First law of Thermodynamics + solved problems

Internal Energy ❒ A thermodynamic system containing some quantity of matter has within itself a definite quantity of energy. This energy includes not only the translation kinetic energy of the molecules but also other molecular energies such as rotational, vibrational energies. The kinetic and potential energy of the nuclei and …

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Work, First Law of Thermodynamics

  Nature of Heat and Work  When a change in the state of a system occurs, energy is transferred to or from the surroundings. This energy may be transferred as heat or mechanical work.  We shall refer the term ‘work’ for mechanical work which is defined as: force × distance. …

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Thermodynamic Processes

  Thermodynamic Processes ❒  When a thermodynamic system changes from one state to another, the operation is called a Process. ❒ These processes involve the change of conditions (temperature, pressure and volume). ❒ The various types of thermodynamic processes are: (1) Isothermal Processes (2) Adiabatic Processes (3) Isobaric Processes (4) …

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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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