ATOMIC STRUCTURE
SCIENTISTS AND THEIR DISCOVERIES:
1858 Plucker : Experiments with discharge tube.
1876 Goldstain : Gave the name cathode rays.
1879 Crookes : Found cathode rays have mass.
1891 Jhonson Stoney : Gave the name electron.
1895 Jean Perrin : Proved Cathode rays have -ve charge.
1897 J. J. Thomson : Found e/m ratio of cathode rays constant.
1895 W.C. Rontgen : Discovered x-rays.
1909 Millikan : Determined charge of electrons by Oil drop method.
1886 Goldstain : Discovered +ve rays and protons
1911 Rutherford : Discovered Nucleus
1932 Chadwick : : Discovered Neutrons
1935 Yukawa : Discovered Meson (∏)
1932 C.D., Anderson : Discovered Positron
1927 Pauli : Discovered Neutrino
1955 Segre : Antiproton
1900 Max Planck : Quantum Theory
1903 Einstein : Modified Planck’s theory
1913 Niels Bohr : Structure of ‘H’ atom
1924 Leuis De Broglie : Dual Nature to electron.
1927 Heisenberg : Uncertainity Principle.
1912 Moseley : At.No. By studying x-ray frequency
Schrodinger : Wave Mechanical concept.
Hund : Rule of multiplicity.
STATISTICS
e/m of cathode rays : 1.76 x 108 coulombs/gm or 5.28×1017 e.s.u/gm
Charge of electron : 1.602 x 10-19 coulombs
= 1 unit electricity or 4.808 x 10-10 e.s.u.
Rest mass of electron : 9.11 x 10-28 gms. Or 0.0005486 amu
Radius of electron : 2.8 x 10-13 cms.
Density of electron : 2.17 x 1017 g/cc
Charge of 1 mole of electron : 96500 coulombs = 1 Faraday = 2.86 x 1014 esu.
Mass of 1 mole of electron : 0.55 mg. = 55 x 10-4 gms. = 3.304 x 1020 amu.
Average mass of H Atom : 1.675 x 10-24 gms.
Mass of Proton : 1.672 x 10-24 gms or 1.00758 amu.
Gold foil used by Rutherford : 0.00004 cms thickness.
Charge of α-rays : 3.2 x 10-19 coulombs.
Mass of α-rays : 6.6 x 10-24 gms.