Radioactivity Basics covered in a very precise way.pdf

It entials everhtything related to radioactivity in a precise manner

1. Radioactivity

2. WHAT IS RADIOACTIVITY?
 RADIUS (Ray); ACTIVUS (Activity)
 Radioactivity is the process by which a
 nucleus of an
unstable
 atom loses energy by emitting ionizing
radiation
The instability in the atom is the result of an unstable
nucleus trying to become more stable
Nuclear instability is related to whether the neutron
to proton ratio is too high or too low

3. Stability of Nuclei
1.Larger nuclei are less stable – all
nuclei that contain more than 83
protons are radioactive
2.The ratio of neutrons to protons also
determines if an element is
radioactive
•Nuclei with too many or too few
neutrons compared to protons are
usually unstable, and thus,
radioactive

4. WHAT IS Radioactive Substance?
A material that spontaneously emits this kind of radiation which
includes the emission of alpha particles,
 beta particles, gamma
rays
 and conversion electrons 

5. Why are elements radioactive?
Unstable nucleus:
•Has excess energy
•Wants to go to
“ground state”
•Becomes stable by
emitting ionizing
radiation

6. All the elements heavier than Bismuth (At # 83) are radioactive

7. Some Key Definitions Before moving on
•Z = The Atomic Number. It’s the Number of Protons in the
nucleus of an Atom.
•Nucleus: It’s where the Protons and Neutrons are located in an
Atom.
•Protons: Positively Charged Particles in the Nucleus of the atom.
Mass = (approx.) 1 AMU
•Neutrons: Neutrally charged particles in the nucleus of an atom
Mass = (approx.) 1 AMU
•Mass Number of an atom: Number of Protons + Number of
Neutrons in the nucleus of an atom.

8. Alpha Particles (2n, 2p)
Beta Particles (e- or +)
Photons (hv)
(x or gamma rays)
Paper Concrete
Radiation Types

9. Kinds of Radioactivity
The three main decays are Alpha, Beta & Gamma

10. Nuclear Decay
Neutron decays into a proton
& an electron is given off
2 protons & 2 neutrons
Only Energy is release

11. Occurs when the nucleus is too large
An alpha particle is emitted, reducing the size
of the nucleus
The daughter nucleus has an atomic number 2
less and an atomic mass 4 less than the parent
nucleus
238 234 4
92 90 2
U Th + He .
Alpha Decay

12. Nuclear Decay
•Alpha Emission
He Th U
4
2
234
90
238
92

parent
nuclide
daughter
nuclide
alpha
particle
Numbers must balance!!

13. Examples of Alpha Decay

14. Occurs because the nucleus has too many
neutrons relative to protons
A neutron changes into a proton and emits an
electron
The daughter nucleus has an atomic number 1
more and an atomic mass the same as the parent
nucleus
beta Decay

15. Examples of Beta Decay

16. Occurs when a nucleus has excess energy
A gamma ray (packet of energy) is emitted
from the nucleus
The parent and daughter nuclides are the
same
The * in the reaction denotes an excited
nuclear state.
87 87
38 38
Sr* Sr + . 
Gamma Decay