This document discusses the history and concepts of nuclear chemistry. It begins by explaining that nuclear chemistry is the study of how the structure of the atomic nucleus influences the physical and chemical properties of elements, as well as the energy released by nuclear reactions. It then provides background on key discoveries in nuclear chemistry including Henri Becquerel's discovery of radioactivity in uranium in 1896 and Marie and Pierre Curie's isolation of polonium and radium from uranium ore between 1898-1902. The document also summarizes the concept of parity and its conservation in nuclear reactions, noting that parity conservation applies to strong interactions but not weak interactions, as evidenced by experiments on beta decay in the 1950s.

1. NUCLEAR
CHEMISTRY
•Introduction
•Parity and its conservation

2. •Nuclear chemistry is the study of the physical and chemical properties of
elements which are influenced by changes in the structure of the atomic nucleus.
It also deals with the energy released from nuclear reactions and its uses.
• It is also termed as radiochemistry which includes the study of the formation
of the elements in the universe, the design of radioactive drugs for diagnostic
medicine and many other applications.
•The nucleus of an atom contains protons (+1charge) and neutrons (no
charge).
•The strong nuclear force is the strongest force known Protons and neutrons
are very close together.
• They exchange a teeny bit of mass back and forth. When disrupted, the
mass is converted to energy according to E=mc2 The mass is tiny. The energy
is immense.
•The three most common forms of radioactive decay are alpha(α), beta(β)
and gamma(γ)
2
INTRODUCTION

3. 3

4. HISTORY NUCLEAR CHEMISTRY
After Wilhelm Röntgen discovered X-rays in 1882, many scientists began to work on ionizing
radiation. One of these was Henri Becquerel, who investigated the relationship
between phosphorescence and the blackening of photographic plates. When Becquerel
(working in France) discovered that, with no external source of energy, the uranium
generated rays which could blacken (or fog) the photographic plate, radioactivity was
discovered. Marie Skłodowska-Curie (working in Paris) and her husband Pierre
Curie isolated two new radioactive elements from uranium ore. They
used radiometric methods to identify which stream the radioactivity was in after each
chemical separation; they separated the uranium ore into each of the different chemical
elements that were known at the time, and measured the radioactivity of each fraction. They
then attempted to separate these radioactive fractions further, to isolate a smaller fraction
with a higher specific activity (radioactivity divided by mass). In this way, they
isolated polonium and radium. It was noticed in about 1901 that high doses of radiation could
cause an injury in humans. Henri Becquerel had carried a sample of radium in his pocket
and as a result he suffered a highly localized dose which resulted in a radiation
burn. This injury resulted in the biological properties of radiation being investigated,
which in time resulted in the development of medical treatment.
4

5. Parity and its conservation
5
• Parity – Equality or Balanced
• Nuclear property connected with Symmetry properties of wave
function is parity.

6. PARITY
AND
ITS
CONSERVATION
6
CONSERVATION OF PARITY
•Conservation of parity means
the products of parities of
reactants must equal the product
of parities of the resultant.
•That two mirror images of each
other such as left spinning and
right spinning particles should act
as the same.
•The idea dose not apply to
subatomic particle interactions
that are weak.
Even Parity P=+1.
Odd Parity P=-1.
•Use of concept of parity in Nuclear
Reaction and Nuclear Decay Process
because the parity of an isolated
system like its total energy
momentum ,angular momentum
and Statistics a law of conservation
is also valid.
•Expected parity is found to be
conserved In all strong interaction
involving the Emission of Photons
and Nucleons.
• Weak interaction involving
electrons Neutrinos and where there
is evidence of breakdown of parity
conservation.

7. 7
• Lee and Yang who first observed paradoxical result in reaction
involving Ʈ and mesons.
• To verify this β decay of 60Co in strong Magnetic field at low
temperature of 0.1k.
• The betas were emitted isotropic ally clearly showing an absence of
symmetry and hence non conservation of parity.

8. 8

9. THANK YOU
PARITY
AND
ITS
CONSERVATION
A. Mohammed Ashik Babu
II M.Sc Chemistry B Section
21PCHB016
9