I hope this is useful to you,just understand the article

1. RADIOACTIVITY

2. Contents:
 Introduction
 Radioactive Rays
 Properties of Rays
 Radioactive Decay
 Units of Radioactivity
 Radioactive Equilibrium
 Group Displacement Law

3. Introduction
 In 1895,Henri Becquerel concluded that
uranium salts emitted certain rays which had
penetrating properties similar to X-rays.
 These rays also ionization of air, the property
of emission of these rays as radioactivity.
 In 1896 Marie Curie discovered Polonium
element from it’s uranium mineral pitchblende.
 Two years later, they discovered another
element Radium from the same mineral.

4. Properties of Alpha rays
 Positive charged particle
 Deflected by electric and magnetic field
 Affects photographic plates and cause
fluorescence
 Produce strongest ionisation
 Least penetrating power( stapped by a sheet
of paper)
 Biggest mass and charge
 Can travel 2-4cm
 +2e charge value

5. Properties of Beta rays
 Negative charged particle
 Deflected by electric and magnetic field
 Affects photographic plates and cause
fluorescence
 Produce less ionisation than alpha particle
 Can penetrate clothes,skin,paper (stapped by
aluminium sheet)
 Smallest mass and charge
 Can travel 2-3m
 e- charge value

6. Properties of Gamma rays
 Electromagnetic waves like-light or X-ray
 Remains undeflected by electric and magnetic field
 Affects photographic plates and cause
fluorescence
 Produce little or no ionisation
 Most penetrating power than alpha and beta rays
 Smallest mass and charge
 Can travel 500m
 0 charge value

7. Radioactive Decay
 Radioactive decay is a spontaneous
phenomenon of emission of particle or
electromagnetic radiation from an atomic
nucleus.
 The high molecular weight elements are emitts
radioactive rays spontaneous.
 n/p=1 ->the atom is stable
 >1 ->the no.of.neutrons high
 <1 -> the no.of.protons high

8. Units of Radioactivity
 The Units of radioactivity called curie(ci),is
defined as the amount of a radioactive
substance which has a decay rate of
3.7*10^10 disintegration per second.
 The units millicurie(mci) and microcurie.
 1mci = Mass which gives 3.7*10^10
disintegrations s^-1

9. Radioactive Equilibrium
When equilibrium exists, the activity of the
daughter is decreasing according to the parent,
Three cases are concluded:
1.Secular Equilibrium(T1>>T2).
2.Transient Equilibrium(T1>T2), the half-life
of the parentis longer than that of the daughter.
3.No Equilibrium(T1<T2),the half-life of the
parent is shorter than that of the daughter.

10. Group Displacement Law
 The emission of an alpha particle results in the
formation of an element which lie two places to
the left.
 The emission of a beta particle results in the
formation of an element which lies one place to
the right in the periodic table.
 When atom emitted gamma particle that atoms
are expelled energy then atom becomes more
stable.