General Chemistry

Reactivity of the Substrate in SN2 Reactions

Reactivity of the Substrate in SN2 Reactions

Reactivity of the Substrate in SN2 Reactions – We will often refer to the alkyl halide as the substrate: literally, the compound that is being attacked by the reagent. – Just as the nucleophile is important in the SN2 reaction, the structure of the alkyl halide is equally important. – …

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Molecular Orbital Theory

  Molecular Orbital Theory ❒ Molecular orbital theory proposed by Hund and Mulliken in 1932 explains the formation of a covalent bond in a better way.  ❒ According to molecular orbital theory all atomic orbitals of the atoms participating in molecule formation get disturbed when the concerned nuclei approach nearer. …

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Electron Affinity and Electronegativity

  Electron Affinity  ❒ A neutral atom can accept an electron to form negative ion. In this process, in general, energy is released.  ❒ Electron affinity (EA) of an element: is the amount of energy released when an electron is added to a gaseous atom to form an anion.   …

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Ionization Energy

  Ionization Energy ❒ The process of removing an electron from an isolated atom to form a positive ion is called ionisation. Energy will be required to remove an electron from the atom against the force of attraction of the nucleus. ❒ The ionisation energy (IE) of an element: is …

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Electron Configuration Of Elements

  Electron Configuration Of Elements ❒ We have seen before that to define completely the state of an atom it is obligatory to refer to all the four quantum numbers (n, l, m and s) of every electron in it. ❒ Since a simultaneous representation of all quantum numbers of …

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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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