Structure of an atom1/5/2023 ![]() ![]() Most of the α- particles passed through gold foil un deflectedī. Observations from α- particles scattering experiment by Rutherford:Ī. This model proposed that atom is considered asa uniform positively charged sphere and electrons are embedded in it.An important feature of Thomson model of an atom was that mass of atom isconsidered to be evenly spread over the atom.Thomson model of atom is also called as Plum pudding, raisin pudding orwatermelon model Thomson model of atom was iscarded because it could not explain certainexperimental results like the scattering of α- particles by thin metal foils. M ass Number (A) :Sum of the number of protons and neutrons present in thenucleus. They are electrically neutral particles having a mass slightly greater than that of the protons.Ītomic number (Z) : the number of protons present in the nucleus(Moseley1913). Were discovered by James Chadwick by bombarding a thin sheet of beryllium by α- particles. Behaviour of positively charged particles in electrical or magnetic field is opposite to that observed for cathode rays Some of the positively charged particles carry a multiple of fundamental of electrical charge.d. The positively charged particles depend upon the nature of gas present in the cathode ray discharge tubeĬ. Charge to mass ratio of particles depends on gas from which these originateb. Modified cathode ray tube experimentwas carried out which led to the discovery of protons.Ĭharacteristics of positively charged particles:Ī. The mass of anelectron was determined to be 9.1094 x 10 -31kg. The mass on an electron was determined by combining the results ofThomson’s experiment and Millikan’s oil drop experiment. The value of the charge on an electron is -1.6 x 10 -19C. ![]() C kg -1Ĭharge on an electron was determined by R A Millikan by using an oil dropexperiment. The chargeto mass ratio of an electron as 1.758820 x 10 11. Material of the electrodes and the nature of the gas present in the cathode ray tube.Ĭharge to mass ratio of an electron was determined by Thomson. The characteristics of the cathode rays do not depend upon the In presence of electrical or magnetic field, behaviour of cathode rays is similar to that shown by electronsĮ. In absence of electrical or magnetic field cathode rays travel in straight linesd. Cathode rays themselves are not visible but their behavior can be observed with help of fluorescent or phosphorescent materials.Ĭ. Cathode rays consist of negatively charged electrons.ī. Perforatedanode was taken, the cathode rays struck the other end of the glass tube atthe fluorescent coating and a bright spot on the coating was developedĪ. At very low pressure and high voltage,current starts flowing through a stream of particles moving in the tube fromcathode to anode. Nucleus was discovered by Rutherford in 1911.Ĭathode ray discharge tube experiment: A cathode ray discharge tube madeof glass is taken with two electrodes. Electrons were discovered using cathode ray discharge tube experiment. ![]()
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