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Unformatted text preview: Review for Midterm 1 Lectures 1-9 MATTER
METALLIC metal atoms bendable, insoluble solids conducts MATTER SHELL MODEL Eight is Enough sharing or transfer Tension between kinetic energy of motion the potential energy of bonds and intermolecular attractions (Coulomb energy) IONIC metal plus nonmental brittle, soluble solids solutions conduct COVALENT nonmetals atoms gas, liquid, solid do not conduct Metals: loosely held electrons Liquids: attractive molecules Ideal gases: independent of molecular identity (PV=nRT) For similar mass, polar molecules have: - higher boiling points - higher solubility - greater smell For polymers, - straight chains = stiff - bent chains = stretchy - branched chains = flexible - H bonds = bullet-proof MOLECULES Clusters HONC 1234 EXTENDED 1D, 2D, and 3D HONC 1234 GASES Small molecules C1-C4 LIQUIDS Medium size C5-C12 SOLIDS Large molecules >C12 CHAINS 2 bonds stiff, stretchy, flexible LAYERS 3 bonds slippery NETWORK 4 bonds very hard Moles of Oxygen in a Breath Oxygen Solubility in Blood
Place in order of increasing gas solubility in water: H2 O2 Kr At STP, how many moles of oxygen are in one breath? A. 0.0020 moles B. 0.020 moles C. 0.20 moles D. 2.0 moles
How does oxygen dissolve in water?
Dipole induced dipole interactions are weak Only 8 mg oxygen per L of water at STP H O H!+ O !- H!+ O H !- O + ! H O H Oxygen in the Bloodstream
Cardiac output: 5 L blood per minute Oxygen needed: 250 mL per min 15 mL oxygen in plasma fraction (water) Nature uses intermolecular interactions to provide the necessary oxygen Oxygen Binding to Hemoglobin Hemoglobin is a protein (long chain of amino acids) that transports oxygen by reversible binding to an active site (heme) Why do you think the heme unit has 2 COOH groups? Fe2+ blue Fe2+ -- O2 red What is the shape of Fe2+ O2 ? Oxygen Binding to Hemoglobin Self Assembly
How would several copies of this molecule arrange in water? Intermolecular forces allow nature to carefully regulate what comes in and out of individual cells What causes the 3D structure of the hemoglobin protein? Why is the specific structure biologically important? Two histidine residues hang near the active site - One is bound to iron - The other is not (it's too far away) What's the role of the unbound histidine? More Self Assembly
Pick 2 of the following molecules and draw how they might interact. Repeat the process with several combinations. Which pairings have the strongest intermolecular forces? DNA Base Pairs Strong, selective hydrogen bonding enables unlimited copies of genetic material Molecular Representations What is the formula of the molecule shown below? Separation of Iodine How can you separate iodine, I2, from water? 1. Heat. The I2 will evaporate first. A. C5H9O B. C5H10O C. C5H11O O D. C5H12O E. C2H3O 2. Heat. The H2O will evaporate first. 3. Add hexane. The I2 will dissolve, but the H2O will not. 4. Add hexane. The H2O will dissolve, but the I2 will not. A. 1 B. 4 C. 2, 4 D. 1, 3 E. 2, 3 Miscibility of Liquids Nonmetal to Metal Transition
Use a shell model of the atom to explain why the conductivity increases down Group IVA +6 +14 +32 carbon, C silicon, Si germanium, Ge "Like dissolves like"
The effective nuclear charge, Zeff, decreases down Ozone, O3
Why does O3 exist as a bent structure?
-1 Graphite, Diamond, and Polyacetylene C (graphite) C (diamond) (CH2)n polyacetylene O O
+1 O O O O What is the bond order of O3? Why does cyclopropane, C3H6, exist but not triangular O3?
Which substances have moderate conductivity? A. 2 B. 1, 2 C. 2, 3 D. 1, 2, 3 E. 1, 3 Three Allotropes of Phosphorus P (red) Fiat Lux
"Let there by light." P (white) P (black) Which is the least stable? A. white B. red C. black ...
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