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group displacement law
i. When an element emits a-particle,
When an element emits b-particle,
iii. During g-emission, A and Z remain the same.
The number of atoms disintegrated per unit time is a
constant fraction of the total number of the atoms present at that
or disintegration constant (l)
The fraction of the total number of atoms (nuclei) undergoing
radioactive disintegration per unit time is called decay or
disintegration constant of the element.
- d N/N
Or l =
N0 = total number of radioactive atoms
initially present (t = 0).
Nt = total number of radioactive atoms
present at time t.
The time required for the disintegration of a
radioactive element to reduce to half of the original amount is
called half-life period.
The process of conversion of a stable isotope of one element
into a stable isotope of another element by bombarding it with
suitable high energy (nuclear) particles is called artificial
The atomic nucleus which is bombarded by high energy
nuclear particles (projectiles) is called a target.
The high energy nuclear particles such as a-particle,
proton or neutron, which are used to bombard an isotope of an element are called projectiles.
or recoil nucleus
The new atom produced from the target nucleus after it
is bombarded with projectiles and which has a mass number not far
different from that of target, is known as product or recoil nucleus.
The particles which are ejected from the target nucleus
after bombardment with projectiles are called emissions.
The spontaneous emission of radiation from the nuclei of
heavy elements is called natural radioactivity.
The phenomenon of conversion of a stable nucleus
(non-radioactive) into an unstable radioactive nucleus by artificial
disintegration is called artificial radioactivity.
of artificial transmutation of elements using various projectiles
A) Using a-particles
B) Using deuterium nuclei
C) Using protons
D) Using neutrons
of nuclear reactions
The naturally unstable elements which spontaneously emit
some radiations like a-particles, protons, neutrons, g-rays, etc.
are called as radioisotopes.
Radio isotope dating was developed by W. F. Libby.
isotope of carbon (a beta emitter), the age of
archaeological materials containing
matter of living
origin can be found.
(in the form of NaCl) ® to study
diagnose and treat thyroidal disorders.
® to treat leukaemia.
® to treat
certain types of cancers.
® to stop
the growth of cancer.
® to study
plant metabolism and to syudy the usefulness of phosphorus
® to study photosynthesis
® to find
out the uptake of calcium by the plants from the soil.
Production of synthetic elements