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INTRODUCTION
INTRODUCTION
Radioactivity refers to the particles which are emitted from nuclei which are unstable. A nucleus that is unstable is called radioactive. A radioactive nucleus decays by emitting radiation. The radiation can be of several types, most likely alpha, beta, and gamma.
The radioactivity is the spontaneous process of decomposition of an unstable nucleus by radiating radioactive radiation.
Radioactive substances are substances with unstable nuclei in their atoms that will undergo decaying and emit radioactive radiation.
The radioactive decay is a random and spontaneous process, in which an unstable nucleus radiates radioactive radiation until the nucleus becomes more stable.
The first measurement unit of radioactivity and its symbol introduced by Marie and Pierre Curie is curie, Ci.
The S.I. unit and symbol for radioactivity is becquerel, Bq.
The half-life is the time taken for the number of undecayed nuclei reduced to half of its original value.
History of Radioactivity
History of Radioactivity
In 1895, Wilhelm Conrad Roentgen, a German physicist, discovered X-ray. He had unintentionally taken an X-ray photograph of his wife’s hand. This success led Wilhelm Conrad Roentgen to receive the first Nobel Prize in Physics in 1901 for the discovery of X-ray.
In 1896, Antoine Henri Becquerel, a French physicist, became the first person to successfully discover radioactivity. He found a radioactive compound, uranium and unintentionally produced rays that can blacken a photographic plate even in the dark. The rays were detected based on the ionising property. Due to this, Antoine Henri Becquerel received the Nobel Prize in Physics in 1903 for the discovery of radioactivity.
At the end of 1897, Marie and Pierre Curie, a married couple from Poland, successfully detected radioactive radiation through its ionising power and not through the photographic effect. Beginning with uranium ore which is known as pitchblende, they successfully extracted two radioactive elements, polonium and radium.
Atom and Nucleus
Atom and Nucleus
When an atom donates or receives an electron, the atom becomes a charged particle known as ion.
The atom that donates electrons forms a positive ions (cation).
Atom receiving electrons form negative ions (anions).
Ionising and Non-ionising Radiations
Ionising and Non-ionising Radiations
The radiation that produces positive or negative ions when crossing the air are called ionising radiation.
The radiation that not produces positive or negative ions when crossing the air are called non-ionising radiation.
Examples of ionising radiation and non-ionising radiation are shown below:
Ionising radiation
Gamma rays
Beta rays
Alpha rays
Non-ionising radiation
Radio
Infrared
Ultraviolet
Microwave
Sources of Ionising Radiation in the Environment
Natural - Cosmic rays & background radiation
Man-made - Nuclear accidents, nuclear tests, use of radioisotope for medical purposes & background radiation
Radioactive Radiations and Their Uses
Radioactive Radiations and Their Uses
Alpha rays are nuclei of helium which are positively charged. The penetrating power is low but the ionising power is high.
Beta rays are electrons which are negatively charged. The penetrating power is higher but the ionising power is moderate.
Gamma rays are electromagnetic waves which are neutral. The penetrating power is very high but the ionising power is low.
Gamma rays from cobalt-60 can be used to kill bacteria, fungi or insects in the food even after the food has already been wrapped or packed.
Radioactive substances are stored in thick lead containers surrounded by thick concrete.
Workers need to wear special protective outfits and film or photography badges to detect radioactive radiations.
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