Radioactivity JSS3 Basic Science Lesson Note

Radioactivity is the spontaneous disintegration of the nucleus of an atom of an element.                                                      

Radioactivity involves nucleus reactions. A chemical reaction involves the movement of an element in its nucleus, and the force holding the nucleus becomes weaker. Such an atom becomes unstable, it may break up on its own accord with the emission of energy.

The first scientist to observe spontaneous emission of radiation by uranium salt was Becquerel in 1896. Pierre and Marie Currie also isolated two new radioactive elements -1.polonium 2. radium

Radioactive elements are isotopes of elements having unstable nuclei that break spontaneously with the emission of radiation and release of large amounts of energy in achieving a stable composition Isotopes are elements with equal nuclei of protons but different numbers of neutrons in the nucleus. 

Examples of Radioactive elements are carbon 14; uranium -238, cobalt-60,uranium-235, hydrogen-3 radium -241 thorium-232, and potassium-40.

TYPES OF RADIATION AND PROPERTIES

1. ALPHA EMISSION –[α]radioactive or radioisotopes emit alpha particles which are represented [He]. The mass number  of the radioactivity isotope is reduced by 4 and the atomic number also reduced by 2 

PROPERTIES OF ALPHA EMISSION 

1. it is positively charged.          
2. it has penetrating power and can be stopped by a sheet of paper.
3. it can be deflected toward the negative plate in an electrostatic field since they are positively  
4. it has a high ionizing power.
5. it has helium particles.

2. BETA EMISSION –[β] When a radioactive isotope element emission beta particles, the atomic number is increased by 1. This does not affect the mass number. Beta particle is represented by i.e. A proton with the loss of an electron with the escape of Beta particles.

PROPERTIES OF BETA EMISSION.

1. The particle is negatively charged.
2. It has a relatively small mass.
3. They are deflected to the positive plate in an electrostatic field.
4. It has more penetrating power than alpha particles.
5. It has lower ionizing power than alpha particles. 

3. GAMMA(γ) EMISSION – gamma ray is represented by [γ] it is often emitted along alpha and beta particles  

PROPERTIES OF GAMMA EMISSION

1. Gamma rays are electron magnetic waves similar to visible light
2. it has the least ionizing power
3. it has more penetrating power than alpha & beta 
4. it causes fluorescence in sodium iodine and zinc sulfate.
5. it is unaffected by electrostatic field.

 TYPES OF NUCLEAR REACTION

1. 1. NUCLEAR FISSION –this is the breaking down or splitting of heavy radioactive isotopes to produce smaller [lighter] isotopes of other elements.
2. 2. NUCLEAR FUSION – this is when two or more light nuclei come together to form a heavy nucleus

 X-RAYS

X-rays are electromagnetic waves. They penetrate through most solid materials. Soft X-rays are used in medicine to take photographs of human body parts it is also used in the study of the arrangement of particles in crystal lattices, especially proteins.

 USES OF RADIOACTIVITY.

1. It is used to generate electricity
2. It is used in curing cancer or cancer treatment
3. In the food industry it is used to kill decay-causing bacteria and mould
4. It is used as a tracer
5. It is used in carbon dating to determine the age of a specimen        

ASSIGNMENTS.

1. 1. Gamma particles have /are  A.postively charged  B. deflected by force field C negatively charged D. most penetrating power
2. Danger of radioactive rays does not include A. destruction of body cells B. undesirable hereditary effects  C. tracer of body effects  D. death due to overexposure.
3. The radiation used to examine soft body tissue is …………. Ray  A. γ    B. β   C. α  D.X
4. Radioactivity is the spontaneous decay of the   A. nucleus   B. atom  C. electron  D. proton