CHAPTER 8 FULL NOTES - CHEM 1A03: Intro. Chemistry I What...

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Department of Department of 1 Chemistry CHEM 1A03: Intro. Chemistry I Essential Elements: Chemistry, Life & Health Ch.8: Electrons in Atoms What do we understand about atoms? • Mostly space •Nuc leus • Electrons – Described by quantum mechanics, not traditional mechanics – Behave like particles and waves – Their movement has energy changes – Not at fixed distances/in fixed locations – Orbitals describe where they probably are – Quantum numbers describe orbitals Department of Department of 2 Chemistry © Department of 3 Chemistry Electromagnetic Spectrum (Fig. 8-3) c= νλ E ∝ν E 1/ λ © Department of Department of 4 Chemistry i-Clicker Question #1 Choose the TRUE statement: A. The wavelength of blue light is shorter than that of orange light. B. The frequency of red light is smaller than that of violet light. C. The energy of yellow light is smaller than that of blue light. D. All statements are true. © Department of 5 Chemistry Atomic spectra Discontinuous (Line) spectra of atoms ; few λ • Atomic spectrum of H H 2 He Li salt Na salt K salt © Department of Department of 6 Chemistry Sun’s Emission Spectrum Sun (T = 6,000K) ©
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Department of Department of 7 Chemistry Earth’s Protective Shield: Ozone A. Ozone & UV Exposure 90% UVB radiation (280-320 nm) from the sun is selectively absorbed by photolysis of O 3 in stratosphere, with peak at ~ 20km from Earth’s surface Lower O 3 levels increase the transmittance of UV B radiation to earth Æ Montreal Protocol: 1987 From Sun To Earth Surface O 3 (g) O 2 (g) + O (g) Altitude (km) + Heat h ν = 280 – 320 nm Mt. Everest 8.8 km © Department of Department of 8 Chemistry Ozone Depletion & UV Exposure B. Biological Impacts • UV B radiation can ionize biological molecules (DNA, Protein) Chronic exposure to UVB rays increases chance of skin cancer, cataracts & genetic mutations • Body’s response: produce melanin (dark pigment) to filter UV B radiation. O O - NH3 + HN Tryptophan (Trp) Aromatic Amino Acid in Protein N N N N NH 2 O OH OH HO Adenosine (A) Aromatic Base in RNA/DNA or H © Department of 9 Chemistry UV Exposure & Sunscreen C. Chemistry of Sunscreen • Propose alternative ways to decrease exposure to UV radiation? • Use of sunscreen/cosmetics containing UV absorbing chemicals UV B UV A 2 Major Chemical Sunscreens: Broad spectrum coverage λ O OH OMe oxybenzone CH 3 O O O 2-ethylhexyl p-methoxycinnamate © Department of Department of 10 Chemistry Quantum Numbers & Orbitals Section 8.6 [not part of the course] introduces: • Schrödinger equation: combines ideas of particle & wave behaviour to describe energy of e in atom • We’ll use the results of 8.6 - Orbitals – Orbitals are wavefunctions, ψ , solutions to the Schrödinger equation – Orbitals are described by 3 quantum numbers – Orbitals describe regions of high probability of finding an electron (high charge density) © Department of 11 11 Chemistry Review: Quantum Numbers, Orbitals, Electron Configurations • The following slides ( 12-19
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This note was uploaded on 12/03/2010 for the course CHEM 1a03 taught by Professor Landry during the Fall '08 term at McMaster University.

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CHAPTER 8 FULL NOTES - CHEM 1A03: Intro. Chemistry I What...

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