Chem 161-2011 Lecture 4, Chapter 3

Chem 161-2011 Lecture 4, Chapter 3 - CHEMISTRY 161-2011...

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Chem 161-2011 Lecture 4, Chapter 3 1 CHEMISTRY 161-2011 LECTURES 4 CHAPTER 3 QUANTUM THEORY AND THE ELECTRONIC STRUCTURE OF ATOMS ANNOUNCEMENTS E-MAIL ATTENDANCE EXAMS
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Chem 161-2011 Lecture 4, Chapter 3 2 PLAN FOR TODAY : Finish chapter 2 Chapter 3: Energy and energy changes Forms of energy Thermal energy Potential energy Chemical energy Electrostatic energy Law of conservation of energy The nature of light Electromagnetic spectrum Properties of waves Wavelength Frequency Amplitude Quantum theory Quantization of energy Blackbody radiation Q u a n t u m Planck’s constant Quantum theory Photons and the photoelectric effect Threshold frequency Bohr’s theory of the hydrogen atom Atomic line spectra Line spectrum of hydrogen Ground state Excited state Wave properties of matter de Broglie hypothesis Diffraction of electrons
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Chem 161-2011 Lecture 4, Chapter 3 3 Mole – Avogadro’s number MOLES Note to ET: Define moles MOLE
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Chem 161-2011 Lecture 4, Chapter 3 4 ORIGIN OF “MOLES” Chemists found that (as an example): Hydrogen + Oxygen Water 2 g 1 6 g 1 8 g As time went on it was determined that these quantities were equivalent to: 2 H + O H 2 O 12.04 x 10 23 atoms 6.022 x 10 23 atoms 6.022 x 10 23 molecules = 2:1 ratio of H atoms to O atoms 1H 2 O Chemists frequently work with atoms and molecules. Mass is only used to calculate the number of atoms and molecules. Although quantities such as 2.0g, 16.0g or 18.0g are convenient to work with, the corresponding number of atoms and molecules (12.04 x 10 23 atoms, 6.02 x 10 23 atoms or 6.02 x 10 23 molecules) is not convenient. Inconvenient Convenient 12 eggs 1 dozen eggs (or 1 doz anything) 144 buttons 1 gross of buttons (or 1 gr anything) 500 sheets of paper 1 ream of paper 6.022 x 10 23 atoms* 1 mole of atoms (or 1 mole anything) 1 . 6 6 x 1 0 -24 g 1 atomic mass unit * This is the number of atoms in 12g of 12 C and the number of atoms in 1g of hydrogen (pure H-1 isotope); 12 C was arbitrarily picked as the reference. Now we have convenient numbers for atoms/molecules and convenient numbers for masses: Hydrogen + Oxygen Water 2.0g 16.0g 18.0g (12.044x10 23 atom) (6.022x10 23 atom) (6.022x10 23 molecules) 2 mol of atoms 1 mol of atoms 1 mol of molecules
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Chem 161-2011 Lecture 4, Chapter 3 5 ET note: Not everything goes through moles, e.g., volume to grams, grams to volume, atoms to molecules, molecules to atoms. ZUMDAHL 6 TH EDITION CHEM 161-2007 RECITATION 4th WEEK CHAPTER 5 - STOICHIOMETRY moles A moles B atoms molecules (or atoms if particle is an a t o m ) M B or V B g B or MW B V B M A or V A V A g A or MW A MOLES ARE AT THE CENTER (FOR CONVERSIONS, WORK THROUGH MOLES) MW (D = g/V) mol A = M A L A moles = PV/RT for gases (molecules x atoms/molecule = atoms) (moles A = g A /MW A ) mol B = M B L B (moles B = g B /MW B ) (D = g/V) (moles x Avog. No. = molecules (or atoms)) %A % B Empirical formula Molecular formula (MW/EW) x Emp form = molec form moles = g/MW PV = nRT moles = M x V P 1 V 1 /n 1 T 1 =P 2 V 2 /n 2 T 2 g/MW = M x V 6.022x10 23 molecule/mole D = g/L MW A or AW A = g A /mole A moles A = g A /MW A
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Chem 161-2011 Lecture 4, Chapter 3 6 PERIODIC TABLE (frequently used for calculation of molar masses) 1A 2A 3B 4B
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This note was uploaded on 02/20/2012 for the course 160 161 taught by Professor Kim during the Fall '08 term at Rutgers.

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Chem 161-2011 Lecture 4, Chapter 3 - CHEMISTRY 161-2011...

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