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Modern
Physics
Introduction
To examine the fundamental nuclear
model
To examine nuclear classification
To examine nuclear fission and fusion
Detection Devices
Geiger counter
Scintillation counter
Cloud chamber
Bubble chamber
Superheated liquid
Fundamental Particles
Democritus introduced the word
which in English translates as atom
Elementary Particles

The name given to protons, neutrons and
electrons
Today we use the term "fundamental"
for the six types of quarks and the six
leptons
Classification of Matter
Hadrons: Particles made of quarks. Protons,
Neutrons and their Anti-particles
Leptons: Are NOT made of sub particles.
Electrons are examples of Leptons
Hadrons are further broken into Baryons and
Mesons. ( both break down into Quarks)
Hadrons
Hadrons break down into two
groups
 Baryons are made of 3 Quarks
 Mesons made up of 2 quarks and
anti-quarks
***(must add up to an integer not a
fraction)
Leptons
Leptons
are fundamental particles that
have no strong interactions
Lepton is Greek for "light particle”
electron there are heavier leptons, of which
the first to be found was the muon
The TAU is 12th (quarks + leptons)
fundamental building blocks of all matter.
Quarks
Quarks are fundamental matter
particles that are constituents of
neutrons and protons and other
hadrons
Proton -- composed of two Quarks
up quarks and a down quark
Sample Problem
A Baryon may have a charge of
-1/3e
 0e
 +2/3e
 +4/3e

Correct answer is 0e (all types of matter
must have an integer charge)
Scale of nature
Particles are
classified by
size and charge
Forces give all
matter their
characteristics
and properties
Neutrinos (type of
Lepton)
These particles
are so small that
they pass right
through the
Earth with
interacting with a
single atom!!!
Four fundamental
interactions
Force : the effect
on particle due to
another particle
Interaction: the
forces and decays
which affect a given
particle
Strong Force
Quarks and Gluons have a type of
charge that is NOT electromagnetic
The “color” charged particles are very
powerful (STRONG)
Quarks are glued together with
GLUONS (Nuclear Energy)
Weak Force
The stable matter of the universe is
made up of the two least massive
quarks: UP and Down and the least
massive Lepton, the electron ( A
Hydrogen Atom)
When a quark or lepton changes type
(muons changing to an electron) is
called a “flavor” weak interaction
The components of the nucleus are
called nucleons.
The two principle nucleons are the
proton with a charge of +1e and
the neutron which is uncharged.
All atomic nuclei (nuclides) and their
X
components may be represented
by the symbol below.
A
Z
A
Z
X
X is the name of
the particle
A is the mass #
Z is the atomic #
Chemistry
Symbols
Isotopes
Nuclei that have the same atomic number,
but different mass numbers.
Hydrogen
Deuterium
Tritium
Nuclear Reaction
Represented by a balanced nuclear
equation
15
7
N  H  C  He
1
1
12
6
4
2
Nuclear Fission &
Fusion
Fission is the chain reaction splitting of
an atom
Fusion is the joining of light nuclei to
form a heavier more stable nuclei
Reference Chart : Standard Model
Reference Chart
Reference Chart
Equations
Ephoton = hf = hc/wavelength
Ephoton = Ei – Ef
E
= mc2
All equations calculate the amount of
energy in units of eV or J. The
conversion is based on the energy of a
single electron or mass
Sample Problem
Calculate the energy of the photon that
is emitted when a hydrogen atom
changes from energy level n=3 to 2
Ephoton = Ei – Ef
= (-3.40 eV) – (-1.51 eV)
= - 1.89 eV
Sample Problem
What is the Radiant energy of a beam
of light whose frequency is 5.0 x 1014
Hz
Ephoton = hf = hc/wavelength
= 6.6 x 10-34 J*s (5.0 x 1014 Hz)
= 33 x 10 -20 J
Summary
Atomic Particles are composed of subnuclear particles
The nucleus is a conglomeration of
Quarks which manifest as Protons and
neutrons
Each elementary particle has a
corresponding anti-particle
The fundamental source of energy is
the conversion of mass into energy