Discovery of Proton
The formation of cathode rays has shown that all the atoms contain negatively charged particles called electrons. Now, an atom is electrically neutral,so it must contain some positively charged particles to balance the negative charge of electrons. It has actually been found by experiments that all the atoms contain positively charged particles called protons.
The existence of protons in the atoms was shown by E.Goldstein.When Goldstein passed electricity at high voltage through a gas at very low pressure taken in a discharge tube, streams of heavy particles were given out by the anode (positive electrode).These streams of particles are called anode rays. Anode rays consist of positively charged particles.The mass and charge of the anode ray particles depends on the nature of gas taken in the discharge tube.Different gases give different types of anode rays which contain positively charged particles having different masses and different charges.
Hydrogen gas is the lightest gas and hydrogen atom is the lightest atom.So,the positive particles obtained from hydrogen gas are the lightest and have the smallest charge. The anode rays obtained from hydrogen gas are made up of the same type of positive particles. These particles are called protons. Thus,the anode rays obtained from hydrogen gas consist of protons.A proton is formed by the removal of an electron from a hydrogen atom.
Goldstein explained the formation of protons as follows.Hydrogen gas consists of hydrogen atoms.When high electrical voltage is applied to hydrogen gas,the electrical energy removes the electrons from the hydrogen atoms. After the removal of negatively charged electron from a hydrogen atom, a positively charged particle called proton is formed. These fast moving protons form the anode rays.Please note that hydrogen atoms are the lightest of all the atoms, so hydrogen atoms form the lightest positively charged particles called protons. The heavier atoms of other gases form heavier positively charged particles which are made up of a number of protons held together. We can now define a proton as follows.
The proton is a positively charged particle found in the atoms of all the elements.The protons are located in the nucleus of an atom.Only hydrogen atom contains one proton in its nucleus, atoms of all other elements contain more than one proton.A proton is usually represented by the symbol p+ (p for proton and plus sign for positive charge).
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Structure of the Atom - Notes
1. Drawback of Rutherford’s Model of the Atom
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2. Rutherford’s Experiment - Discovery of Nucleus
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3. For the symbols H, D and T,tabulate three sub-atomic particles found in each of them.
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5. Structure of The Atom - Study Points
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10. Arrangement Of Electrons In The Atoms
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12. Limitations of Rutherford's model of the atom
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16. All about Names of the Chemical Elements
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17. How to learn naming Chemical Formulae?
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21. Comparison between Proton, Neutron and Electron
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22. Electronic Configurations of First 20 Elements
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26. Rules for writing of distribution of electrons in various shells for the first 18 elements
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36. The Physical Properties of the Isotopes of an Element are Different
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39. All the Isotopes of an Element Have Identical Chemical Properties
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42. Relationship Between Mass Number and Atomic Number
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44. Valaence Electrons (Or Valancy Electrons)
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45. Electronic Configurations of Noble Gases (or Inert Gases)
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48. Reason for the Fractional Atomic Masses of Elements
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49. Applications of Radioactive Isotopes
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