a way that both cancel each others.
Siddhant (Interrupting):...and this is why the Neutron does not bear a charge!
Atom: However, as compared to my entire size, my nucleus is still pretty small...say if an atom is
the size of a football, the nucleus will be smaller than the size of a dust particle.
Siddhant (Amazed): Really!
Atom: Well, if you divide the Hydrogen atom into 1.5 lakh units, its nucleus will only be as big as
one such unit.
Siddhant: As far I recollect positively charged particles normally repel each other. Yet here,
inside the nucleus the positively charged protons seem to be happily co-existing side by side.
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Atom: This is because of a strong nuclear forces, some of my sub-atomic particles are
responsible for these nuclear forces.
Siddant: ……….sub atomic particles, which one?
Atom: Yes …..There are many but the strong nuclear force which keeps these protons or
neutrons together inside the nucleus is because of gluons.
Siddhant: Gluons?
Atom: Yes Gluons. These are mass-less particles with no shape either. It is simply experienced as
a force, so to say.
Siddhant: Wow!
Atom: And you will be amazed to know that my entire mass is because of my Protons and the
Neutrons.
Siddhant: But what about the Electrons?
Atom (Dismissively): Forget Electrons, they have negligible mass anyway...all they do is whizz
around, all action, no mass.
Siddhant: Action? What sort of action?
Atom: Well, suppose I lose an electron or even if I gain an electron then I am no longer an atom.
Then I become an Ion.
Sid: Ion?
Atom: See if I gain an electron I gain an extra negative charge so becomes a negative ion. If I lose
an electron I lose a negative charge and become a positively charged atom or positive ion.
Siddhant: And these are ions that take part in chemical reactions.
Atom: Exactly……. would you like to meet my miniscule teeny-tiny subatomic particles?
Siddhant: Mr Atom, I think I will take you up on your offer some other time.
Atom: That means you will go back now... then you have to go the same way that you came in.
Siddhant: that means I must go through the electron cloud again…….. No! (Shouts) Nooooooooo.
(Scene Change music)
Scene-2
Time: Early morning
Locale- Siddhant’s bedroom.
(Scene Opening music-------------------------------------------------------------------------------------Fades out)
(Siddhant’s parents have reacted to his screams and are now in his room)
Ma (Woried tone): Siddhant...Siddhant...What’s wrong? Are you Ok? Is everything all right?
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Papa: I don’t think anything is wrong; let me take a look.
Siddhant: Mummy...I was in a...an electron cloud....what………but…….you……..where is Mr.
atom………….so it was a dream.
Papa: So you were dreaming, I think.
Ma: ……….he Was scared while dreaming...must have dreamt something fearsome.
Siddhant: Papa, I was trapped in an electron cloud.
Papa: Electron cloud? so there you are……….vow! what a progress….Your father has been
teaching Physics all his life and got nowhere and you, his son went on a trip to electron
cloud……what a move my boy……. Well done indeed. (Laughs)
Ma: All this is because he reads all sorts of books about ghouls and demons and watches all sorts
of programmes on TV...what else do you expect when all such scary ideas flood his mind.
Papa: No, no, our son has actually had a dream about Physics; the subject I teach in college.
Ma (Pretending to be angry):. Go on now, both of you, Scared me like anything! Like father like
son.
Siddhant: It was a strange dream...there was this voice saying, I am an Atom...the voice took me
on a voyage inside an atom...I went past through the electron cloud. The voice introduced me to
all the sub-atomic particles too.
Papa: That’s great, so which particles did you get to meet?
Siddhant: You know...the good old Electrons, Protons and Neutrons.
Papa: That is good, but by now many sub atomic particles have been discovered and a brand
new branch of Physics has been established to study these.
Siddhant: Is that so, Papa.
Papa: yes, this branch has been named Particle Physics.
Siddhant: But Papa, my books list just three particles: Electrons, Protons and Neutrons.
Papa: Actually there are two main types of particles in atoms. One which accounts for the mass
of the atom...these are called Fermions.
Siddhant: Fermions? Papa...Fermions?
Papa: Yes Siddhant and the other type is called Boson. These Bosons account for the nuclear
forces.
Siddhant: So the Bosons are the force carrying particles in an atom.
Papa: Yes…….do you know, Bosons are named after a famous Physicist of our country;
Satyendra Nath Bose.
Siddhant: Satyendra Nath Bose?
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Papa: Yes. He laid the conceptual groundwork for the presence of this particle. Later, research
confirmed what he had postulated.
Siddhant: So, we have two types of sub-atomic particles. Fermions and Bosons.
Papa: And Fermions again are of two types……Quarks and Leptons.
Siddhant: The situation is getting rather complicated now. First we had Fermions and Bosons;
now I know that Fermions are of two types Quarks and Leptons...are there others too or is this
all?
Papa: Well, quarks are of six types of and six different types of leptons too.
Siddhant: And what about the Bosons?
Papa: Siddhant, Bosons are also of six types. There are four types of Gauge Bosons which are
responsible for the force-carrying; then you have the graviton which is thought to be the carrier
of the gravitational field and last but not the least the Higgs Bosons.
Siddhant: Higgs Bosons? These were was in the news a few days back, wasn’t it? They called it
the God Particle.
Papa: Yes, the same. A few years back scientists made a gigantic machine called the Large
Hadron Collider and used it to discover Higgs Bosons along with many other.
Siddhant: Ah, so these are the building blocks of the Universe.
Papa: Cannot say so with certainty, but a scientist has made such a claim.
Siddhant: Papa if I summarize: There are two types of particles. Fermions and Bosons. Fermions
are of two types Quarks and Leptons. Right? Quarks are of 6 types and Leptons are also of six
types. Now we have Bosons, which are also of six types. Four types are Gauge Bosons, Graviton
and the God particle the Higgs Boson.
Papa: Excellent.
Siddhant: But Papa, in this crowd of particles where are our familiar electrons, protons and
neutrons? They seem to have got lost.
Papa: Oho...well, the electron is a kind of Lepton.
Siddhant: And what about our neutrons and protons?
Papa: Actually protons and neutrons are made up of tiny constituents too.
Siddhant: Really!
Papa: Yes, this is why these are called Compound particles. These are made up of different types
of quarks.
Siddhant: So if quark particles combine to make protons and neutrons then is it possible to break
protons and electrons to get quarks?
Papa: You have understood correctly.
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Siddhant: Papa, atoms are shaped like a ball, aren’t they?
Papa: Cannot say Siddhant, because of the hazy outline of an electron cloud it is difficult to
determine its exact shape. Because of this it is not possible to determine the exact shape of an
atom.
Siddhant: Anyway atoms are usually not found to exist independently.
Papa: It is conjectured that in.....atoms are spherical and looks like a ball, which is only obeyed
for atoms in vacuum or free space.
Siddhant: Papa, atoms must be really tiny.
Papa: Mmm...let’s see...suppose you place a lakh Carbon atoms side by side, its width would be
less than the width of one of your hairs.
Siddhant: Hah...then, I don’t think it is possible to find out how much an atom weighs.
Papa: Why not? Scientists have figured out ways to do so. The unit of atomic weight is called a
Dalton.
Siddhant: Dalton?
Papa: It is defined as one twelfth of the mass of an unbound neutral atom of carbon.
Siddhant: My books say that the lightest atom is that of Hydrogen.
Papa: That’s right. A hydrogen atom has a mass slightly more than One Dalton. Lead is the
heaviest, its atom weighs about 208 Dalton.
Siddhant: Papa, but in my book Carbon is sometimes represented with capital C and the number
6 is before it in subscript and number 12after this capital C in superscript.
Papa: This is also a way on providing information about atoms. It was Mendeleev who initiated
this system.
Siddhant: Oh!
(Prerna enters. Voice comes closer as she is approaching)
Prerna: What is this Papa, it is Sunday so you don’t go to college but set up a school at home!
Papa: No, no...my dear...it is just that your brother...
Prerna: Huh...you mean to say my brother has suddenly become so studious that instead of
getting out of bed late, he has started taking lessons in bed, that too on Physics...and hey you
Siddhant will the Sun rise in the west today?
Siddhant: Oh no Prerna didi...it is just that I had a strange dream.
Prerna: What...you mean to say you are now studying even in your dreams? You wander whole
day aimlessly to kill time and now you even in your sleep...this is simply great.
Siddhant (shouting): Prerna di.
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Papa (Laughing): Do you know that in his dreams Siddhant entered an atom and was screaming
from there? (Laughs)
Prerna: Well, it is a blessing that he entered an atom and not an atomic reactor or else we would
have got isotopes of Siddhant instead of Siddhant himself.
Siddhant: Stop pulling my leg and by the way what is this Isotope you are talking about?
Prerna: I am in no mood to indulge in academics so early in the morning...Papa is here...he is
good enough for this.
Papa: But where are you going Prerna? I will be having my tea here itself.
(Ma enters the room- give appropriate sound effects of footsteps)
Ma: And here is Ma with piping hot tea..with cardamom and ginger too.
Prerna: Mom you are great..., let me take my cup. (Sounds of cups and saucers and people
sipping tea.) Hey Isotope of Siddhant……… XSiddhant Y plus One........
Siddhant: Ma...look …….this Prerna di.
Ma: Prerna, why are you teasing him?
Prerna: No Ma, I am not...do you know where he went today in his dreams …….Inside an atom!
(Laughs)
Ma: That is why he woke up screaming, No...no...nooooooooo.
Prerna: And that is why he has been transformed into an isotope.
Ma: Isotope?
Prerna: Papa, now explain this to Ma…….dare take this challenge?
Ma: Huh...I have no time for such gossips ... I have so much to do.
(Ma exits, give appropriate sound effects of footsteps)
Siddhant: Papa, you better tell me what an Isotope is...and all this about X and Y plus
One…..Please.
Papa: I will explain. The atomic number is equal to the number of protons in an atom's nucleus.
Siddhant: Atomic number…...?
Papa: Yes.
Prerna: A Carbon atom has 6 protons in its nucleus.
Siddhant: So the atomic number of Carbon is 6, right Papa?
Papa: Absolutely correct.
Prerna: This is written as subscript attached to the left of the symbol of the element.
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Siddhant: So we will write 6 before the symbol C for Carbon.
Prerna (Mockingly): Very intelligent.
Papa: Don’t tease him Prerna. Siddhant, Each atom also has a mass number. The mass number
of an atom is equal to the number of protons plus the number of neutrons that it contains.
Siddhant: Like Carbon has 6 protons and 6 neutrons in its nucleus; so its mass number will be 12.
Prerna: When you write it down, the mass number is written as a superscript on the left of the
element symbol.
Siddhant: So for Carbon we will write 6C12.
Papa: Right. And remember that in any element the number of protons in its nucleus always
remains the same.
Siddhant: If the number of protons always remains the same then the atomic number of an
element will never change.
Prerna. Silly boy; if the atomic number will changes won’t the element’s properties also become
different?
Papa: Correctly said Prerna; but this is not the case with neutrons.
Siddhant: You mean that the number of neutrons in the nucleus of an element can vary?
Papa: It is possible, Yes!
Siddhant: That is so surprising.
Prerna: What’s so surprising about that? If you take Carbon as an example I can tell you that
sometimes the number of neutrons in the nucleus goes up to 7 or even 8 instead of the usual 6.
Siddhant: So instead of 6C12 we can have 6C13 or 6C14.
Papa: Yes Siddhant. Since their atomic number is 6, these are all Carbon. Yet because of the
variations in atomic mass we can think of these as different avatars of Carbon.
Prerna: ……..and these avatars are called Isotopes.
Siddhant: This means that 6C13 and 6C14 are the two isotopes of Carbon.
Prerna: So Siddhant has the fact entered your head or not?
Siddhant: Why not? I am intelligent enough.
Prerna (mockingly): Is that so?
Siddhant: That is why you were calling me X Siddhant
number is X and my atomic mass number is Y.
Y plus 1,2, 3
. It means you think my atomic
Prerna: And had you entered an atomic reactor instead of an atom, you would have vapourized
and your isotopes...you know...xSiddhant Y plus 1 or plus two would have come out.
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Siddhant: And what would have become of you?
Prerna: I do not have such silly dreams.
Papa: Some isotopes are stable………. means once formed they remain that way.
Prerna: However, some isotopes are unstable.
Siddhant: What do you mean?
Papa: Some isotopes give out radiation and following the emission of radiation these isotopes
transform into a totally different element.
Prerna: This emission is called radioactive radiation.
Papa: ………..and the process is called radioactive decay.
(Dr Prabhat; a radiologist, enters, give appropriate sound effects of footsteps)
Prabhat: Discussion on radiation that too early on a Sunday morning and in the presence of a
radiologist... who dared to do it?
Papa: Hello, Prabhat welcome.
Siddhant: Good morning X-Ray Uncle.
Prerna: Don’t say X Ray Uncle, say Prabhat Uncle. He is a radiologist and radiologists don’t do
just X-rays.
Papa: Don’t fight you two...go and arrange for some tea for your Uncle.
(Scene Change music)
Atom: So here I am yours faithfully…..atom. You have heard all that people talk about me……dry
academic talks...as if they want to inject all the available information into your brains in one go.
So it is my responsibility to give you a break; to present some entertaining and interesting
information, isn’t that so? Well then, while the family drinks tea let us go and meet Professor
Soddy. What did you say, you do not know who Professor Soddy is. He is Frederick Soddy, an
English radiochemist who explained that radioactivity is due to the transmutation of elements.
He also proved the existence of isotopes of certain radioactive elements. Radiochemist……..an
interesting combination...OK let’s go and meet him.
(Scene Change music)
Scene-3
Time: Evening.
Locale: Frederick Soddy’s laboratory.
(Scene Opening music-------------------------------------------------------------------------------------Fades out)
(Frederick Soddy and Margaret Todd are there)
Soddy (Muttering to himself): 8, 9, 10, 11...just 11...but...but they are 40.
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Margaret: 12...13....
Soddy: What are you counting, Margaret?
Margaret: Just counting how many times you have cricked the room, Frederick Soddy,
radiochemist the great. (Laughs)
Soddy: Don’t joke Margaret, I am worried about a problem.
Margaret: worried……….so worried that you forgot I am sitting here for half an hour.
Soddy: I am sorry Margaret. The fact is that I am confused.
Margaret: When are you not confused Frederick. It still amazes me that you did not write down
Carbon instead of signing your name in the marriage register.
Soddy: Margaret please.
Margaret: OK soddy……well let me also know what is your confusion?
Soddy: Margaret you know about Mendeleev and his periodic table, don’t you?
Margaret: Of course, what next?.
Soddy: Well if you look at the heavy elements ...Uranium to Lead. ..there is place for 13
elements.
Margaret: So what is the trouble?
Soddy: Well, when I studied the radioactive decay then I found that there are 40 elements
between Uranium and Lead.
Margaret: 40 elements but only 11 spaces……problem indeed is serious. Soddy why don’t you
put 3 or 4 elements in one space on the periodic table?
Soddy: Do treat this seriously Margaret.
Margaret: ……..I am serious, Frederick.
Soddy: You know that an element can only occupy one unique space on the periodic table, do
you?
Margaret: Yes.
Soddy: ……..then how can you put put 3 or 4 elements in one space on the periodic table?
Margaret: Frederick see, when you have to fit in 40 elements in 11 spaces then it follows that
you will have to fit in more than one element in one given space.
Soddy: OK, but my dear doctor Margaret Todd, elements are arranged in the periodic table in
accordance with their atomicnumber
Margaret: Right
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Soddy- This way these three or four elements which I will put in same space will have the same
atomic number but different atomic mass.
Margaret: what, This is a novel finding.
Soddy: There is no other explanation for my observations. What should I name such an element
Margaret……..these elements that have same atomic number but different atomic masses? I
have problem finding a name for them.
Margaret: Another problem, Frederick...looks like you love being surrounded by problems.
Soddy: Not surrounded by problems, Margaret...I search for solutions. So what should I name
these elements...think Margaret, think. After all you are not just a doctor but are a writer
too...an author.
Margaret: In Greek they have a term called Isotope. It means “in the same place”. Can we use
this term for these troublesome elements of yours?
Soddy (Excited voce): Isotope……..Isotope! Eureka!!! You are a genius Margaret! Dr Margaret
Todd.
(Scene Change music)
Scene-4
Locale- A room inn Siddhant’s home
Time- Morning
(Scene Opening music-------------------------------------------------------------------------------------Fades out)
(Siddhant, Prerna, Papa and Dr. Prabhat have just finished their tea)
Prabhat: Good tea, Prerna.
Siddhnat: XRay Uncle…..sorry I mean Prabhat Uncle... Isotopes are atoms with the same number
of protons , but with different numbers of neutrons .
Prabhat: Yes, you are right. But many isotopes are unstable.
Siddhant: Papa was also telling the same thing.
Prabhat: Do you know how these isotopes stabilize themselves?
Prerna: …….by giving out ionizing radiation.
Siddhant:…….ionizing radiation, What is this?.
Prabhat: Radiation that has enough energy to knock out electrons from atoms, is called ionizing
radiation.
Siddhant: So it creates an ion out of the atom, it hits, right Prabhat Uncle?
Prabhat: Right Siddhant.
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Prerna: Ionizing radiations are of different kinds too, isn’t that so Uncle?
Prbhat: Yes, but the radiation emanating from these isotopes are essentially of three kinds.
Siddhant: What? Are they called Alpha, Beta and Gamma?
Prabhat: Yes. Alpha particles are the commonest.
Prerna: Alpha particles consist of two protons and two neutrons. Just like the nucleus of the
element Helium.
Prapbhat: Yes. So, Prerna tell me what will happen to an element that loses an alpha particle?
Prerna: It will become another element altogether...an element whose atomic mass will be less
than the original element.
Prapbhat: You are right Prerna.
Siddhant: Prabhat Uncle, what happens in Beta type of ionizing radiation?
Prabhat: In beta decay a neutron is transformed into a proton and there is emission of a positron
and neutrino.
Prerna: Or else a proton turns into a neutron and there is emission of an electron, and an
antineutrino.
Prabhat: Correct. But in gamma decay, the entire nucleus enters into a lower energy sate after
emission of gamma radiation. Gamma radiation is most powerful electromagnetic radiation.
Siddhant: Why do you say most powerful Prabhat Uncle? Why are Gamma radiations powerful?
Prabhat: This is because of the energy that these radiations have. Alpha radiation is the least
penetrating. It can be stopped by just a thin sheet of aluminium or even by our skin. Gamma
radiation can easily penetrate a thick sheet of Iron.
Prerna: Those isotopes that give rise to ionizing radiation are called radioactive isotopes, aren’t
they Prabhat uncle?
Prabhat: yes Prerna and these radioactive isotopes are the bread and butter for us, radiologists
(Laughs)
Siddhant: How so, Uncle?
Prabhat: This is because these isotopes are used in the diagnosis of many illnesses and tin the
treatment of diseases like cancer.
Siddhant: Then you must need huge quantities of these isotopes. So do you actually need to
manufacture these isotopes?
Prabhat: Yes indeed. We make these by bombarding selected elements with protons by
reactions in nuclear reactors.
Prerna: Uncle, but these isotopes that you make...are they stable or not?
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Prabhat: You know that after a period which is definite for the given isotope, half of its nuclei
decays to form a different element altogether.
Prerna: Yes. And this period of time is called the half-life of that isotope.
Siddhant: I am confused.
Prabhat: There is no scope for confusion here, it is pretty simple really. Suppose there is a
radioactive isotope called A. It gives out radiation and ultimately transmutes into element B.
Suppose its half life is 2 hours.
Siddhant: Ok So?
Prerna: So, in 2 hours half of the sample will be made up of element A and the other half will be
element B.
Prabhat: In the next 2 hours, that is after 4 hours there will be one fourth of element A left and
three fourths will be element B.
Prerna: All radioisotopes have their own specific half-lives ranging from a few minutes to billions
of years.
Prabhat: Yes...take the isotope of Polonium for example. Its half life is just 3 minutes. Uranium235
has a half-life of 700 million years.
Siddhant: Uncle you have used the word radioactivity many times, what is it?
Prabhat: I did tell you that some unstable isotopes give out energy or radiation and try to
become stable by doing so. This property is called radioactivity.
Prerna: In order to reach stability, these atoms give off the excess energy or mass. These
emissions are called radiation.
(Scene Change music)
Atom- I am an Atom. Look, first it was Papa. Now it is Prabhat Uncle lecturing on dry facts and
talking, talking, talking all the time. Let’s go and meet the real hero of radioactivity Antoine Henri
Becquerel.
One day Henri decided to study phosphorescence: the emission of light of one colour following a
element's exposure to light of another colour.
So, as I was saying, he was carrying out an experiment of exposing a material to sunlight and
then wrapping it in opaque paper and placing it on a photographic film before developing the
film. Then one day...scene begins
Scene-5
Time- Evening of a cloudy day
Locale- Lab of Henri Becquerel
(Scene Opening music-------------------------------------------------------------------------------------Fades out)
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Becquerel (in tired tones): It is a cloudy day today. It is almost evening now and I have been
waiting for strong sunlight all day. I had thought of experimenting with a brand new material
today.
Male voice: So is today’s experiment cancelled, Sir?
Becquerel: Yes, there seems to be no other option. Please place the experimental material and
the photographic plate in the drawer of the table.
Male voice: sure.
(Scene Change music)
Atom: The next day, he repeated his experiment but found that the photographic plates had
been ruined as if exposed to light. He was puzzled about how this had happened. He wondered
how the plates covered by opaque covering had become exposed without being exposed to light.
He realized that this could be because of some property inherent in the novel material he was
working on. Do you know what the material he had been working on was? It was Uranium: the
same element that is considered to be an important radioactive element. Becquerel showed that
some isotopes emit energy or ionizing radiations to become stable.
(Scene Change music)
Scene-6
Place: A room in Siddhant’s home
(Scene Opening music-------------------------------------------------------------------------------------Fades out)
(Siddhant, Prabhat and Prerna are chit-chatting)
Siddhant: So, it was Becquerel who first found out about radioactivity.
Prabhat: Later his work was carried forward by Polish scientist Marie Curie who showed that the
emission that Becquerel had mentioned actually emanated from the atomic structure of the
element Uranium.
Prerna: I do not think that scientists knew about the nucleus in an atom...in those days, the
discovery had not yet been made.
Prabhat: No, but the findings of Marie Curie laid the foundations of such studies. It was Marie
Curie who used the term radioactivity for the first time.
Prerna: She also discovered the radioactive element Radium, didn’t she?
Prabhat: Yes she did. She discovered Radium in an ore named Pitchblende. In her quest she
worked with her French husband, physicist Pierre Curie. They began their work in a tin shed.
Siddhant: Why a tin shed?
Prerna: Because they could not afford a proper research laboratory.
Prabhat: It was in this tin shed that they worked long hours, boiling the ore, refining it...trying to
extract radium...then, one day....
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Siddhant: Then one day...what happened one day?
Prabhat: Then one day they succeeded in extracting a small amount of a radioactive element.
Prerna: They named it Polonium in honour of Marie’s motherland, Poland.
Prabhat: Subsequently Marie Curie and her husband Pierre Curie isolated another radioactive
element from pitchblende.
Prerna: In 1902, this element was named Radium.
Prabhat: Prerna, in 1903, Marie Curie, Pierre Curie and Henri Becquerel received the Nobel Prize
in Physics.
Prerna: Marie Curie thus became the first woman to receive the Nobel Prize.
Siddhant: Didn’t Marie Curie receive two Nobel Prizes, Prabhat uncle?
Prabhat: Yes you are right. In 1911 she also got the Nobel Prize in Chemistry in recognition of her
discovery of the elements Radium and Polonium.
Prerna: This also made her the first scientist to get two Nobel Prizes.
Prabhat: Unfortunately the-then unknown deleterious effects of prolonged exposure to
radiation from radioactive elements damaged her bone marrow.
Prerna: As a result she died of aplastic anemia: a fatal condition of the blood.
Prabhat: A great scientist sacrificed her life for the sake of humanity.
(Sad music)
(Scene Change music)
Atom: So friends I have been with you today, from structure of my nucleus to radioactivity...and
I promise that will be with you in the next episode of this radio serial 100 years of atom....
because I am an atom. So be with me on same day same time
(Scene Change music)
(Signature tune……………………………………………………………………………………………………………Fades out)
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