Pauli’s Exclusion Principle

  Pauli’s Exclusion Principle ❒  The nature of an electron, its position and energy, is fully implied only by mentioning the values of four quantum numbers ascribed to it. ❒ Each electron is, therefore, fully characterised by a set of four quantum numbers (n) – giving the size of electron …

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Quantum Numbers

  Quantum Numbers ❒ Bohr’s electronic energy shells or levels, designated as Principal Quantum Numbers (n), could hardly explain the hydrogen spectrum adequately. Spectra of other elements that are quite complex, also remained unexplained by this concept. ❒ Many single lines of the spectra are found to consist of a …

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Schrödinger’s Wave Equation

  Schrödinger’s Wave Equation ❒ In order to provide sense and meaning to the probability approach, Schrödinger derived an equation known after his name as Schrödinger’s Wave Equation.  ❒ Calculation of the probability of finding the electron at various points in an atom was the main problem before Schrödinger.    ❒ His …

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Heisenberg’s uncertainty Principle

  Heisenberg’s uncertainty Principle ❒One of the most important consequences of the dual nature of matter is the uncertainty principle developed by Werner Heisenberg in 1927. ❒ This principle is an important feature of wave mechanics and discusses the relationship between a pair of conjugate properties (those properties that are …

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Zeeman Effect

  Zeeman Effect ❒ In 1896 Zeeman discovered that spectral lines are split up into components when the source emitting lines is placed in a strong magnetic field. It is called the Zeeman effect after the name of the discoverer. ❒ The apparatus used to observe Zeeman effect is shown …

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Bohr Model Of The Atom

  ❒ Rutherford’s nuclear model simply stated that atom had a nucleus and the negative electrons were present outside the nucleus. It did not say anything as to how and where those electrons were arranged. It also could not explain why electrons did not fall into the nucleus due to …

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Photoelectric Effect and Compton Effect

  Photoelectric Effect ❒When a beam of light of sufficiently high frequency is allowed to strike a metal surface in vacuum, electrons are ejected from the metal surface. This phenomenon is known as Photoelectric effect and the ejected electrons Photoelectrons.  ❒For example, when ultraviolet light shines on Cs (or Li, …

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Atomic Spectrum of Hydrogen

  Atomic Spectra ❒When an element in the vapour or the gaseous state is heated in a flame or a discharge tube, the atoms are excited (energised) and emit light radiations of a characteristic colour. The colour of light produced indicates the wavelength of the radiation emitted.       …

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Atomic Number – Mass Number

  Mosley’s Determination of Atomic number ❒ The discovery that atom has a nucleus that carries a positive charge raised the question : What is the magnitude of the positive charge? This question was answered by Henry Mosley in 1913. ❒ Hitherto atomic number was designated as the ‘position number’ …

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