Discovery of electrons from structure of atom.pptx

Discovery of electrons from structure of atom.pptx

1. STRUCTURE OF ATOM Archa S R BEd Physical Science

2. ELECTRONS Electrons are subatomic particles. They are negatively charged particles. The ratio of electrical charge to mass of an electron was determined by J J Thomson. J J THOMSON

3. PLUM PUDDING MODEL OF ATOM J J Thomson proposed his plum pudding model of atom, It is also known as watermelon model, J J Thomson’s model etc. According to this model negatively charged electrons are embedded in a positively charged sphere. The total number of positive charges and negative charges in the sphere will be equal, so atom is electrically neutral. This model failed to give explanations to several experiments hence it was rejected.

4. DISCOVERY OF PROTON

5. EUGEN GOLDSTEIN In 1886 Eugene Goldstein conducted discharge tube experiments that led to the discovery of canal rays.

6. In this discharge tube experiment, the cathode taken was perforated. The rays originate from anode are called anode rays or Canal rays

7. He studied the characteristics of these rays and identified the presence of positive charge in them. The behaviour of canal rays varied with the nature of gases taken in the discharge tubes. The smallest and lightest positive particles in the canal rays were obtained when the discharge tube was filled with hydrogen. Later, Earnest Rutherford discovered that this was a subatomic particle and named it proton.

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