Carbon Dating
Carbon dating W.F. Libby (1950)has shown that by measuring the radioactivity of it is possible to calculate the date at which a plant was cut or an animal died. The principle of this technique is that is produced in the upper atmosphere as: There is one atom of for every carbon atom in the of the atmosphere and in all living animals and plants. This ratio always remains constant in nature. when the animal or plant dies starts disintegration as: Thus by measuring the radioactivity of the substance under consideration...
read moreNuclear Binding Energy
Nuclear binding energy It may be defined as the energy released when the given number of protons and neutrons combine to form its nucleus. In other words, it is the energy required to disrupt its nucleus into its constituents. This released energy corresponds to mass defect , e.e., the difference between the expected mass and the actual mass of the atoms. It may be written as: Binding energy = [mass of neutrons + mass of protons + mass of electron] of the atom – actual mass of the atom = mass defect a.m.u. 931.5 × Mass defect (MeV) (since 1...
read moreNuclear Fission and Fusion
Nuclear fission and fusion The nuclear fission may be defined as the splitting of a heavy nucleus into nearly two equal parts by the bombardment of slow neutron with the release of energy. Otton Hahn and Strassmann (1939) carried out first nuclear fission reaction as: In this process the emitting neutrons bombard again on and a chain reaction may be set up. In this way a huge amount of energy is liberated. This process is used in atom bomb and in atomic reactors. The process in which lighter nuclei fuse together to produce heavier...
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Nuclear reactions Possible by using projectiles like (Deutron) etc. Ex. Cyclotron [discovered by E.O. lawrance] increase kinetic energy of -projectile to increase their speed and projectile power. Synchrotron does some work for...
read moreArtificial Radioactivity
Artificial (Induced) Radioactivity I.Curie and F. Joliot (1934) introduced a new term, i.e., artificial radioactivity during the study of the following nuclear reaction: (positron) In this process radioactive phosphorus is prepared artificially, which further disintegrates. They also used isotopes and obtained radioactive respectively. Now-a-days proton, deutron, neutron etc are also used as projectiles and different emitting particles are...
read moreIsobars
Isobars Isobars are atomic species having the same mass number but different atomic number e.g. etc. they differ in chemical properties, however physical properties related to mass are same Isotones are atoms having same number of neutrons but different mass number e.g. . (All have 16 neutrons). Isomers (nuclear) are atoms having the same mass number and same atomic number but with different radioactive properties e.g. . The above four terms may be summed up as: Term No. of Protons No. of Neutrons Mass...
read moreIsotopes
Isotopes Discovered by Soddy; atoms of a given element which differ in atomic mass but have same atomic number are called isotopes. For example are the isotopes of chlorine; are the isotopes of hydrogen. Isotopes have same chemical properties; however rate of reaction many differ. The fractional atomic weight of the atoms is due to isotopes e.g. the isotopes of neon are which are present in the ratio 9 : 1. Hence its atomic weight Heavier isotope is radioactive e.g. C-212, C-14...
read moreRadioactive Equilibrium
Radioactive Equilibrium In radioactive transformation when a daughter element transforms at the same rate at which it is formed from the parent element that state is known as radioactive equilibrium e.g. parent intermediate daughter At equilibrium Or, Example 1: disintegrates to give as the final product. How many alpha and beta particles are emitted during this process? Solution: in this process change in at. Wt. =234 – 206 = 28 a.m.u. since by the emission of one -particle m. no. decreases by 4 units hence no. of emitted...
read moreRadioactive Disintegration Series
Radioactive Disintegration Series Since radioactive disintegration is a continuous process hence a series can be drawn which is known as radioactive disintegration series. There are four such series: (i) Thorium series (4n series) begins with and ends at . [Mass is fully divided by 4] (ii) Neptunium series (4n + 1series) begains with . [here reminder is one] (iii) Uranium series (4n + 2 series) begins with . [here reminder is 2] (iv) Actinium series (4n + 3 series) begins with . [here reminder is 3] Number of -particles emitted during these...
read moreUnits of Radioactivity
Units of radioactivity There are three units (Becquerel, curie and Rutherford) of radioactivity. Curie (Ci) is defined as that quantity of any radioactive substance which gives disintegration (dps). Rutherford (rd) is defined as the amount of radioactive substance which gives disintegrations (dps). Rutherford In SI system, the unit of radioactivity is Becquerel (Bq) 1 Bq = 1 dps = 37...
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