chapteer 2

1. 1- [blank_start]Spectroscopy[blank_end] is the study of the interaction of light with matter.
   There
   are two distinct aspects of this interaction that can be used to learn
   about atoms and molecules.
   1) specific wavelengths of light that interact with the atoms and molecules.
   2) measurement of the amount of light absorbed or emitted at specific wavelengths.

   1. ASpectroscopy
2. 2- [blank_start]Infrared spectroscopy[blank_end] is particularly useful for studying the vibration
   of bonds between carbon, hydrogen, oxygen and nitrogen atoms that
   predominate in organic compounds.
   can indicate the presence of particular functional groups in unknown
   organic compounds by the presence of characteristic features.

   1. AInfrared spectroscopy
3. 3The total energy of a molecule is the sum of its [blank_start]electronic[blank_end], its
   [blank_start]vibrational[blank_end] energy and its [blank_start]rotational[blank_end] energy.

   1. Aelectronic
   2. Brotational
   3. Cvibrational
4. 4• Near-IR, approximately [blank_start]14000[blank_end]-[blank_start]4000[blank_end] cm-1 can excite overtone or
   [blank_start]harmonic[blank_end] vibrations
   • Mid-IR, approximately [blank_start]4000[blank_end]-[blank_start]400[blank_end] cm-1 may be used to study the
   [blank_start]fundamental[blank_end] vibrations and associated rotational-vibrational
   structure
   • Far-IR, approximately [blank_start]400[blank_end]-[blank_start]10[blank_end] cm-1 lying adjacent to the
   microwave region, has low energy and may be used for [blank_start]rotational[blank_end]
   spectroscopy

   1. A14000
   2. B4000
   3. Charmonic
   4. D4000
   5. E400
   6. Ffundamental
   7. G400
   8. H10
   9. Irotational
5. 5vibrational transition from the ground state to the first excited
   state due to absorption of infrared light is called a [blank_start]fundamental absorption[blank_end] and the frequency, v, associated with this is called the
   [blank_start]fundamental[blank_end] frequency

   1. Afundamental
   2. Bfundamental absorption
6. 6[blank_start]Stretching[blank_end] vibrations: In this type of vibrations, the bond length is increased or
   decreased at regular intervals. There are two types of stretching vibrations:
   Symmetrical stretching and asymmetrical training (Figure 2.4).
   a) [blank_start]Symmetrical[blank_end] stretching: In this type of stretching, bond length increase or decrease
   symmetrically.
   b) [blank_start]Asymmetrical[blank_end] stretching: In this type of stretching, length of one bond increases and the
   other one decreases.

   1. AStretching
   2. BSymmetrical
   3. CAsymmetrical
7. 7[blank_start]Bending[blank_end] vibration: In this type of vibrations, a change in bond angle occurs between bonds with a common atom, or there is a movement of a group of atoms with respect to the remainder of the molecule without movement of the atoms in the group with respect to one
   another
   it is also called [blank_start]deformation[blank_end] vibrations
   two types
   a) [blank_start]In-plane[blank_end] bending vibration: In these types of vibrations, there is a change in
   bond angle. This type of bending takes place within the same plane. In plane
   bending are of two types:
   i) [blank_start]Scissoring[blank_end] in which bond angle decreases.
   ii)[blank_start]Rocking[blank_end] in which the bond angle is maintained but both bonds moves
   within the same plane.
   b) [blank_start]Out-of-plane[blank_end] bending vibration: This type of bending takes plane outside of the plane of molecule:
   i)[blank_start]Wagging[blank_end] in which both atoms move to one side of the plane
   ii) [blank_start]Twisting[blank_end] in which one atom is above the plane and the other is below
   the plane.

   1. Adeformation
   2. BBending
   3. CIn-plane
   4. DScissoring
   5. ERocking
   6. FOut-of-plane
   7. GWagging
   8. HTwisting
8. 8Significant for the identification of the source of an absorption band are [blank_start]intensity[blank_end] (weak, medium or strong), [blank_start]shape[blank_end] (broad or sharp), and [blank_start]position[blank_end] (cm-1) in the spectrum.

   1. Aintensity
   2. Bshape
   3. Cposition

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first Loll Test sobre chapteer 2, creado por Manar Sherbeny el 21/06/2021.

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Manar Sherbeny

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