1. Radioisotopes

2. Atomic structure
(N)
(Z)
A = Z + N

3. Isotope
Isotopes are any of the different types of atoms (Nuclides) of the same chemical element, each having a different atomic mass (mass number)
Isotopes of an element have nuclei with the same number of protons (the same atomic number) but different numbers of neutrons.
Therefore, isotopes have different mass numbers, which give the total number of nucleons, the number of protons plus neutrons.

4. Isotope
About 339 nuclides occur naturally on Earth, of which 250 (about 74%) are stable.
Counting the radioactive nuclides not found in nature that have been created artificially, more than 3100 nuclides are currently known

5. Isotope
Elements are composed of one or more naturally occurring isotopes, which are normally stable.
Some elements have unstable (radioactive) isotopes

6. Isotope

7. Isotope Some isotopes are stable, others are unstable or radioactive
Radiation is emitted when an unstable nucleus spontaneously changes, or disintegrates into more stable one.
Every element in the periodic table has at least one radioactive isotope.
Radioactivity is a form of nuclear reaction (nucleus) not chemical reaction (electrons)

8. Nuclear and chemical reactions
A nuclear reaction involves changes in an atom’s nucleus, usually producing a different element. Chemical reaction never changes the nucleus, it only rearranges the outer shell electrons.
Different isotopes of an element have essentially the chemical reactivity (same electrons), but often have completely different behavior in nuclear reactions.

9. Nuclear and chemical reactions
The rate of nuclear reaction is not affected by the change in temperature, pressure or addition of a catalyst, or the chemical form (compound or element).
The energy change accompanying a nuclear reaction can be several million times greater than that of a chemical reaction.

10. Radioactive decay
Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation.
This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide.

11. Radioactivity
Nuclear decay or Radioactivity is the spontaneous emission of radiation from a nucleus.
One element can change into another element via radioactive decay or transmutation
Discovered by Henry Becquerel in 1896.
He concluded that uranium gave off some radiation.

12. Radioactivity
The radiation or radioactivity was later shown to be separable by electric (and magnetic) fields into three different types:
Alpha (a); a helium nucleus, He2+, emitted as alpha particle.
Beta (b); an electron emitted from the nucleus
Gamma (g); radioactivity consisting of high-energy light waves.

13. Radioactivity Half-Life
Nuclear decay is a first order process 
Rates of nuclear decay are measured in units of half life (t1/2), defined as the time required for one half of the radioactive sample to decay.
Isotope
Particle type
Half life 3H b-
12.3 yr
14C
5570 yr
32P
14 days
22Na
b- & g
15 hr
125I g
60 days
131I
8 days
238U a
>billions yrs

14. Units of Radiation
The SI unit of radioactive decay (the phenomenon of natural and artificial radioactivity) is the becquerel (Bq).
One Bq is defined as one transformation (or decay) per second.

15. Units of Radiation
In the meteric system, radioactivity unit is Becquerel (Bp); 1 Bp= 1 disintegration per second (dps).
The basic unit of radioactivity is Curie (Ci), and its subdivisions: mCi, mCi
The two units can be interconverted:
1 Ci= 3.7 x 1010 Bp or dps.

16. Units of Radiation
Instruments (b or g counters) report radiation as cpm or (count per minute).
cpm = dpm * (counting efficiency of machine)
dpm= disintegration per minute