Inorganic Chemistry Notes (Lec. 03) 2021-2022 PDF

Inorganic Chemistry 1 Inorganic Chemistry Group 2021-2022  (Lec. 03) 2 Inorganic Chemistry Group 2022-2023  Electromagnetic Radiation (Nature of Light) Electromagnetic (EM) radiation is a form of energy that is all around us 3...

Inorganic Chemistry 1 Inorganic Chemistry Group 2021-2022  (Lec. 03) 2 Inorganic Chemistry Group 2022-2023  Electromagnetic Radiation (Nature of Light) Electromagnetic (EM) radiation is a form of energy that is all around us 3 Inorganic Chemistry Group 2021-2022 Wave-Like Properties (Characteristics of Light) 1. Wavelength (, lambda) 2. Frequency (, nu) 3. Wavenumber (ത) 4. Velocity (c) 5. Amplitude (A) 4 Inorganic Chemistry Group 2021-2022 Wavelength () The distance between two successive crests or two successive troughs Unit: Angstrom (Å) = 10-8 cm; nanometer (nm) = 10-7 cm. 5 Inorganic Chemistry Group 2021-2022 Frequency () Number of waves that pass point per unit time Unit: s-1 = Hertz (Hz) 6 Inorganic Chemistry Group 2021-2022 Amplitude (A) Distance between origin and crest or trough. 7 Inorganic Chemistry Group 2021-2022 Wave-Like Properties 8 Inorganic Chemistry Group 2021-2022 Wavenumber (ύ) Number of waves (cycles) per unit distance 1 ύ(Wave Number) =  Unit: cm-1 9 Inorganic Chemistry Group 2021-2022 Wave Velocity (C) Speed of Light (C) = 3x108 m/s 10 Inorganic Chemistry Group 2021-2022 Energy of light (EMR) 11 Inorganic Chemistry Group 2021-2022  Electromagnetic Spectrum The electromagnetic (EM) spectrum is the range of all types of EM radiation. 12 Inorganic Chemistry Group 2021-2022 Waves Interference Interference is a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude. 13 Inorganic Chemistry Group 2021-2022 Constructive Interference Constructive interference occurs whenever waves come together so that they are in phase with each other. Crests overlap with Crests (Troughs overlap with Troughs. 14 Inorganic Chemistry Group 2021-2022 Destructive Interference Destructive interference occurs when the maxima of two waves are 180 degrees out of phase: a positive displacement of one wave is cancelled exactly by a negative displacement of the other wave. The amplitude of the resulting wave is zero. Crests overlap with Troughs 15 Inorganic Chemistry Group 2021-2022 Absorption and Emission 16 Inorganic Chemistry Group 2021-2022 Absorption Vs Emission Spectrum 17 Inorganic Chemistry Group 2021-2022 Continuous Vs Line Spectrum Contain light of all wavelengths 18 Inorganic Chemistry Group 2021-2022 Absorption Line Spectrum 19 Inorganic Chemistry Group 2021-2022 Emission Line Spectrum 20 Inorganic Chemistry Group 2021-2022 Emission Line Spectrum Each element produces a unique set of spectral lines (Fingerprint). 21 Inorganic Chemistry Group 2021-2022 Hydrogen Emission Line Spectrum 22 Inorganic Chemistry Group 2021-2022 Hydrogen Line Emission Spectrum 23 Inorganic Chemistry Group 2021-2022 Explaining hydrogen's emission spectrum (Balmer 's equation) Balmer 's equation is used to calculate frequencies of spectral lines 𝟏 𝟏 𝟏 ύ= =𝐑 − ; 𝐧 = 𝟑, 𝟒, 𝟓 𝐚𝐧𝐝 𝟔  𝟐𝟐 𝐧𝟐 𝑹 Rydberg′s 𝑪𝒐𝒏𝒔𝒕𝒂𝒏𝒕 = 𝟏. 𝟎𝟗𝟕𝒙𝟏𝟎𝟕 𝒎−𝟏 = 𝟏. 𝟎𝟗𝟕𝒙𝟏𝟎𝟓 𝒄𝒎−𝟏 = 𝟏. 𝟎𝟗𝟕𝒙𝟏𝟎−𝟐 𝒏𝒎−𝟏 24 Inorganic Chemistry Group 2021-2022 Balmer's equation 𝒆. 𝒈: 𝒏 = 𝟔 𝟏 𝟏 𝟏 =𝑹( 𝟐 − 𝟐)  𝟐 𝒏 𝟏 𝟏 𝟏 = 𝟏. 𝟎𝟗𝟕𝒙𝟏𝟎−𝟐 − = 𝟐. 𝟒𝟑𝟕𝟕𝒙𝟏𝟎−𝟑 𝒏𝒎−𝟏  𝟐𝟐 𝟔𝟐 𝟏 = = 𝟒𝟏𝟎. 𝟏 𝒏𝒎 Violet lines 𝟐.𝟒𝟑𝟕𝟕𝒙𝟏𝟎−𝟑 25 Inorganic Chemistry Group 2021-2022 Balmer's equation 𝒆. 𝒈: 𝒏 = 𝟓 𝟏 𝟏 𝟏 =𝑹( 𝟐 − 𝟐)  𝟐 𝒏 𝟏 𝟏 𝟏 = 𝟏. 𝟎𝟗𝟕𝒙𝟏𝟎−𝟐 − = 𝟐. 𝟑𝟎𝟑𝟕𝒙𝟏𝟎−𝟑 𝒏𝒎−𝟏  𝟐𝟐 𝟓𝟐 𝟏 = = 𝟒𝟑𝟒. 𝟎𝟖 𝒏𝒎 Blue Violet lines 𝟐.𝟒𝟑𝟕𝟕𝒙𝟏𝟎−𝟑 26 Inorganic Chemistry Group 2021-2022 Balmer's equation 𝒆. 𝒈: 𝒏 = 𝟒 𝟏 𝟏 𝟏 =𝑹( 𝟐 − 𝟐)  𝟐 𝒏 𝟏 𝟏 𝟏 = 𝟏. 𝟎𝟗𝟕𝒙𝟏𝟎−𝟐 − = 𝟐. 𝟎𝟓𝟔𝟖𝒙𝟏𝟎−𝟑 𝒏𝒎−𝟏  𝟐𝟐 𝟒𝟐 𝟏 = = 𝟒𝟖𝟔. 𝟏𝟗 𝒏𝒎 Blue Green lines 𝟐.𝟒𝟑𝟕𝟕𝒙𝟏𝟎−𝟑 27 Inorganic Chemistry Group 2021-2022 Balmer's equation 𝒆. 𝒈: 𝒏 = 𝟑 𝟏 𝟏 𝟏 =𝑹( 𝟐 − 𝟐)  𝟐 𝒏 𝟏 𝟏 𝟏 = 𝟏. 𝟎𝟗𝟕𝒙𝟏𝟎−𝟐 − = 𝟏. 𝟓𝟐𝟑𝟔𝒙𝟏𝟎−𝟑 𝒏𝒎−𝟏  𝟐𝟐 𝟑𝟐 𝟏 = = 𝟔𝟓𝟔. 𝟑𝟒 𝒏𝒎 Red lines 𝟐.𝟒𝟑𝟕𝟕𝒙𝟏𝟎−𝟑 28 Inorganic Chemistry Group 2021-2022 Complete hydrogen's emission spectrum 29 Inorganic Chemistry Group 2021-2022 Balmer-Rydberg's equation 𝟏 𝟏 𝟏 ύ= =𝑹 ( 𝟐 − )  𝒏𝒊 𝟐 𝒏𝒇 Or 𝟏 𝟏 𝟏 ύ= =𝑹 ( 𝟐 − ) ;m>n  𝒏 𝒎 𝟐 30 Inorganic Chemistry Group 2021-2022  (Lec. 04) 31 Inorganic Chemistry Group 2021-2022 Bohr’s Atomic Model 32 Inorganic Chemistry Group 2021-2022 Bohr’s Atomic Model 1.The electron in a hydrogen atom moves around the nucleus in a circular path like planets around a sun without radiating energy. 33 Inorganic Chemistry Group 2021-2022 Bohr’s Atomic Model 2. electrons can only exist in certain orbits and thus, can only have certain energies. As a result, we say that the energies of the electrons are quantized and the energy of electron in a specific is given by: 𝒉𝒄 R (Rydberg constant) = 1.097×107 m−1 𝑬𝒏 = −𝑹 𝟐 h (Planc Constant)= 6.63×10−34 J · s 𝒏 C (velocity of light ) = 3.00×108 m/s n is the number of the orbit you are Stability interested in. n can have any integer value (no decimals!) from 1 to infinity, n = 1, 2, 3, 4 … ∞. 34 Inorganic Chemistry Group 2021-2022 The Quantization of Energy 35 Inorganic Chemistry Group 2021-2022 The Quantization of Energy Planck’s Law Max Planck explained that the energy of electromagnetic waves is quantized rather than continuous. h = Planck’s constant 𝑬=𝒉𝝂 = 6.63 x 10-34 J.s (Kg.m2/s) Planck assumed that the energy of blackbody radiation was in the form 𝑬 = 𝒏𝒉 𝝂 n = 1, 2, 3 (integers) 36 Inorganic Chemistry Group 2021-2022 Energy Level Diagram For H - atom 37 Inorganic Chemistry Group 2021-2022 Bohr’s Atomic Model 3. The electron can only lose energy by making a transition from high energy level to another low energy level. 38 Inorganic Chemistry Group 2021-2022 Bohr’s Atomic Model 39 Inorganic Chemistry Group 2021-2022 Bohr’s Atomic Model ∆E= 𝑬𝟐 − 𝑬𝟏 𝟏 𝟏 ∆E = (−𝑹𝒉𝒄 𝟐 ) − −𝑹𝒉𝒄 𝟐 𝒏𝟐 𝒏𝟏 𝟏 𝟏 ∆E = 𝑹𝒉𝒄( 𝟐 − 𝟐) 𝒏𝟏 𝒏𝟐 or 𝟏 𝟏 ∆E = 𝑹𝒉𝒄( 𝟐 − 𝟐) ;𝒎 > 𝒏 𝒏 𝒎 40 Inorganic Chemistry Group 2021-2022 Limitations of (Drawbacks) of Bohr’s Model of an Atom 1. Unable to explain instance of additional quantum numbers. 2. Unable to explain dual nature of electron and Heisenberg Uncertainty Principle. 3. Unable to explain how to determine the spectra of multi electron atoms. 41 Inorganic Chemistry Group 2021-2022 The Photoelectric Effect In 1888, Heinrich Hertz discovered that when light strikes the surface of certain metals, electrons are ejected. This phenomenon is Heinrich Rudolf Hertz called the photoelectric effect. 42 Inorganic Chemistry Group 2021-2022 The Photoelectric Effect 43 Inorganic Chemistry Group 2021-2022 The Photoelectric Experiment 44 Inorganic Chemistry Group 2021-2022 Reason of Photoelectric Effect This effect can be attributed to the transfer of energy from the light to an electron. 45 Inorganic Chemistry Group 2021-2022 Threshold frequency (νo) < 0 = 0 > 0 46 Inorganic Chemistry Group 2021-2022 Threshold frequency (νo) Minimum value of frequency below which photoelectric emission is not possible however high the intensity of incident light may be. (νo) depends on the nature of the metal emitting photoelectrons. 47 Inorganic Chemistry Group 2021-2022 Einstein’s Photoelectric Equation Photon Electron E = hν E =1/2 mv2 Metal Surface Work Function () = hν0 1 hν = hν0 + mv 2 2 K.E = ½ mv2= hν – hν0 K.E = h(ν - νo) 48 Inorganic Chemistry Group 2021-2022 Kinetic Energy of Ejected Electrons Kinetic Energy of ejected Electrons depends on frequency of incident light and not its intensity (number of incident photons). 49 Inorganic Chemistry Group 2021-2022 Work function and ionization energy The Work function () hνo Minimum amount of energy necessary to remove a free electron from the surface of the metal. M(s) +E → M+(s) + e− Ionization energy (I.E) amount of energy required to remove an electron from an atom in the gaseous state M(g) + E →M +(g) + e− 50 Inorganic Chemistry Group 2021-2022 Work function and ionization energy of some metals Element Work function () (eV) Ionization Energy (eV) Copper (Cu) 4.7 7.7 Silver (Ag) 4.72 7.57 Aluminum (Al) 4.20 5.98 Gold (Au) 5.17 9.22 Boron (B) 4.45 8.298 Beryllium (Be) 4.98 9.32 Bismuth (Bi) 4.34 7.29 Cesium (Ce) 1.95 3.89 Iron (Fe) 4.67 7.87 Sodium (Na) 2.36 5.13 Lithium (Li) 2.93 5.39 Potassium (K) 2.3 4.34 51 Inorganic Chemistry Group 2021-2022 Light Intensity and number ejected electrons Light Intensity  number emitted electrons with the same kinetic energy. 52 Inorganic Chemistry Group 2021-2022 Photoelectric Effect Conclusion Photon is a “particle” of light Light has both: wave nature & particle nature 53 Inorganic Chemistry Group 2021-2022 Dual Nature of Light (Wave- Particle Duality) Light has a dual nature: 1. Sometimes it behaves like a particle (called a photon), which explains how light travels in straight lines. 2. Sometimes it behaves like a wave, which explains how light bends (or diffracts) around an object. 54 Inorganic Chemistry Group 2021-2022 Dual Nature of Light Wave E = h = hc/λ Planck's law Light Particle E = mc2 Einstein's law 55 Inorganic Chemistry Group 2021-2022 Dual Nature of Electron French scientist Louis de Broglie suggested that the particles like electrons, protons, neutrons, etc have also dual nature. i.e. they also can have particle as well as wave nature. De Broglie pointed out the electron orbits in Bohr’s model were similar to the behavior of waves. 56 Inorganic Chemistry Group 2021-2022 Dual Nature of Electron 57 Inorganic Chemistry Group 2021-2022 de Broglie wave A moving particle can be associated with a wave, known as de Broglie wave or matter waves. 58 Inorganic Chemistry Group 2021-2022  de Broglie wavelength Momentum= the E= mc2 quantity of movement 𝑪 h = p*c E = m*c* c E = p*c  h h h p=   =  = p mv Planck's constant de Broglie wavelength Mass Velocity 59 Inorganic Chemistry Group 2021-2022 Conclusions i) de Broglie wavelength is inversely proportional to the velocity of the particle. If the particle moves faster, then the wavelength will be smaller and vice versa. 𝟏  v 60 Inorganic Chemistry Group 2021-2022 Conclusions ii) If the particle is at rest (v = 0), then the de Broglie wavelength is infinite. Such a wave can not be visualized. h  = mv If v = 0  =∞ 61 Inorganic Chemistry Group 2021-2022 Conclusions iii) de Broglie wavelength is independent of the charge of the particle. h  = mv 62 Inorganic Chemistry Group 2021-2022 Conclusions iv) de Broglie wavelength is inversely proportional to the mass of the particle. The wavelength associated with a heavier particle is smaller than that with a lighter particle. 𝟏  m 63 Inorganic Chemistry Group 2021-2022 Heisenberg Uncertainty Principle 64 Inorganic Chemistry Group 2021-2022 Heisenberg Uncertainty Principle The position and the velocity of an object cannot both be measured exactly, at the same time ? ? Position Momentum Position Momentum (velocity) (velocity) 65 Inorganic Chemistry Group 2021-2022 Heisenberg Uncertainty Principle 66 Inorganic Chemistry Group 2021-2022 Heisenberg Uncertainty Principle ħ ∆𝐏. ∆𝐗  𝐡  ;ħ= 𝐡 𝟒𝛑 𝟐 𝟐𝛑 ∆𝐏 uncertainty in the momentum (m∆V). ∆𝐗 uncertainty in position. m mass. V velocity. h Planck’s constant. 67 Inorganic Chemistry Group 2021-2022 ‫‪Heisenberg Uncertainty Principle‬‬ ‫هذا المبدأ يخبرنا بأننا غير قادرين على معرفة كل شيء بدقة‪ ،‬وال‬ ‫يمكننا قياس كل شيء بدقة‪ ،‬وإنما هناك قدر معين ال نعرفه‪ ،‬وال‬ ‫نستطيع قياسه‬ ‫‪68‬‬ ‫‪Inorganic Chemistry Group‬‬ ‫‪2021-2022‬‬ Why Heisenberg's uncertainty principle is important? It is impossible to determine the location and velocity of an electron at any given moment around the atom, and if you can measure the velocity with a certain accuracy, then - at the same moment - you will not be able to determine the position of the electron. Electrons in an atom don't travel in precise orbits, and their motion is random and hard to predict. 69 Inorganic Chemistry Group 2021-2022