Explain the discovery of sub-atomic particles :
a. Proton
b. Neutron
c. Electron
Answers
Answer:
ELECTRON :-
The Electron was discovered in 1896, by the British physicist J. J. Thomson, using a cathode rays while doing discharge tube experiments. Thomson also determined e/m, ratio of the charge e to the mass m of the material particle which constituted these rays. Note that the first clues that the electron existed were first noticed by German physicist Johann Wilhelm Hittorf in 1869 when he discovered that the glow emitted from the cathode that increased in size with decrease in gas pressure. Hittorf was studding the electrical conductivity in rarefied gases.
The particle first named "corpuscles" by Thomson, it was later renamed "Electron" by a proposal of Irish physicist George F. Fitzgerald that has gained universal acceptance.
PROTON :-
Protons are positively charged particles that reside in the nucleus of an atom. These protons add the overall positive charge of a molecule. The mass of the proton is about 1,840 times the mass of the electron.
Through scientific discovery, protons have been accepted as the particle that contributes to the positive charge of an atom. The discovery of protons can be attributed to Rutherford.
In 1886 Goldstein discovered existence of positively charged rays in the discharge tube by using perforated cathode. These rays were named as anode rays or canal rays.
In 1899, Rutherford discovered alpha and beta ‘rays’ from uranium. He later demonstrated that alpha rays are the nuclei of helium atoms. He discovered in 1914 that the nucleus of an atom constituted and extremely dense but small fraction of the volume of an atom and that this nucleus was positive in charge.
NEUTRON :-
It is remarkable that the neutron was not discovered until 1932 when James Chadwick used scattering data to calculate the mass of this neutral particle. Since the time of Rutherford it had been known that the atomic mass number A of nuclei is a bit more than twice the atomic number Z for most atoms and that essentially all the mass of the atom is concentrated in the relatively tiny nucleus. As of about 1930 it was presumed that the fundamental particles were protons and electrons, but that required that somehow a number of electrons were bound in the nucleus to partially cancel the charge of A protons. But by this time it was known from the uncertainty principle and from "particle-in-a-box" type confinement calculations that there just wasn't enough energy available to contain electrons in the nucleus.
Answer:
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Explanation:
a) Proton- protons are subatomic that, with neutrons and electrons, are the principle constitutents of the atom.
b) Neutron - Neutrons were discovered by James Chadwick in 1932, when he demonstrated that penetrating radiation incorporated beams of neutral particles.
c) Electron - After many experiments involving cathode rays J.J Thomson demonstrated the ratio of mass to electric charge of cathode rays.