RADIOACTIVITY

                                 

Description:

The elements having charge number z greater than 82 are unstable. They emit invisible radiation which effect the photographic plate. Such element  are called radioactive elements and the process is called Radioactivity. The radiations emitted by radioactive elements are of three types named as alpha Beta and g. Radioactivity is a purely nuclear phenomenon. It is not affected by physical or chemical reaction. Radioactivity does not depend upon physical state of the radioactive material such as temperature, pressure, density etc.


Discovery:
Radioactivity was discovered by Henri Becquerel in 1896. He found that an ore containing uranium {z = 92} emits an invisible  radiation which penetrates through a black paper wrapping a photographic plate and effects the plate.
Conclusion:
From this experiment we conclude that: 1) All radiations from radioactive material are not alike (same). (2) The radiations bending towards the negative plate are positively charged particles; called a-particles (3) The radiations bending towards the positive plate are negatively charged particles, called p-particles (4) The radiations that go straight without bending have no charge on them. These are called g-rays

a-Particles:
They are helium nuclei. Each a-particle has 2-protons and 2-neutrons charge number
2 2 mass number A 4

B-Particles:

They are fast moving electrons (i.e.) coming out of nucleus.  charge number Z-1 mass number then from A o
 Y-Rays:
Like x-rays, y-rays are electromagnetic rays coming out of nucleus. The wavelength

of y-rays is mu than the X-rays. They have very high frequency.