Structure of Atom

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According to Dalton's atomic theory (1808), an atom is the ultimate particle of matter that cannot be divided further. The word 'atom' comes from the Greek word 'a-tomio' which means 'uncut-able' or '…

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The three fundamental subatomic particles are: 1. Electron (e⁻): Negatively charged, mass = 9.109 × 10⁻³¹ kg, charge = -1.602 × 10⁻¹⁹ C 2. Proton (p⁺): Positively charged, mass = 1.673 × 10⁻²⁷ kg, cha…

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Thomson's cathode ray tube experiment (1897) involved passing electricity through a partially evacuated glass tube with electrodes. Key observations: - Rays traveled from cathode to anode - Rays were …

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The charge-to-mass ratio of an electron is e/mₑ = 1.758820 × 10¹¹ C/kg. It was determined by J.J. Thomson using perpendicular electric and magnetic fields in a cathode ray tube. By balancing these fie…

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Millikan's oil drop experiment (1906-14) determined the charge on an electron: - Oil droplets were suspended between charged plates - X-rays ionized the air, giving droplets electric charge - By adjus…

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Thomson's model (1898) proposed that: - An atom is a uniform sphere of positive charge (radius ~10⁻¹⁰ m) - Electrons are embedded in this positive sphere like plums in a pudding - The arrangement give…

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Rutherford's α-particle scattering experiment (1909): Setup: High-energy α-particles bombarded thin gold foil with fluorescent screen around it Observations: - Most α-particles passed through undeflec…

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Rutherford's nuclear model features: 1. Most of the atom's space is empty 2. Positive charge and most mass concentrated in a tiny nucleus (radius ~10⁻¹⁵ m) 3. Electrons revolve around nucleus in circu…