Atomic physics=Lectures from Dr. Parvez Ahmed Asstt. Prof., at INMAS, Rajshahi, Bangladesh.

PERIOD
GROUP
B- decay (1 p is added)
i.e. Neutron Decay &
Alpha Decay
B+ decay (1 p is reduced)
i.e. Proton Decay

BASIC TERMS
1. smallest part of a chemical element that still retains the properties of
the element=atom
2. substance that cannot be broken into subatomic fundamental particles
by chemical processes= Element
3. That electrically neutral substance which is formed when atoms
transfer or share their valence shell electrons with other atoms of same
or different element (to complete their valence shells) =
Molecule/Compound
3 KINDS OF MATTER=Elements, Compounds, Mixtures (A mixture is made
from two or more elements, compounds or both - that are not
chemically combined. Most common matter)
Outermost shells are called Valence shells.

BASIC TERMS
Electron Volt=used to express energy (Non-SI) of ion & subatomic particle-that
have been accelerated in particle accelerator.
One electron volt is equal to the amount of energy gained by an accelerating
electron in vacuum using 1Volt electrical potential difference.
One electron volt is equivalent to 1.60207 × 10-19 J.

BASIC TERMS
When metal atoms combine with each other, the outermost/valence shell electrons lose
contact with their parent atoms & move freely around the whole sample. These
freely moving electrons, called conduction electrons, can carry heat energy and
electric charge easily throughout the metal, making metals good conductors of heat &
electricity.
The remaining positively charged atomic centers form an ordered/crystalline structure.

BASIC TERMS
ATOM
NATURAL
Hydrogen to Uranium
(i.e. E 1-92)
All matters in nature are formed by their
combinations
ARTIFICIAL
Neptunium to
(i.e. E 93-118)

BASIC TERMS
ATOM
May be stable, radioactive or
Chemically reactive
If chemically reactive
Stable molecule
CRB same atoms
Stable compound
CRB different atoms
Free radical
CRB different ions
CRB=chemical reaction
between

BASIC TERMS
ATOM/ELEMENT
LIGHT=3
lithium, beryllium,
and boron
(E 3-5)
MEDIUM=4
carbon, nitrogen,
oxygen, and fluorine
(E 6-9)
HEAVY=111
remainder of the
Elements
(Ne=10 & above)
Light elements i.e. hydrogen, hydrogen’s isotope deuterium and helium are formed shortly
after big bang.
Elements heavier than helium and lighter than iron are formed in nuclear processes in stars, and
Elements heavier than iron are formed in supernova explosions.

SPECTRUM OF EMR (after interacting with matter)
(series of 6 colored component (i.e. visible light or simply, light)+ invisible radiations-
arising from splitting of composite/white light when it is passed through a glass prism;
In 1666, discovered by English Physicists Newton)
Each component has separate range of wavelengths, thereby having separate range of
refractions. E.g. violet light refracts more than red light, so when their mixture is
passed through a glass prism-they show separate range of refractions.
Rainbow is a similar, natural spectrum-produced by meteorological phenomena.
Invisible radiations=during 19th
century & later, radio/TV wave & microwave beyond
infrared; X ray & gamma ray beyond ultraviolet was discovered inside spectrum.
(Absorption & Emission)Spectroscopy=study of spectrum’s wavelengths absorbed or
emitted by the sample being analyzed (originating after EMR-Matter interaction)-by
using devices namely spectroscope (to produce & visually observe spectrum),
spectrograph (to observe & photographically record spectrum) and
spectrophotometer (to measure brightness of each 6 component colored light).
In 1859, prism spectroscope was developed by German Physicists Kirchhoff & Bunsen
for chemical analysis.
Audio spectrum=noise analysis by splitting tones having different pitch.
Mass spectrum=compound/isotope analysis by splitting their atoms having different mass
number. Mass Spectrometer is used for such.
EMR=energy bearing wave that always moves at the constant speed of about 300,000 km/sec
(186,000 mi/sec) in vacuum & each wave inside spectrum of EMR arises from moving charged
particle (i.e. electron, proton) and consists of changing electric & magnetic field.

SPECTRUM
(series of 6 component colored/visible light+invisible radiations-arising from splitting of
composite/white light when it is passed through a glass prism;
In 1666, discovered by English Physicists Newton)
After excitation, outer energy level electron emits visible, infrared, and ultraviolet; inner
energy level electron emits x ray; nuclear energy level proton emits gamma ray.
Quantum/Photon=particle-like, discrete packet of electromagnetic radiation.
It is different from matter that it has no mass & always moves at the constant speed
of about 300,000 km/sec(186,000 mi/sec) in vacuum and consists of changing electric
& magnetic field.

SPECTROSCOPY
(study of colors of light/spectrum;)
Each element (having unique set of energy levels) absorbs/emits set of photons (having
characteristic energies similar to an atom’s unique set of energy levels).

CHEMICAL ELEMENTS IN PERIODIC TABLE
(developed independently by two chemists, in 1869 by the Russian Dmitry Mendeleyev and in 1870
by German Julius Lothar Meyer
physical and chemical properties of the elements tend to recur at regular intervals of 2, 8, 18, and 32)
Chemical element
Metal
(electropositive/reducing
agent/electron donor)
& Form +ion/Cation
Non-metal
(electronegative i.e. gains
electron)
& Form -ion/Anion

(developed independently by two chemists, in 1869 by the Russian Dmitry Mendeleyev
and in 1870 by German Julius Lothar Meyer
physical and chemical properties of the elements tend to recur at regular intervals of 2, 8,
18, and 32)
Alkali metal=6 in number (in column 1, valence +1) & last one is radioactive. They
are soft/malleable & highly reactive (i.e. remain in nature as compounds).
Alkaline earth metal=6 in number (in column 2 , valence +2). They are
semisoft/extrudable & reactive (mostly remain in nature as compounds).
Transition metals/elements=40 in number (from column 3 to 12). They have
incomplete penultimate electron shell, variable valences (+1 to +8), form bright
colored compounds, highly conductive to heat and electricity but less reactive
than previous 2 metal groups. They form both ionic and covalent bonds with
anions They have high melting point & magnetic properties too. They act as
catalyst in biochemical & industrial processes (e.g. plastic, petroleum.)
Rare earth metals/Lanthanide series=14 elements incl. Holmium, Z 57 to 70. They
are found in monazite mineral, separated from mineral by precipitation,
separated from each other by ion-exchange method. They are paramagnetic
(i.e. weakly magnetized), pyrophoric (i.e. ignitable in open air). They form alloy
with other metals. They are trivalent except cerium (4+).
Actinide series=First 4 natural radioactive (Z 89 to 92 incl. Uranium) + next 10
synthetic radioactive Transuranium (Z 89 to 102).

18, and 32)
Halogens=First 4 natural +synthetic & radioactive last 1 in number (in column 17,
valence -1). They are highly reactive & form table salt like molecules with
metal (e.g. sodium) and complex ions with both metal & nonmetals. Astatine
behaves most like a metal & is highly carcinogenic.
Noble gases=6 in number (in column 18) & last one radioactive.. They are
commonly unreactive & all are gaseous at room temperature.

18, and 32)
18 columns/groups/families
7 rows/periods (1
2,2
8,3
8,4
18,5
18,6
32,7
32+)

18, and 32)

(stable nucleus must have a 'magic' number of neutrons or protons=82,114,126,184; Also
2,8,20,28,50)
Heavy transuranium elements are produced in particle accelerators by bombarding
atomic nuclei with charged atomic nuclei or nuclear particles (neutrons,
electrons, protons, and alpha particles) to form a heavier element. These super
heavy elements are radioactive and decay into more stable, lighter elements
rapidly.
It is extremely difficult to manufacture large quantities of the elements heavier than
plutonium. This problem is being overcome by bombarding uranium and
plutonium with very intense streams of neutrons in reactors
Bismuth (Z 83) & onward elements decay radioactively.
Hypothetical isotope of super heavy element 114 containing 184 neutrons may have
a comparatively stable nuclear arrangement.
Another island of stability has been theorized to exist around an isotope of element
126. Producing such heavy nuclei will require accelerating much heavier
ions than have been accelerated to date.

UNSTABLE/RADIOACTIVE ELEMENTS
(Excluding K-40, all isotopes of element 84 i.e. Polonium & onward are Radioisotopes)
ISOTOPE/
NUCLIDE
NATURAL ARTIFICIAL
(Radioactive:>3000)
Stable=280
i.e. it can exist by itself
for a long period of time.
Unstable
/Radioactive=83

UNSTABLE/RADIOACTIVE ELEMENTS
(Excluding K-40, all isotopes of element 84 i.e. Polonium & onward are Radioisotopes)
Unstable nuclei created in the laboratory decay rapidly but natural ones decay more slowly.
Natural ones were formed in the interiors of stars more than 5 billion years ago. They were part of the cloud
of gas and dust & formed our solar system incl. our Earth & other planets.
Decay of natural radioactive elements provides much of the energy that heats Earth’s core.
Common (among 83) natural radioisotopes=potassium-40 (19 column 1), thorium-232
& uranium-238 (actinide series 90 & 92).
To estimate amount of isotope presented when mineral was formed, then measure how much has
decayed. Knowing the rate at which the isotope decays, they can determine how much time has
passed. This process, known as radioactive dating.
Only sodium, beryllium, aluminum, and phosphorus has no natural isotopes;
There remains 280 natural stable isotopes on Earth.

History of Particle physics
• 400 B.C.=Democritus gave idea about atom.
• 1808=John Dalton gave idea about atom as indestructible.
• 1896=H. Becquerel discovered radiation emitting nature (natural radioactivity) of Thorium & Uranium.
• 1897=J.J. Thompson discovered electron.
• 1900=Max Planck showed that energy radiates as discrete/particle form (origin of Quantum theory/mechanics).
• 1911=Ernest Rutherford identified α,β & γ radiation and discovered nucleus.
• 1913=Neils Bohr gave Bhor model of atom.
• 1919=proton was discovered by Ernest Rutherford (with prior idea of Eugen Goldstein in 1885).
• 1926=Wave model of atom was theorized by
Louis Victor de Broglie, Schrödinger, Heisenberg etc.
• 1927=Paul Dirac gave idea about anti-electron (positron) in atom.
• 1932=First discovery of Atom probing accelerator (generator, cyclotron & after WW-ll=synchrotron)
• 1932=positron (anti-particle of electron) & neutron were discovered by Carl D. Anderson (in 1936, he also
discovered Meson, predicted by Hideki in 1935) & Chadwick (with prior idea of Ernest Rutherford about neutron in
1920) respectively.
• 1942=Enrico Fermi led first controlled uranium fission reaction
• 1945-Bombs dropped on Hiroshima and Nagasaki.
• 1956= antineutrino & neutrino (lepton) (with prior idea of W. Pauli about neutrino in 1930) were discovered.
• 1964-1995=Murray Gell-Mann & later Glashow lead to discovery of subsequent 6 quarks, other
leptons & Force carrying particles (Bosons) in proton & neutron (Quark/Standard model
of particle physics).
• 1995-onward=research is going on to find graviton, mass yielding-Higgs boson, dark energy (so that theory of
everything-TOE can be established)
German physicist Arnold Sommerfeld’s pupils are Wolfgang Pauli, and Werner Heisenberg.

STANDARD MODEL OF PARTICLE PHYSICS
The theory where elementary/fundamental particles and their interactions are described.
Limitations-
Does not explain why & how some particles get mass and other particles do not.
Most important and most theoretically supported particle-Higgs boson’s existence would
solve that problem
Because, some physicists believe that Higgs boson carries mass between particles
and its mass is expected to be relatively large compared to that of other elementary
bosons.
When gaining velocity near speed of light (e.g. 2.6x108
m/s), mass of a resting/stationary particle (i.e. resting mass)
becomes double-According to theory of relativity.
In nuclear reactions, such velocity of particle/energy is seen
when mass of particle is converted into energy and vice versa.

STANDARD MODEL OF PARTICLE PHYSICS
Sub Atomic
Particles
Excluding antiparticles
4 Stable
i.e. e-
,electron neutrino, muon neutrino,
& proton
Unstable
Remaining particles.
In 1975, tau lepton by Physicists Martin Perl (USA)
In 1983, W & Z bosons by Physicists Rubbia (Italy) & Meer (Holland)
In 1995, top quark by Physicists in California, USA
Among particles, heaviest particle is top quark=179 GeV/c2
In 1970, in California, USA-
Discovery of 1st
Gen.
Quark, related antiquark
& gluon-using high-powered
e-
beam to proton

MASS & WEIGHT;VELOCITY & ACCELERATION
(System=MKS/SI, CGS,FPS)
Mass=total amount of particle in a system/body. It imparts resistance to motion (of that
mass bearing particle).
Weight=total amount of gravitational force on a given mass. It depends on
distance/range of that given mass from gravitational force carrying object. E.g. in
interstellar space, weight is nearly zero.
Velocity=rate of change of distance/position per unit of time (i.e. magnitude/speed) in
particular direction. E.g. meter per second in particular direction.
Acceleration=rate of change of velocity per unit of time. E.g. meter per second per
second.

SPECIAL RELATIVITY
(In special theory (E=mc2
)-when & how matter behaves as its velocity
approaches the speed of light and vice versa)
There is no ultimate reference space/point/place in the micro- or macro-world, where one
can stand and give the final word on how fast everything is moving in relation to
everything else i.e. all frames of reference are equivalent, and calculations of
velocities made from any frame must also be equivalent.
Equivalence of mass and energy:
Assuming that the speed of light in a vacuum is constant, and that physical laws have the
same mathematical form throughout the universe,
when gaining velocity near speed of light (e.g. 2.6x108
m/s), mass of a resting/stationary
particle (i.e. resting mass) becomes double.

RELATIVITY
(In special theory (E=mc2
)-when & how matter behaves as its velocity
approaches the speed of light and vice versa)
There is no ultimate reference space/point/place in the micro- or macro-world, where one
can stand and give the final word on how fast everything is moving in relation to
everything else i.e. all frames of reference are equivalent, and calculations of
velocities made from any frame must also be equivalent.
Einstein’s Photoelectric effect
Photoelectric effect=low-energy photon strikes an atom & ejects (If the photon is
sufficiently energetic) an inner energy level electron from the atom (proving in 1905
that electromagnetic radiation has particle properties, thus contributed to
development of quantum theory).
Energy of the ejected electron depends on the frequency of striking/incident photon.
Use-in photoelectric cell, where e-
ejected from photocathode & moves to anode, under
the influence of an electric field.

QED
(define interaction between charged particle & EM energy)
QED (quantum electro dynamics) superseded the 1860’s classical wave theory of electromagnetic
radiation-which was proposed by British physicist James Clerk Maxwell in 1860.
In 1860, Maxwell successfully predicted that light is a EM wave.
In 1900, Planck predicted that light radiates as ‘Quantum’ or discrete unit.
In 1905, Einstein proved Planck’s theory by his work on ‘photoelectricity’ and gave E=mc2
(special theory of Relativity) assuming particle-wave dual nature in both matter & energy.
3 Interactions of EM energy with matter:
Photoelectric effect=low-energy photon strikes an atom & ejects (If the photon is
sufficiently energetic) an inner energy level electron from the atom (proving in 1905
that electromagnetic radiation has particle properties, thus contributed to
development of quantum theory).
Compton effect/scattering=medium-energy photon strikes an atom’s electron & then both
particles (i.e. e-
& incident/striking photon) scatter/deflect at an angle to the direction
of the path of striking photon. Incident photon, giving some of its energy to the
electron, emits with a longer wavelength and lower energy (proving in 1922 that
electromagnetic radiation has both wave and particle properties, a central
principle of quantum theory).
Pair production=very high-energy (at least 1.2 Mev) photon strikes element of high atomic
weight & a pair of inner energy level electrons (e-
& e+
) are produced and is ejected (If
the photon is sufficiently energetic) from the atom in opposite/divergent direction
(thus providing an example of conversion of energy into mass).

QED
(define interaction between charged particle & EM energy)
Phases of QED/
Quantum mechanics/
Quantum theory/Wave-particle duality
First/Old phase/element=1900-1922
By Planck, Einstein, Neils Bohr
& Arnold Sommerfeld.
New/Joined QED-Special relativity=
1926-1950, by Dirac, Heisenberg, Pauli
etc etc.
According to wave-particle duality,
both particle & forces’ wave must have momentum, discrete/fixed wavelength/frequency and energy.
Wave-particle duality confirms that wave of a given wavelength correspond to particle of a given momentum.
Planck’s constant is product of wavelength & momentum.

A universal constant of nature/Planck’s constant (h)
[energy of emitted photon E equals frequency of emitted photon f multiplied by h]
In 1916-Robert Millikan (USA) successfully measured its value (6.626 × 10-34
joule-second
in MKS system).
Wave-particle duality confirms that wave of a given wavelength correspond to particle of a
given momentum.
Planck’s constant is product of wavelength & momentum.
Energy of Photon is equal to the frequency of Photon multiplied by Planck’s
constant, i.e. E=f x h.

Electromagnetic spectrum
(made by many waves having)

Intrinsic AM/Spin
(Unit is h/2π, where h is Planck’s constant,
Leptons have spins of +1/2)
Spin is the measurement of rotation of a particle. Rotation is measured in multiples of
the constant number h/2p, where h is a number called Planck’s constant, equal to
6.626 × 10-34
joules-sec.
In 1925, Dutch-born American physicists Goudsmit and Uhlenbeck added 4th
quantum
number (spin of electron) to provide complete explanation of atomic spectra.
Later, this number was extended to all particles, namely proton, neutron, nucleus, anti-
particles.
It is measured as integer or half-integer multiples of unit h/2π,
Fermions (i.e. proton, neutron, electron) have odd half-integer spin (1/2, 3/2,...);
Bosons (i.e. photon, alpha particle, meson) have whole integer spin (0,1,...).
Angular/Rotational Momentum
Product of mass & rotation velocity;
In Atomic/Particle Physics, it is
combined by :
Intrinsic/Spin
i.e. rotation around its axis;
Unit is h/2π
Orbital
results from motion of spinning particle.
or=rotating section of a
chine.
pes of Rotation/Circular
vement/Gyration-
nning & Orbiting.

Atoms are composed of 2 regions:
Nucleus: center of the atom that contains the
mass of the atom
Electron: electronic waves carrying definite
energy create regions of negative electric
charge (called orbital) around positively
charged nucleus. Electrons have no real size
& have zero radius.
24 Fermions (Fundamental):6 quarks+
6 leptons, with their anti-particles (i.e.
electron, proton, neutron etc.)
6 Bosons (Fundamental): force
carrying particles (photon, gluon, W
&Z weak force particles + Higgs
boson, graviton)
6 LEPTONS electronic muonic tauonic
charged electron muon tau
neutral neutrino muon
neutrino
Tau
neutrino
ATOMIC STRUCTURE
(Subatomic particles are classified on mass, spin & electric charge;
Fundamental particles form both matter & energy in Universe)
In1936,Physicistsfinalized
these2types:

neutral electron
neutrino
muon
neutrino
Tau
neutrino
FUNDAMRNTAL LEPTONS
(History Range=In 1897, e-
by J.J. Thompson & In 1995, top quark by Physicists in
California, USA)
1st
Generation/Group Leptons (Found in everyday matter):
e-
=stable fundamental particle having electric charge -1(i.e. 1.602 × 10-19
coulomb ) & mass 511 keV/speed of
light squared (Physicists use this unit because mass of particles is small). They have no detectable shape
or structure. They form layer(s) surrounding positively charged nucleus to make the whole atom electrically
neutral. It can spin clockwise or counterclockwise making it acting as a tiny magnet. It is affected by
electromagnetic force & gravitation, as it has electric charge & mass respectively.
Number of electrons in an uncharged atom must be equal to the number of protons, and the arrangement of
these electrons determines the chemical properties of the atom.
Uses of e-
:
1.Used for electrical devices,
2.(By using e- beam) For producing TV picture & X ray,
3.(By using e- beam) For illuminating study object (e.g. virus) in electron microscope.
4.(By using high-energy e- beam) For revealing elementary particles such as protons, neutrons, and even
quarks.
Fundamental particles, meaning
they cannot be broken down further=
provide basic units of matter and energy
in the universe.

neutral electron
neutrino
muon
neutrino
Tau
neutrino
1ST
GEN. NEUTRINOS
1st
Generation/Group Leptons (Found in
everyday matter):
electron neutrino= stable neutral fundamental
particle having little mass not yet detected. It is
so small that it passes right through most
material including earth. It interacts rarely with
other particles because of their tiny size, neutral
electric charge, and very high speed. It travels in
all medium equally at light’s speed in vacuum.
It comes mainly from Sun (@ 70
billion/cm2
/second on Earth’s surface), from
collisions in the atmosphere, and from beta decay
of radioactive elements on Earth. All neutrinos
have a spin of +1/2.
Second and Third generation Leptons are
unstable- i.e. they exist for only a fraction of a
second before decaying into stable First
generation Leptons.
in the universe.
Leptons have spin of +1/2.

neutral electron
neutrino
muon
neutrino
Tau
neutrino
2ND
& 3RD
GEN. NEUTRINOS
2nd
Generation/Group Leptons (Found during
high-energy collisions between particles seen
in Earth’s atmosphere by cosmic particles, in
Particle Accelerator, in stellar explosion- i.e.
supernova etc):
Muon= has electric charge –1 and mass
106 MeV/c2
, i.e. much heavier than
electron.
Muon neutrino=has no electric charge and
little mass not yet detected (Like other
neutrinos).
3rd
Generation/Group Leptons (Found during
high-energy collisions between particles seen
in Earth’s atmosphere by cosmic particles, in
Particle Accelerator, in stellar explosion- i.e.
supernova etc):
tau= has electric charge–1 and mass 1.77
GeV/c2
, i.e. twice that of neutron-which is
the heaviest particle in an atom
tau neutrino=has no electric charge and
little mass not yet detected (Like other
neutrinos).
Second and Third generation Leptons are
unstable- i.e. they exist for only a fraction of a
second before decaying into stable First
generation Leptons.

neutral electron
neutrino
muon
neutrino
Tau
neutrino
HISTORY OF NEUTRINOS
History of Neutrino:
In 1920=while studying beta decay, neutrino is theorized.
In 1930=W.Pauli suggested existence of neutrino.
In 1940=muon was discovered.
In 1956=American physicists Reines and Cowan discovered electron neutrino with its antiparticle.
In 1962=American physicists Lederman, Schwartz & Steinberger discovered muon neutrino during
pion decay.
In 1970=First detection of solar neutrino by first using solar neutrino detector in south Dakota,USA.
In 1975=American physicist Martin Perl discovered tau.
In 1990=At its end, tau neutrino’s existence was indicated with great precision-it is not directly detected.
In 1998=Japanese physicists neutrinos oscillate/convert into other neutrinos (proving existence of their
mass).
in the universe.

NEUTRINO DETECTOR
Neutrino Detector-filled by Cl/Ga;
Based on its rare interaction with particle
Underground
e.g. on ocean floor, under polar ice to detect
SOLAR electron & muon neutrino.
Within reactor or PA
To detect muon & tau neutrino
By getting their interaction by-product=
Muon & Tau.
PA=Particle Accelerator
RARE INTERACTIONS OF NEUTRINOS:
1. When electron neutrino combines with nucleus’ neutron to produce a proton, electron, and energy
(reverse beta- decay), that atom’s atomic number goes up, changing it into a different element.
2. When muon neutrino interacts with nuclei, the collision produces charged muon.
3. When tau neutrino interacts with nuclei, it produces charged tau.

neutral electron
neutrino
muon
neutrino
Tau
neutrino
CHERENKOV EFFECT/RADIATION
(In 1934, Russian Physicist Pavel Cherenkov discovered this photoluminescence during
his study on γ ray, i.e. Photon-transparent nonconducting liquid interaction)
in the universe.
Neutrino Detector embedded/surrounded by water/ice depends on Cherenkov radiation
which is flash of bluish light created from high-energy charged particles like electron,
muon, tau (which are produced during neutrino-matter interaction) moving through
water/ice (transparent nonconducting liquid ) at a speed greater than speed of light in
water/ice.
i.e. emission of bluish light created from high-energy charged particles moving through
transparent nonconducting liquid (water, ice) or solid (e.g. plastic) material at a speed
greater than speed of light in the same medium.
Actually If a high-energy charged particle enters transparent nonconducting/dielectric/
insulating medium at a speed nearly that of light (c), its (charged particle) speed can then
exceed c in that medium.
Because speed of light (c) in that type of medium is reduced to speed= c/n, where n is the
refractive index of the medium.

USES OF ELECTRON-1ST
GEN. CHARGED LEPTON
1st
Generation/Group Leptons (Found in everyday matter):
e-
:
1. Used for electrical devices,
2. (By using e-
beam) For producing TV picture & X ray,
3. (By using e-
beam) For illuminating study object (e.g. virus) in electron microscope.
4. (By using high-energy e-
beam) For revealing elementary particles such as protons, neutrons, and
even quarks.
Ordinary, visible light can only resolute/create image of those objects which are larger than the
wavelength of the light waves illuminating them.
Wavelength of the visible light is millionth of a meter. So for smaller objects, visible light
scatters/throws randomly off the object and do not reveal its shape.
But Electrons have smaller wavelengths than visible light and thereby reveal smaller objects which are
larger than the wavelength of e-
waves illuminating them.
For producing TV picture= e-
beam is produced in vacuum CRT/Picture tube where
negatively charged metal (i.e. cathode) is heated from which e-
emits & accelerates
toward positively charged metal (i.e. anode)

COSMIC RAY (i.e. Extraterrestrial Particles)
(this name is given by American Physicist Robert A. Millikan, who also determined
value of Planck’s constant ‘h’)
Cosmic Particles
87% Proton 12% Alpha particle Others-
heavy elements etc.
Cosmic ray=
Fast-moving subatomic particles that enter earth's atmosphere from outer space. High-energy
(as a result of their high speed) cosmic particles produce secondary particles (e.g. electron, muon &
gamma ray) by interacting with Earth’s atmospheric atoms.
Source-exact source in outer space is still unknown, but interstellar (e.g. X ray binary star system) or
intergalactic space is believed to be source of high-energy cosmic particles.
In 1912- Austrian-American physicist Victor Franz Hess showed that Earth’s atmospheric ionization
occurs due to cosmic particles. And the intensity of this ionization by electrically charged cosmic
particles depends on latitude implying that those particles are deflected by Earth’s magnetic field.
Detectors are tagged on high-altitude balloon or spacecraft (to get outside the atmosphere) to
detect electric charge, mass, and energy of cosmic particles.

COMIC RAY INTERACTION
Cosmic ray-Earth atm.’s
Atom interaction
(30 pions/60 neutrinos)
25% Neutral Pion
75% Charged Pion
Decays to form-
+ Pion=antimuon (positron &
electron neutrino) &
muon neutrino
- Pion=muon (electron &
electron antineutrino) &
muon antineutrino
Cosmic particles produce secondary particles (e.g. electron, muon & gamma ray)
by interacting with Earth’s atmospheric atoms
Pion is made up of Strange quark,
Hence pion is unstable, i.e. decays.

STELLAR (i.e. involving Star) EVOLUTION

Thermonuclear fusion occurs when intense heat and gravitational force cause hydrogen
atoms together
Nebula=cloud of interstellar gas and dust which, by gravitational force, coalesce to form
protostar.
Protostar=A compact/dense form with rising temperature & pressure at its core.
Star=when rising temperature reaches 10 million degrees C (18 million degrees F),
nuclear fusion (i.e. core’s hydrogen turns into helium) in the core starts, releasing
tremendous energy as light (i.e. EMR) & heat.
Red giant=After exhaustion of core’s hydrogen fuel, hydrogen from pericentric layer takes
part in nuclear fusion-resulting expansion of outer layer (i.e. gas & dust).
Nebula=After exhaustion of pericentric layer’s hydrogen fuel, inward collapse of red
giant by gravitation occurs & ejection of its outer layer (i.e. gas & dust) in space is
seen.
White dwarf=After exhaustion of pericentric layer’s hydrogen fuel, inward collapse of
red giant by gravitation occurs but may glow if remarkable amount of energy is
trapped in its core. It may be of Earth’s size but remains extremely compact.
Black dwarf=After release of all trapped energy, it becomes cold & glowless (i.e. black).
Supergiant=After exhaustion of pericentric layer’s hydrogen fuel, core’s helium takes part
in nuclear fusion to form carbon-resulting massive expansion of outer layer (i.e.
gas & dust).
Gravitational collapse & intense heat causes carbon to convert finally into iron.

Supernova=After exhaustion of all fuel, inward collapse of supergiant by gravitation
occurs & subsequent explosion in outer layer is seen destroying this star totally or
keeping its core intact only.
Neutron star/Pulsar (as it emits pulsating radio waves)=After supernova phenomena,
inside iron core’s atomic electrons & protons merge to form neutron-making the core
extremely dense. (this star is first theorized by American astrophysicist
Chandrasekhar in 1934)
Black hole= After supernova phenomena, spared intact iron core is collapsed by
gravitational pull-resulting a central super dense black object which attracts
everything around it.
Thermonuclear fusion occurs when intense heat and gravitational force cause hydrogen
atoms together
Quasar (quasi-stellar)=extremely remote astronomical compact object with very high energy output.
Galaxy=group/assembly of stars, their planets & nebula-held together by gravitation.
They may be spiral, elliptical or asymmetric.
Strength of gravitational pull depends on mass of atom;
Mass of atom is raised by nuclear fusion, induced by intense heat & pressure.

QUARKS-OTHER FUNDAMENTAL FERMIONS
(Any quark or antiquark can have any color charge i.e. Color charges (having 3 color values & 3
anticolor values), via GLUON- among quarks or antiquarks are constantly changing, thereby holding
the identical quarks or antiquarks together)
6 QUARKS 1st
Gen. 2nd
Gen. 3rd
Gen.
+ ⅔ Up Charm Top
- ⅓ Down Strange Bottom
In 1964, American physicists Murray Gell-Mann and
George Zweig
classified proposed quarks as fermions
Antiquarks are fermions
whose
electric charge and
color charge
are opposite
from
those of quarks.
Color charge
(both color &
anticolor values)
results
Strong force.
HISTORY OF QUARK DISCOVERY
In 1950, Proton has cloudlike shell surrounding dense core-
discovered by using high-powered e- beam to proton.
In 1964, Gell-Mann & Zweig theorized for up & down quark;
Strange quark was discovered.
In 1970, in California, USA-First discovery of 1st Gen. Quark,
related antiquark & gluon-using high-powered e-
beam to proton.
In 1974, Charm quark was discovered in California, USA.
In 1977, Bottom quark was discovered.
In 1995, Top quark was discovered in California, USA.

QUARKS-OTHER FUNDAMENTAL FERMIONS
(Any quark or antiquark can have any color charge i.e. Color charges (having 3 color values & 3
anticolor values), via GLUON- among quarks or antiquarks are constantly changing, thereby holding
the identical quarks or antiquarks together)
Quarks=unlike Leptons, they have fractions of fundamental electric charge. They are
always found in pairs (i.e. in mesons) or triplets (i.e. in baryons). Quarks have ½ spin.
1st
Gen. Quarks (found in ordinary/every day matter; They form proton & neutron-which
make up atoms’ nuclei)=
Up type: has electric charge + ⅔ and mass between 1.5 and 5 MeV/c2
.
Down type: has electric charge - ⅓ and mass between 3 and 9 MeV/c2
.
2nd
& 3rd
Gen. Quarks (found in cosmic particles & produced in laboratory resp.)=
Charm type: has electric charge + ⅔ and mass between 1.1 and 1.4 MeV/c2
.
Strange type: has electric charge - ⅓ and mass between 60 and 70 MeV/c2
.
Top type: has electric charge + ⅔ and mass between 170 GeV/c2
.
Bottom type: has electric charge - ⅓ and mass between 4.1 and 4.4 GeV/c2
.
3rd
Gen. quarks are heaviest quarks.
6 QUARKS 1st
Gen. 2nd
Gen. 3rd
Gen.
+ ⅔ Up Charm Top
- ⅓ Down Strange Bottom
In 1964, American physicists Murray Gell-Mann and
George Zweig
classified proposed quarks as fermions
Antiquarks are fermions
whose
electric charge and
color charge
are opposite
from
those of quarks.
Color charge
(both color &
anticolor values)
results
Strong force.

COMPOSITE FERMION (i.e. BARYON)
(It contains odd number of elementary/fundamental fermions,
e.g. triplet of quarks form proton, neutron)
Proton=
Stable & positively charged (+1) subatomic particle. It, with neutron form nucleus of atom.
Mass of the proton is 938 MeV/c2
to 1 GeV/c2
. Its number in the nucleus determines
type of chemical element. It is made of three quarks (2 up quarks & 1 down quark).
It is affected by all four fundamental forces.
Neutron=
Electrically neutral, subatomic particle that forms, other than proton, part of atomic
nucleus. Mass of the neutron is 940 MeV/c2
. It is slightly magnetic and when isolated
from nuclear matter, it decays into proton, electron along with releasing energy. It is
made of three quarks (2 down quarks & 1 up quark). Certain combinations of
neutrons with protons in atomic nucleus make nucleus stable. E.g. if the nucleus has
too many neutrons—one or more neutrons tend to decay.
It is affected by all four fundamental forces.
Other baryons are lambda & sigma particle which are formed by 2nd
& 3rd
Gen. quarks;
These baryons are not found in atomic nucleus & are Unstable.

HISTORY OF BOSONS
(History Range=In 1920, photon by J.J. Thompson & In 1983, W & Z bosons by
Physicists Rubbia & Meer)
History of Boson:
In 1905=Planck & Einstein suggested existence of photon (confirmed In early 1920-by
experiments)
In 1924=Bose & Einstein set rules that define behavior of bosons
In 1925=Pauli developed exclusion principle,
In 1926=Enrico Fermi set rules that define behavior of fermions
In 1934=Japanese physicist Yukawa Hideki suggested existence of pion/pi-meson (confirmed In
1947-by British physicist Cecil Powell).
In 1964=British physicist Peter Higgs suggested existence of the Higgs boson.
In 1970=Gluon (& 1st
Gen. quarks) was discovered in California, USA.
In 1983=Italian physicist Carlo Rubbia and Dutch physicist Simon Van der Meer discovered W
and Z bosons.
Searches continue for graviton, Higgs boson etc.
laser and superfluidity of helium at low temperatures obey Bose-Einstein statistics

4 FUNDAMENTAL FORCES
(Forces that govern all interactions between particles and energy in the universe)
Electromagnetic force=
It (i.e. photon) arises from electrically charged or magnetic particle. It results repulsion
between same charged particles & attraction between opposite charged particles.
Repulsive force is 100 million times stronger than attractive force in atomic nucleus.
Strong nuclear force=
It (i.e. gluon) binds quarks together in hadrons and binds hadrons to one another by
constantly changing quarks’ color charge, overcoming the electromagnetic repulsive
force.
Gravitational force=
It causes attraction between any mass bearing objects. It is weak when the masses are
small, but can become very strong when the masses are great.
Weak nuclear force=
It (i.e. W & Z bosons) governs how heavier fundamental or composite fermions
decay/break up into other particles.
Fundamental force= that govern the interaction between particles and energy in the universe
Gravitational force is the weakest-on the scale of elementary particles and atoms.

FUNDAMENTAL BOSONS
(In 1924, Indian physicist Satyendra Nath Bose, with Einstein developed Bose-Einstein
statistics that defined properties of Boson particles)
Unlike fermions, two identical bosons can occupy the same space.
Fermions have odd half-integer spin (1/2, 3/2,...);but bosons have whole integer spin
(0,1,...).
4 Elementary/Fundamental bosons (called mediators):
Photon=carry EM force/energy which control interactions between charged particles.
Gluon=carry Strong force which (by creating color charge) holds quarks together
(which form hadrons-i.e. baryons=by triplet of quarks/antiquarks & mesons=by pair of
quark-antiquark).
W+, W-, and Z bosons=carry weak force which controls decay (i.e. way unstable
particles change into stable particles) of unstable particles.
Graviton=carry gravitational force which is the attraction between any mass-bearing
objects.
Fundamental force= that govern the interaction between particles and energy in the universe

FUNDAMENTAL BOSON-PHOTON
(has spin=1, no mass or electric charge but carry very high momentum)
Very high momentum of photon is because of its high speed equal to speed of
light,
So when same charged particles approaches to each other, one particle emits this
photon & other particle absorbs that photon, thereby repelling each other.
I.E. Photon transfers electromagnetic force between particles.
FUNDAMENTAL BOSON-GLUON
(has spin=1, no mass or electric charge but carry color charge)
Color charge has 3 color values (i.e. red, green, blue) & 3 anticolor values (i.e. cyan,
magenta, yellow)
Combination of all three possible color charges creates a particle with no color
charge. Also, combination of a color and its anticolor is colorless.

FUNDAMENTAL BOSON-W+, W- & Z
(has spin=1, no color charge but carry electric charges & masses)
W+ and W- bosons have electric charges +1 & –1 respectively,
But Z boson has no electric charge.
W+ and W- bosons have masses 80 GeV/c2
,
And Z boson has mass 91 GeV/c2
.
How W+,W- & Z Boson work:
A decaying particle changes form and emits one of the W+,W- & Z bosons. The emitted
weak boson then decays into other particles.
E.G. In positron decay, a quark (in proton) emits W+ boson & converts to other
quark. Thus that proton converts into neutron. And the emitted W+ boson
immediately decays into a positron & electron neutrino.

FUNDAMENTAL BOSON-GRAVITON (but not yet detected)
(If it exists, will have spin=2 & no mass or electric charge)
W+ and W- bosons have electric charges +1 & –1 respectively,
But Z boson has no electric charge.
W+ and W- bosons have masses 80 GeV/c2
,
And Z boson has mass 91 GeV/c2
.
How W+,W- & Z Boson work:
A decaying particle changes form and emits one of the W+,W- & Z bosons. The emitted
weak boson then decays into other particles.
E.G. In positron decay, a quark (in proton) emits W+ boson & converts to other
quark. Thus that proton converts into neutron. And the emitted W+ boson
immediately decays into a positron & electron neutrino.

COMPOSITE BOSON (i.e. MESON)
(It contains even number of elementary/fundamental fermions,
i.e. a pair of quark-antiquark)
There are six quarks and six antiquarks, so 36 possible mesons may exist.
Important mesons are pion, kaon, B, D, F particle.
They are formed by 2nd & 3rd Gen. quarks; They are not found in atomic nucleus
(rather found during cosmic particle-Earth’s atmospheric atoms interaction) & are Unstable.

Glow/Luminescence (emission of low-energy light)
Vs Incandescence (emission of light by heated materials)
Glow
(i.e. low-energy light emission
at lower temperature than is
needed for combustion )
Fluorescence
(e.g. Interior of fluorescent lamp,
TV screen coated with Phosphor material)
Interval between absorption & emission of light
Is short (<10-5
second)
Phosphorescence
Interval between absorption & emission of light
Is long (many hours)

Glow/Luminescence (emission of low-energy light)
Vs Incandescence (emission of light by heated materials)
Various types of Glow=
1. Chemiluminescence-Oxidization of yellow phosphorus in Air, giving green glow.
2. Bioluminescence-Oxidization of yellow phosphorus in Living organism (e.g. firefly),
giving green glow.
3. Triboluminescence-During breaking, pulling, or scratching certain materials.
4. Electroluminescence-By using Gas in the path of electric discharge, e.g. lightning,
light of fluorescent lamp
5. Photoluminescence-By using visible or ultraviolet light on certain materials, e.g.
phosphorescence of paints
6. Sonoluminescence-By throwing ultrasound in some organic liquids.
7. Roentgenoluminescence-By using X ray on certain materials, e.g. using X ray on
fluoroscope screen

ATOMIC STRUCTURE
(proton’s mass is about 1,840 times the mass of an electron,
Neutrons are about the same size as protons but their mass is slightly greater.)

SUBATOMIC STRUCTURE
HADRON-composite particle
(made by various quarks combination
with gluon)
BARYON/COMPOSITE FERMIONS
-has odd number of quarks
(=proton, neutron)
MESON/BOSONIC COMPOSITES
-has even number of quarks
i.e:1 quark-1 antiquark pair
(=pion, kaon, B, D, F particle)

NUCLEAR STRUCTURE
The story began about 20 years ago, when Maria Goeppert Mayer at the University of Chicago and O. P. L. Haxel, J.
Hans D. Jensen and Hans E. Suess of the University of Heidelberg began to develop a 'shell' model of the
nucleus that consisted of particles moving in a field of nuclear force. The collection of particles (neutrons and
protons) was shown to be particularly stable when the nucleus contained a 'magic' number of neutrons or protons.
The stable structure could be regarded as shells, or spherical orbits, whose capacity for nuclear particles is filled;
it is analogous to the filled electron shells of the noble gases. Magic numbers of neutrons (N) or protons (Z) are
generally recognized as being 2, 8, 20, 28, 50 and 82 in the elements below uranium in the periodic table. The
magic number N = 126 is also significant in this region, as can be seen in the special stability of lead 208
(20882Pb, or Z = 82 and N = 126), which has a doubly magic nucleus. The shell theory has evolved through
many stages, to the point where the potential of single nucleons (protons or neutrons) in a deformed
(nonspherical) nuclear field can be calculated by using 'Nilsson orbitals,' a method developed by the Swedish
physicist Sven Gösta Nilsson.
charged liquid-drop model of the nucleus first put forward by Niels Bohr and John A. Wheeler.
This model assumes for a stable nucleus a spherical, or liquid-drop, form brought about by a
balance between the inwardly directed force of surface tension and the outwardly directed force
of repulsion among the positively charged protons. The model has been developed further to help
in predicting the stability of heavy nuclei with respect to spontaneous fission and other modes of
decay.
extension of the liquid-drop model formulated by W. D. Myers and W. J. Swiatecki of the Lawrence
Radiation Laboratory the potential energy of the nucleus is a function of neutron number, atomic
number and nuclear shape. The nuclei of most isotopes, including those of the lanthanide and
actinide elements, have somewhat deformed shapes, for example ellipsoids, but the nuclei of
isotopes whose shells are filled or nearly filled are spherical. In the absence of filled shells all
superheavy elements would decay instantaneously by spontaneous fission to isotopes with
medium atomic numbers located near the middle of the periodic table.

MAJOR ATOMIC MODELS
• Dalton model=in 1803, depicted atom as tiny, indestructible particle with no internal
structure.
• Thomson model= in 1898, discovered electron & described that electrons are embedded in
positively charged sphere.
• Rutherford Model=in 1909, showed most of an atom’s mass is concentrated in centrally &
positively charged nucleus.
• Bohr model=in 1913, proposed that electrons having definite energies, move in various,
circular orbits around nucleus & an atom emits electromagnetic radiation only when an
electron in the atom jumps from one quantum level to another.
• Wave model=from1926 to present time, stated that electrons move around nucleus as
definite quantized waves or energy levels. Existing region(s) of space in each energy level is
also quantized accordingly .
radius(n) = n2
a0
a0 = Bohr radius = 0.529 Å

CRITICISM OF MODELS
Indivisible Electron Nucleus Orbit Electron
Cloud
Greek √
Dalton √
Thomson √ Had no
idea
Rutherford √ √ Had no
idea
Bohr √ √ √
Wave/Vibra
tion (i.e. regular
repetitions)
√ √ √

4 Quantum numbers for Fermions-e-
/p+
/n
(to define each fermion’s energy in orbitals)
Principal (n) QN=specific energy level,
Secondary/Angular (l) QN=number of orbital,
Third/Magnetic (m) QN=number of direction of orbital
Fourth/Spin (i.e. intrinsic angular momentum) QN (ms)=number
of direction of rotation
Pauli exclusion principle=2 identical fermions (not
bosons) cannot occupy same quantum
state/orbital.
(i.e. describe arrangement & behavior of
fermions in orbitals)
[fermions have spin of odd half integers e.g. ½,3/2,
5/2 etc and bosons have spin of whole integers
e.g. 0,1,2 etc.]
ORBITAL=pattern of rotation around nucleus by
specific amount of energy-bearing rotating
electron.
In 1927, Paul Dirac theorized that e-
has spin & antiparticle
In 1925, Pauli developed exclusion principle,
In 1926, Enrico Fermi set rules that define behavior of fermions
In late 1926, e-
is regarded as fermion

/p+
/n
(to define each fermion’s energy in orbitals)
Fourth/Spin QN (ms)=number of direction of rotation
no two electrons in an atom can have
identical sets of quantum numbers=
Exclusion principle of Austrian-Swiss
Physicist W. Pauli.

/p+
/n
(to define each fermion’s energy in energy levels & orbitals)
Fourth/Spin QN (ms)=number of direction of rotation
Arrangement of electrons in an atom depends on:
1. Quantization of electron energy, which limits the regions of space that electrons can occupy
2. Pauli exclusion principle (i.e. identical fermions cannot occupy same quantum state/orbital)
n=1,2,3 etc l=0 to n-1
(1n=l=0=s,
2n=l=0&1=s&p,
3n=l=0,1&2=s,p&d,
4n=l=0,1,2&3=s,p,d&f orbital)
m=2l+1
(l=0=s=1,
l=1=p=3,
l=2=d=5,
l=3=f=7)
2n2
(thus 2,8, 18,
32 in n=1,2,3,4
respectively)
2(2l+1) (thus
1n=l=0=s=2,
2n=l=0&1=s&p=2&6
3n=l=0,1&2=s,p&d=2,6&10
4n=l=0,1,2&3=s,p,d&f=2,6,10&14
)
Max. no. of electrons
Color charge enables two up or down quarks
in protons and neutrons to be different from
each other, thereby exclusion principle is not
violated by the Quark fermions.

ATOMIC ENERGY LEVELS
ELECTRON ENERGY LEVEL=
• Every element has definite energy levels
i.e. definite energy transitions i.e. definite
frequencies and wavelengths of light
which can be emitted the element (solid,
liquid or gas) is given enough energy via
heating or electric current. They give rise
to definite emission (continuous or line)
spectrum. By seeing line spectrum, an
element can be identified definitely.
• Energy levels referred to the
orbitals/regions of space in atoms where
electrons with same energies may present
with 90% chance.
• The level closest to nucleus, has
electrons with lowest energy & the level
farthest from nucleus, has electrons with
highest energy.
• In a stable atom, electrons firstly fill the
lowest energy levels and consistent with
the pauli exclusion principle, the aufbau
principle, and hund's rule.
• Photon is emitted when electrons move
from high energy level to low energy level.
And the energy of photon will be equal to
difference between these levels

GROUND/STABLE STATE of atoms= Complete & orderly filling up of innermost energy
levels, closest to nucleus by electrons indicate this state.
Atom’s energy is minimum at this state.
EXCITED STATE of atoms= Very transient (10-13
,10-14
… SECOND) presence of electrons
in outer energy level in excited atoms indicate this state.
When atoms are excited by heat, electricity, light or some other form of radiation,
atoms’ electrons instantly absorb energy & jump from inner to outer energy level for
transient period and then emit equal amount of absorbed energy (as photon/tiny flash of
light energy) to fall back to inner, vacant energy level.
Each excited elements’ atom’ electronic structure thus shows a distinct set of
emitted energies (i.e. colors of light)-studied by spectroscopy.
3.METASTABLE STATE/ISOMERIC STATE= RELATIVELY LONG-LIVED (second,
minute or even year; 10-12
SECOND or more.) EXISTENCE OF EXCITED STATE
ELECTRONS OR NUCLEONS IN LOWER ENERGY LEVEL.
SPONTANEOUS ENERGY EMISSION IS OCCURRED DURING THE
CONVERSION OF EXCITED STATE TO METASTABLE STATE & THEN TO
GROUND OR LOWER ENERGY STATE ELECTRONS OR NUCLEONS.

EXCITED STATE
METASTABLE STATE
GROUND STATE
APPLICATIONOFENERGY
(FORIT’SINDUCED
ABSORPTIONINTO
ELECTRONSOR
NUCLEONS)
SPONTANEOUS EMISSION OF ENERGY
STIMULATED EMISSION OF RADIATION

EXCITATION & IONIZATION OF ATOM
1. EXCITATION=PROCESS OF RAISING LOWER ENERGY LEVEL
ORBITAL ELECTRONS OR NUCLEONS TO UNOCCUPIED HIGH
ENERGY LEVEL SHELLS OR ORBITS.
2. IONIZATION= PROCESS OF CREATING CHARGED ATOM.
HERE ELECTRON IS REMOVED FROM A ATOM. THUS AN ION PAIR IS
PRODUCED.
HOW THEY CAN BE PRODUCED= BY
1. CHARGED PARTICLE-MATTER INTERACTION
2. Heat
3. Electricity
4. Light
Atoms are made excited by heat, electricity, light or other form of radiation.

RADIATION
Radiation=Emitted energy from unstable atom, which is particulate or
wave in nature.
Ionizing radiation=High energy radiation, which is capable of removing

ACTIVITY & RADIOACTIVITY OF A RADIOACTIVE SAMPLE
Activity=number of nuclei decaying per second.
Measured in becquerels (Bq) in S.I unit or curie (Ci) conventional unit.
(1 Ci=3.7 x 1010
Bq)
Radioactivity=spontaneous disintegration or decaying of radionuclide with
emission of radiation.
Radioactive transformation (or, decay) =various spontaneous ways through which
unstable nuclide loses its energy.

NUCLIDE
NUCLIDE=atomic nucleus which is characterized by
its nucleon numbers & energy content.
Varieties- (An element’s identity is determined its proton
number)
Isotopes-nuclides of a same element having same proton
number (Z) but different neutron numbers (N)
[hence different mass numbers (A)].
EXAMPLE=C-14(unstable), C-12 (stable);
Isobars-nuclides of different elements having same mass number (A)
but different proton (Z) & neutron (N) numbers.
EXAMPLE=38Sr-90 (unstable)- 39Y-90 (unstable)-40Zr-90 (stable)
Isotones-nuclides of different elements having same neutron
number (N) but different mass (Z) & proton
numbers (A).
Isomers-excited or metastable state of nuclides (i.e. unstable
or radionuclides) of a same element.
A transition from one isomer to another is
accompanied by emission or absorption of a gamma
ray, or the process of internal conversion
NUCLIDE
NATURAL
280 (stable)+
83 (unstable)
ARTIFICIAL
>3000

CHART OF NUCLIDES
Stable Nuclides

NUCLIDE STABILITY & RADIOACTIVE/DECAY
SERIES/SCHEME/CHAIN
From viewpoint of forces-
Balance between two forces make nuclide stable
• Strong (nuclear) force- hold nucleons together.
• Electromagnetic force-hold protons together.
From viewpoint of neutron (N) & proton (Z) number-
• N=Z, for lighter nuclide (A<50).
• N>Z, for heavier nuclide (A>100).
Radioactive/Decay series=when a radionuclide decay into stable nuclide via other radionuclides.
example- 99
Mo-99m
Tc-99
Tc-99
Ru (stable)

FORCES/WAVES/ENERGYS/INTERACTIONS
(They define everything’s nature & interaction among everything;
These waves are massless & travel at the speed of light;
Fundamental particle Bosons create these 4 forces.)
This attractive force acts
between every mass-carrying
Objects.
Quantum/Discrete packet of EM energy is called photon
This nuclear force binds
protons & neutrons in
atom’s nucleus.
It acts on every electric
charge(+/-)-carrying
Objects.
Quantum/Discrete packet of GRV energy is called graviton
Quantum/Discrete packet of STR energy is called gluon
Quantum/Discrete packet of WK energy is called W,Z

RADIOACTIVE DECAY
(mediated by weak force/interaction which is carried by W & Z bosons)
Beta decay (Isobaric transition)-Here nucleons are into opposite particles. Energy =
few KeV to 10 MeV. 2 types (Beta particles include high energy electron & positron
ejected from radionuclide.)
1.Electron emission/Beta minus/Negatron (in radionuclides having excess
neutrons)=Here proton, electron (e-
) & anti-electron neutrino are released from a
neutron. Example:90
Sr38=e-
+90
Y39=e-
+90
Zr40 (stable), 99
Mo42 =e-
+99m
Tc43=e-
+99
Ru44 (stable)
2.Positron emission/Beta plus (in low atomic weight radionuclides having excess
protons)=Here neutron, positron (e+
) & electron neutrino are released from a
proton. Then positron annihilates with orbital electron & produce high energy (25 Mev)
gamma radiation. Example:18
F9=e+
+18
O8
3.Electron capture (EC) (in higher atomic weight radionuclides having excess
protons)=Here neutron & neutrino are released from a proton when it absorbs inner
orbital electron. Here simultaneous emission of characteristic x-ray or Auger electron
occurs. Example:125
I53=125m
Te52(metastable state)
“Alpha or beta emission usually leaves the nucleus with excess energy,
which it unloads by emitting a gamma-ray photon.”

RADIOACTIVE DECAY
(mediated by weak force/interaction which is carried by W & Z bosons)
Alpha decay [in radionuclide of very heavy element having excess neutrons like radium
(Ra), thorium (Th), uranium (U)-Here Alpha particle is ejected from]=Here low speed,
heavy Alpha particle having 2 protons & 2 neutrons is released. It
is identical to helium nucleus and has 2 positive charge. Energy = 3 to 7 MeV.
Example:226
Ra88=α2+
+222
Rn86gas (stable)
Gamma decay [in radionuclide of very heavy element having excess neutrons like
radium (Ra), thorium (Th), uranium (U)-Here Alpha particle is ejected from]=Here low
speed, heavy Alpha particle having 2 protons & 2 neutrons
is released. It is identical to helium nucleus and has 2 positive charge. Energy = 3 to 7
MeV. Example:226
Ra88=alpfa2+
+222
Rn86gas (stable)
Internal conversion (IC) decay (emission of characteristic x-ray or Auger electron in
radionuclide of same element )=Here inner orbital electron is emitted by the kinetic
energy which comes from nuclear transition from high energy level to lower energy
level. Here simultaneous emission of characteristic x-ray or Auger electron occurs. But
no gamma ray emission is seen. Example:125m
Te52=125
Te52(stable)

ACCELERATORS
(in 1932=cockcroft,walton,van de graaf for generator & lawrence,livingston for cyclotron & mcmillan
for synchroton)
Energize/accelerate voltage of beams of electrons, protons, deuterons, heavier ions, and X rays
to probe atom
High energy type used in research on elementary particles & low energy type used is
applications inside industries and laboratories
“Alpha or beta emission usually leaves the nucleus with excess energy,
which it unloads by emitting a gamma-ray photon.”

IONIZATION ENERGY & NUCLEAR
BINDING ENERGY
1. IONIZATION ENERGY/ORBITAL ELECTRON BINDING ENERGY= ENERGY
REQUIRED TO REMOVE AN ELECTRON FROM AN ATOM. IT IS MEASURED IN
ELECTRON VOLT (eV), THIS ENERGY IS INVERSELY PROPORTIONAL TO
ATOMIC SIZE.
2. NUCLEAR BINDING ENERGY= ENERGY REQUIRED TO DISASSEMBLE A
NUCLEAS INTO FREE PROTONS AND NEUTRONS. IT IS MEASURED IN MEGA
ELECTRON VOLT (MeV). THIS ENERGY IS EXPRESSED BY THE FORMULA-
E (NUCLEAR BINDING ENERGY) =m( NUCLEAR MASS) x c (LIGHT VELOCITY)2
**MASS DEFICIT/DEFECT/DEFICIENCY= MASS OF AN ATOM OR NUCLEUS IS
LESS THAN THE SUM OF MASSES OF ITS INDIVIDUAL CONSTITUENTS. IT IS
CONVERTED INTO BINDING ENERGY ACCORDING TO EINSTEIN’S THEORY. IT
IS MEASURED IN ENERGY UNIT.

PHOTO-ELECTRIC EFFECT
In 1905, Einstein showed that electrons
are ejected upon hitting of metals by
lihgt.

ATOMIC EMISSIONS
1. CHARACTERISTIC X RAY= IT IS AN ELECTROMAGNETIC RADIATION
OF ABOUT 100 eV OR MORE ENERGY.
IT IS PRODUCED DURING OUTER ORBITAL ELECTRON TRANSIT
INTO INNER VACANT ORBIT.
2. AUGER ELECTRON= IT IS AN EMITTED ELECTRON WHICH IS
EMITTED FROM THE OUTER ORBITAL AS A RESULT OF ENERGY
WHICH IS PRODUCED DURING OUTER ORBITAL ELECTRON
TRANSIT TO INNER VACANT ORBITAL.
**IN AUGER EFFECT, TWO ELECTRONS ARE REMOVED FROM THE
ATOM (DOUBLY CHARGED ATOM).
**USUALLY ELEMENTS WITH LOW ATOMIC NUMBER (Z<24) EMIT
AUGER ELECTRON & ELEMENTS WITH HIGH ATOMIC NUMBER (Z>45)
EMIT X RAY.

ATOMIC EMISSIONS
1. PAULI’S EXCLUSION PRINCIPLE= TWO ORBITAL ELECTRONS,
BEING ON A SAME ORBIT OR SUBSHELL MUST SHOW OPPOSITE
SPIN.
2. HUND’S RULE (OF MULTIPLICITY)= IN CASE OF ORBITS OR
SUBSHELLS HAVING SAME ENERGY LEVEL, ELECTRONS OCCUPY
THOSE ORBITS OR SUBSHELLS SINGLY AND SHOW THE SAME
SPIN.
3. AUFBAU BUILDING UP PRINCIPLE= LOW ENERGY LEVEL ORBITS OR
SUBSHELLS ARE FILLED UP FIRST BY ORBITAL ELECTRONS THAN
THE HIGH ENERGY LEVEL ORBITS OR SUBSHELLS.

ATOMIC EMISSIONS
AUFBAU PRINCIPLE

Atomic physics=Lectures from Dr. Parvez Ahmed Asstt. Prof., at INMAS, Rajshahi, Bangladesh.

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