Atomic Structure

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The three fundamental particles are: - **Electron**: Negatively charged, very light - **Proton**: Positively charged, found in nucleus - **Neutron**: Neutral (no charge), found in nucleus Their masse…

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Mass of electron = 9.109 × 10⁻³¹ kg Mass of proton = 1.673 × 10⁻²⁷ kg So, proton is approximately 1836 times heavier than the electron. This means the mass of an atom is mostly due to protons and ne…

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The neutral particle in the atom is called the **neutron**. - Discovered by James Chadwick in 1932 - Found in the nucleus - Mass ≈ 1.675 × 10⁻²⁷ kg (slightly more than proton) - No electric charge N…

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Thomson's model (1897) is also called the **plum pudding model** or **watermelon model**. - Atom is a positively charged sphere (like pudding or watermelon pulp) - Electrons are embedded in it like p…

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The aim of Rutherford's α-particle scattering experiment was to test the structure of the atom as proposed by Thomson. - Alpha particles (positively charged helium nuclei) were fired at a thin gold f…

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Rutherford's model concluded: 1. Atom has a **dense, positively charged nucleus** at its center 2. Most of the atom's mass is concentrated in the nucleus 3. Electrons revolve around the nucleus in em…

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Rutherford's model was rejected because it could not explain the **stability of the atom**. According to classical electromagnetic theory: - A charged particle (like electron) moving in a curved path…

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Electromagnetic radiation is a form of energy that travels through space as oscillating electric and magnetic fields. - These fields are perpendicular to each other and to the direction of propagatio…