Basics of nucleus , classification

1. P.RAMYA M sc Mphil.,
DEPARTMENT OF PHYSICS

2. BASICS OF NUCLEAR
PHYSICS

3. INTRODUCTION
 Atomic nucleus was discovered in 1911 by
Rutherford.
 Size of the nucleus is 10-14 meter in diameter.
 All atomic nuclei are made up of elementary
particles called protons and neutrons.
 Proton has positive charge of the same
magnitude as that of on electron.
 Neutron is electrically neutral.

4. • Proton and neutron are the two different charge
states.
• That states are called nucleon.
• Species of nucleus known as nuclide.
• It is represented by ZXA
Z is the atomic number.
A is the mass number.
X is the chemical symbol of species.

5. HOW TO FIND OUT THE
NUMBER OF NEUTRONS
• N= Number of neutrons = A-Z
For example 17cl35has
Z=17 Protons, A= 35 nucleons and
N=35-17= 18 neutrons

6. CLASSIFICATION OF NUCLEI
It can be classified as follows
 Isotopes
 Isobars
 Isotones
 Isomers
 Mirror nuclei
Isotopes
Isotopes are nuclei with the same atomic number Z but different mass number A.
Example 14Si28
14 Si29
Isobars
Isobars are nuclei with the same mass number A but different atomic number Z.
Example 8 O
16
, 7 N
16

7. • ISOTONES
Nuclei with an equal number of neutrons.
For example: 6c14, 7N15, 8o16
• ISOMERS
There are atoms, which have the same Z and same A, but differ from one another in their nuclear
energy states.
• Mirror nuclei
nuclei having the same mass number but with the proton and neutron number interchanged.
For example: 4Be7 (Z=4 and N=3)
3Li7 (Z=3 and N=4)

8. GENERAL PROPERTIES OF NUCLEUS
• Nuclear size
Rutherford work on the scattering of α – particles showed that the means
radius of an atomic nucleus is of the order of 10-14 m to 10-15 m
• Nuclear mass
Assumed Nuclear mass = Zmp + Nmn
real nuclear mass < Zmp + Nmn
Zmp + Nmn – real nuclear mass = Δm

9. • Nuclear density
• The nuclear density ρN can be calculated from =nuclear mass/ nuclear volume
Nuclear charge
The charge of the nucleus is due to the protons contained in it. Each proton
has a positive charge1.6×10-19 C.

10. • Electric power generation (nuclear fission / fusion reactors)
• National Security (nuclear weapons stockpile)
• Medical Diagnosis (PET, MRI) cancer treatment with proton or heavy-ion
beams
• Radioactive dating (geology, archeology)
• Household (smoke detectors, americium-241 α-decay)
APPLICATION