this ppt includes explanation of radioactivity and radioactive rays, suitable for diploma and bachelor pharmacy students.

1. SHIKHA AGRAWAL

2. RADIOACTIVITY
 The nuclei of naturally occurring heavy elements such
as uranium, are unstable nad keep on emitting
spontaneous invisible rays and give more stable
nuclei.
 Invisible rays emmitted is known is radioactive rays .
 These invisible rays were first termed as Bacquerel
rays.
 Later it was identified as a radioactive rays.

3.  Elements which emits radioactive rays are termed as
radioactive elements.
 Phenomena of emitting these rays are termed as
radioactivity.
 Thus radioactivity is defined as
The phenomenon in which unstable nuclei undergoes
spontaneous decay and emits rays/ radiation, resulting
in the formation of a stable nuclei is known as
radioactivity.

4. DISCOVERY OF RADIOACTIVITY
 In 1896, Henry Becqueral discovered that uranium
containing crystals emits rays that could expose and
fog photographic plates.
 He proposed that uranium nuclei is unstable and it
emits energy in the form of invisible rays to become
more stable.
 The rays were identified as Becqueral rays.
 For the discovery of radioactivity ,Bacqueral was
awarded nobel prize for physics in 1903.

5.  Later in 1898, Madam Curie discovered more
radioactive elements and termed these rays as
radioactive rays.
 They shared nobel prize for discovery of radioactivity.
 Later in 1899, Ernest Rutherford describes the nature
of radiation.

6. Rutherford’s Nature Of Radiation

7. TYPES OF RADIATION
There are mainly three types of radiation :
1. Alpha rays
2. Beta rays
3. Gamma rays

8. ALPHA PARTICLE
 Positive charge particle
 High ionizing radiation
 Less penetrating power
 Similar to He atom.
 They produce flourescence.
 They are reflected by electric and magnetic field.
 Alpha decay results in decrease of atomic no. by 2
where as decrease in mass no. by 4

9. BETA PARTICLE
 They are negative charge particle.
 They have low ionization power.
 They have high penetrating power.
 Reflected by electric and magnetic field.
 Beta decay results in increase of atomic no. by 1
whereas mass number remains constant.

10. GAMMA PARTICLE
 They does not have any charge.
 Velocity is equal to velocity of light.
 They have high penetrating power.
 They have very low ionization energy.
 Emission will cause no change in mass and atomic
number.

11. Alpha particle Beta particle Gamma particle
positive charge Negative charge No charge
High ionization power Low ionization power Very low ionization power
Less penetrating power High penetrating power Very high penetrating
power .
Emission results in
decrease of atomic no by
2 and mass no. 4
Emission results in
increase of atomic no by 1
,whereas no change in
mass number.
Emission does not cause
any change in mass and
atomic no.
Similar to He atom.

12. UNITS OF RADIOACTIVITY
 Unit of radioactivity is curie.
 S.I unit of radioactivity is Becqueral.
 1 curie = 3.7 x 1010 radioactive decay per second
 1 Becqueral = 1 radioactive decay per second =2.70 x
10-11 curie.

13. Thank you