TERM: 2ND TERM
SUBJECT: BASIC SCIENCE
CLASS: JSS 3
Meaning of Radioactivity
Radioactivity is the spontaneous disintegration or breaking down of the nucleus of an atom which makes it give out or emit radiation. Any element that disintegrates spontaneously and release rays us called a radioactive element
Discovery of Radioactivity
Radioactivity was discovered by a French physicist called Henri Becquerel in 1896. He discovered that atoms of some elements gave out some kinds of ray which penetrated a thick black paper. He used uranium for his study. His discovery was confirmed by the couple, Merie and Pierre Curie.
Types of Radioactivity
There are two types of radioactivity. i. Natural radioactivity ii. Artificial radioactivity.
Natural radioactivity occurs on its own without man's influence.
Artificial radioactivity is caused by man's activity.
Radioactive elements are elements that give out rays from the nuclei of their atoms. Natural radioactive elements include uranium, radium, plutonium, radon, thorium etc. Artificial radioactive elements are produced by bombarding nonradioactive elements (like sulphur-35, iodine-137, cobalt-60 etc.) with radioactive particles to form radioactive isotopes.
Types of Radiation and Their Properties
There are three types of rays, they are; i. Alpha particles ii. Beta particles iii. Gamma rays
Alpha particles (α-rays)
Alpha particles or rays are helium nucleus consisting of two protons and two neutrons (I.e. atomic number and atomic mass are 2 and 4 respectively).
Beta particles (β-rays)
Beta particles or rays consist of a stream of fast moving electrons.
Gamma rays (ϒ-rays)
Gamma rays are electromagnetic radiation.
The changes in the nucleus of the atom of an element caused by radioactive emission are called nuclear transmutation. For instance, Radium-226 emits -rays and turns to radon-222.
22688Ra--->42He + 22286Rn
If the changes in the nucleus are caused by man, it is called artificial nuclear transmutation.
Uses of Radioactivity
Radioactivity has application in the following fields;
In medical field
Radioactivity is used in;
In agricultural and scientific research
Radioactivity is used as;
In industrial field
Radioactivity is used to;
Effect or dangers of using radiation
Basic Science for Junior Secondary School by J.O. Otugboyega et al. Page102-103
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