Get premium membership and access revision papers with marking schemes, video lessons and live classes.

Processing. Please wait.

Radioactivity: Introduction and causes of radioactivity

Answer Text:
RADIOCTIVITY
INTRODUCTION / CAUSES OF RADIOCTIVITY
Radioactivity is the spontaneous disintegration/decay of an unstable nuclide.
A nuclide is an atom with defined mass number (number of protons and
neutrons), atomic number and definite energy.
Radioactivity takes place in the nucleus of an atom unlike chemical reactions that take place in the energy levels involving electrons.
A nuclide is said to be stable if its neutron: proton ratio is equal to one (#n/p# = 1)
All nuclide therefore try to attain #n/p# = 1 by undergoing radioactivity.
Examples
(i)Oxygen nuclide with #\ _8^16O# has 8 neutrons and 8 protons in the nucleus therefore an n/p = 1 thus stable and do not decay/disintegrate.
(ii)Chlorine nuclide with #\ _17^35Cl# has 18 neutrons and 17 protons in the nucleus therefore an n/p = 1.0588 thus unstable and decays/disintegrates to try to attain n/p = 1.
(ii)Uranium nuclide with #\ _92^237U# has 206 neutrons and 92 protons in the nucleus therefore an n/p = 2.2391 thus more unstable than #\ _92^237U#and thus more readily decays / disintegrates to try to attain n/p = 1.
(iii) Chlorine nuclide with #\ _17^35Cl# has 20 neutrons and 17 protons in the nucleus therefore an n/p = 1.1765 thus more unstable than#\ _17^35Cl# and thus more readily decays / disintegrates to try to attain n/p = 1.
(iv)Uranium nuclide with #\ _92^237U# has 143 neutrons and 92 protons in the nucleus
therefore an n/p = 1.5543 thus more stable than #\ _92^237U# but also readily decays / disintegrates to try to attain n/p = 1.
All unstable nuclides naturally try to attain nuclear stability with the production of 3 types of radiation ie alpha particle, beta particle and gamma.