Wednesday, August 19, 2009

Radioactive Emissions

Properties of radioactive emissions:

A) Structure and Charge

1. Alpha particle
an alpha particle is the nucleus of helium atom and made up of two protons and two neutrons. it is positively charged (+2).

2. Beta particle
A beta particle is a fast moving electron and has a negative charge (-1).

3. Gamma ray
Gamma ray is an electromagnetic wave; it moves at the speed of light, c ( 3x10^8 m/s). Gamma ray does not carry any charge.

Alpha and beta particles have opposite charges, thus they are deflected in opposite directions.
Gamma ray is neutral , thus it is not deflected by the magnetic field.

B) Ionising Power and Penetrating Power


Alpha particle have a relatively high ionising power and hence a relatively low penetrating power. on the other hand, gamma ray which has a relatively low ioning power has a realatively high penetrating power.

alpha particles can be stopped by a piece of paper, beta particles are stopped by a few centimetres aluminum sheets, while gamma ray can only be stopped by a few centimetres of lead.

Particles that ionise other atoms strongly have a low penetrating power because they lose energy each time they ioning an atom.

Spontaneous radioactive emissions are not affected by external conditions like temperature and pressure.

Summary

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