01 02 Lecture 01 19 2018 - UC Santa Barbara
1/19/18 CHEM 109A Organic Chemistry Wait Lists and Add code requests: Got you emails, working on it! Questions? (non chemistry) Chika Anyiwo, undergraduate advisor anyiwo@chem.ucsb.edu 2017 Pearson Education, Inc. CHEM 109A Organic Chemistry Questions? (chemistry!) CLAS tutor for this 109A course Timothy Ngo: txngo@umail.ucsb.edu Sign up! 2017 Pearson Education, Inc. 1
1/19/18 CHEM 109A Organic Chemistry https://labs.chem.ucsb.edu/zakarian/armen/ courses.html Chapter 1 Electronic Structure and bonding 2017 Pearson Education, Inc. Ch. 1: Important topics/concepts Covalent Bonds: polar, or nonpolar (electronegativity) compare polarity of bonds, such as H-C vs H-N vs H-O vs H-F Structures: Lewis structures (Kekule, condensed, skeletal) properly placing lone pairs of e, formal charges H H O BF3 H condensed F O B F H ? F skeletal Lone pairs? Formal charges? Lewis Bonds: σ and π bonds (single bonds, double bonds, triple bonds) σ formed by orbital overlap, s s, s p, p s, or hybridized π formed by overlap between p orbitals double bond 1 σ bond 1 π bond triple bond 1 σ bond 2 π bonds 2017 Pearson Education, Inc. 2
1/19/18 Ch. 1: Important topics/concepts Hybrid orbitals: s and p orbitals mix to form new hybrid orbitals (comes from valence-shell electron-pair repulsion (VSEPR) theory explains geometry of CH4 and many other molecules Geometry (shape of molecules): CH4: tetrahedral, four sp3 orbitals, bond angle 109o, H2C CH2, ethylene, three sp2 orbitals, one p orbital, bond angle 120o HC CH, acetylene, two sp bonds, 2 p orbitals, bond angle 180o Bond length and strength: shorter bonds are stronger. ETHYLENE ACETYLENE 2017 Pearson Education, Inc. The Distribution of Electrons in an Atom quantum numbers n l ml 2 e per orbital The first shell is closest to the nucleus. The closer the atomic orbital is to the nucleus, the lower its energy. Within a shell, s lower in energy than p. 2017 Pearson Education, Inc. 3
1/19/18 The Distribution of Electrons in an Atom quantum numbers n l ml 2 e per orbital The first shell is closest to the nucleus. The closer the atomic orbital is to the nucleus, the lower its energy. Within a shell, s lower in energy than p. y z x 2s orbital, presents only one phase for overlap 2017 Pearson Education, Inc. lobes with opposite phases Achieving a Filled Outer Shell by Sharing Electrons 2017 Pearson Education, Inc. 4
1/19/18 How Many Bonds Does an Atom Form? 2017 Pearson Education, Inc. Nonpolar and Polar Covalent Bonds Nonpolar covalent bond bonded atoms are the same or have similar electronegativities. Polar covalent bond bonded atoms have different electronegativities. 2017 Pearson Education, Inc. 5
1/19/18 Nonpolar and Polar Covalent Bonds Nonpolar covalent bond bonded atoms are the same or have similar electronegativities. Polar covalent bond bonded atoms have different electronegativities. 2017 Pearson Education, Inc. Nonpolar and Polar Covalent Bonds Nonpolar covalent bond bonded atoms are the same or have similar electronegativities. Polar covalent bond bonded atoms have different electronegativities. 2017 Pearson Education, Inc. 6
1/19/18 ELECTRONEGATIVITY OF ELEMENTS Differences in electronegativity between atoms lead to polar bonds The bigger the difference, the more polar the bond 2017 Pearson Education, Inc. The Greater the Difference in Electronegativity, the More Polar the Bond Nonpolar covalent bond: electonegativity difference 0.5 Polar covalent bond: electonegativity difference 0.5 – 1.9 Electronegativity difference 1.9: electrons are not shared; atoms are held together by the attraction of opposite charges 2017 Pearson Education, Inc. 7
1/19/18 Dipole Moment Dipole moment size of the charge x the distance between the charges The greater the difference in electronegativity, the greater the dipole moment and the more polar the bond. 2017 Pearson Education, Inc. Dipole Moment Dipole moment size of the charge x the distance between the charges The greater the difference in electronegativity, the greater the dipole moment and the more polar the bond. 2017 Pearson Education, Inc. 8
1/19/18 Electrostatic Potential Maps 2017 Pearson Education, Inc. Lewis Structures Important items: H lone pairs, H O BF3 H condensed F O B F H formal charges ? F skeletal Lewis 2017 Pearson Education, Inc. 9
1/19/18 Carbon Forms Four Bonds C If carbon does not form four bonds, it has a charge (or it is a radical). 2017 Pearson Education, Inc. Nitrogen Forms Three Bonds N Nitrogen has one lone pair. If nitrogen does not form three bonds, it is charged. 2017 Pearson Education, Inc. 10
1/19/18 Oxygen Forms Two Bonds O Oxygen has two lone pairs. If oxygen does not form two bonds, it is charged. 2017 Pearson Education, Inc. Hydrogen and the Halogens Form One Bond Cl H A halogen has three lone pairs. If hydrogen or halogen does not form one bond, it has a charge (or it is a radical). 2017 Pearson Education, Inc. 11
1/19/18 The Number of Bonds Plus the Number of Lone Pairs Equals Four 2017 Pearson Education, Inc. Lewis Structures 2017 Pearson Education, Inc. 12
1/19/18 Formal Charge Important items: lone pairs, formal charges Formal Charge the # of valence electrons – (the # of lone-pair electrons the # of bonds) H H O BF3 H H condensed F O B F ? F skeletal Lewis 2017 Pearson Education, Inc. How to Draw a Lewis Structure review Gen. Chem. and practice! Homework: problems 49, 54, 55 NO3– (anion of nitric acid HNO3) Determine the total number of valence electrons (5 6 6 6 23). Because they are negatively charged, add another electron 24. Avoid O—O bonds. Check for formal charges. 2017 Pearson Education, Inc. 13
1/19/18 Kekulé Structures and Condensed Structures 2017 Pearson Education, Inc. Kekulé Structures and Condensed Structures 2017 Pearson Education, Inc. 14
1/19/18 Kekulé Structures and Condensed Structures 2017 Pearson Education, Inc. Skeletal Structures Skeletal structures show the carbon-carbon bonds as lines, but do not show the carbons or the hydrogens that are bonded to the carbons. 2017 Pearson Education, Inc. 15
1/19/18 Back to Bonding: Forming a Sigma Bond 2017 Pearson Education, Inc. Waves Can Reinforce Each Other Waves Can Cancel Each Other 2017 Pearson Education, Inc. 16
1/19/18 Atomic Orbitals Combine to Form Molecular Orbitals Orbitals are Conserved # of Molecular Orbitals # of Atomic Orbitals Combined 2017 Pearson Education, Inc. Side-to-Side Overlap of In-Phase p Orbitals Forms a π Bond 2017 Pearson Education, Inc. 17
Ch. 1: Important topics/concepts Structures: Lewis structures (Kekule, condensed, skeletal) properly placing lone pairs of e, formal charges Bonds: σ and π bonds (single bonds, double bonds, triple bonds) σ formed by orbital overlap, s s, s p, p s, or hybridized π formed by overlap between p orbitals double bond 1 σ bond 1 π bond
Introduction of Chemical Reaction Engineering Introduction about Chemical Engineering 0:31:15 0:31:09. Lecture 14 Lecture 15 Lecture 16 Lecture 17 Lecture 18 Lecture 19 Lecture 20 Lecture 21 Lecture 22 Lecture 23 Lecture 24 Lecture 25 Lecture 26 Lecture 27 Lecture 28 Lecture
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Partial Di erential Equations MSO-203-B T. Muthukumar tmk@iitk.ac.in November 14, 2019 T. Muthukumar tmk@iitk.ac.in Partial Di erential EquationsMSO-203-B November 14, 2019 1/193 1 First Week Lecture One Lecture Two Lecture Three Lecture Four 2 Second Week Lecture Five Lecture Six 3 Third Week Lecture Seven Lecture Eight 4 Fourth Week Lecture .
Introduction to Quantum Field Theory for Mathematicians Lecture notes for Math 273, Stanford, Fall 2018 Sourav Chatterjee (Based on a forthcoming textbook by Michel Talagrand) Contents Lecture 1. Introduction 1 Lecture 2. The postulates of quantum mechanics 5 Lecture 3. Position and momentum operators 9 Lecture 4. Time evolution 13 Lecture 5. Many particle states 19 Lecture 6. Bosonic Fock .
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