The behaviour of these particles in the magnetic or electrical field is opposite to that observed for electron or cathode rays.Some of the positively charged particles carry a multiple of the fundamental unit of electrical charge.The charge to mass ratio of the particles is found to depend on the gas from which these originate.These are simply the positively charged gaseous ions.Unlike cathode rays, the positively charged particles depend upon the nature of gas present in the cathode ray tube.Canal rays produce fluorescence when incident on zinc sulphide screen.They travel in a straight line in the opposite direction to that of cathode rays.These ions which move towards the perforated cathode kept midway in the tube and constitute the positive rays coming through the perforated cathode. When these fast-moving electrons strike the atoms or molecules of the gas present in the discharge tube, they remove one or more electrons from the neutral atoms or molecules. The cathode rays consist of a stream of high-speed electrons. When an electric discharge is passed through gas at very low pressure in the discharge tube cathode rays are produced. They are found to contain positively charged particles called protons. As they appear to arise from the anode they are called anode rays or canal rays. He found that on passing an electric discharge through a gas under reduced pressure, rays containing positive particles move towards the cathode. He performed the same experiment as performed by J.J. Actually, the spectrum observed is line spectrum of definite frequency, and hence a modification of Rutherford’s atom model was necessary. Thus it should move in a spiral path and should emit continuous spectrum and thus structure atom is not stable. therefore, it should approach nearer the nucleus while going round emitting radiations of increasing frequency and finally falling in the nucleus. Therefore, theĮlectron should radiate energy while going round the nucleus losing its energy continuously. The negatively charged electrons revolve around the nucleus in a circular orbit, hence they possess centripetal acceleration. According to the classical theory of electromagnetism, accelerated charge radiates energy continuously.Limitations Of Rutherford’s Atomic Model: Rutherford’s model of an atom is also called as a planetary model of an atom. Around the nucleus, there is empty space in which the negatively charged electrons revolve in different orbits. The whole mass of an atom is concentrated in the nucleus. The atom consists of the centrally located positively charged nucleus. The rest of the portion of the atom should be empty.įrom the observations of his experiment, Rutherford put forward the concept of his atomic model.
He called this centrally cored and positively charged region of an atom as a nucleus. It is due to the positive charge present in a very small space within the atom.
Hence there must be empty space in the atom.
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