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A. Electronegativity - The ability of an atom to attract electrons to itself in a bond 1.Periodic Trends (link to size) Metals – Low Electronegativity Non- Metals – High Electroneg The smaller the atom, the higher the electronegativity Types of Bonds
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a.Molecular Compounds (non-metals) Sharing of electrons Covalent or polar covalent bonds Ex: H 2 b. Ionic Compounds (metal + non-metal) Exchange (stealing) of electrons Ex: NaCl Types of Bonds
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3. Types of bonds Electronegatvity Difference Example:Na-F Types of Bonds
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Are the following bonds ionic, polar covalent or covalent? Ba – BrC – N Be – FB – H O – HBe – Cl P – HC – H O – O Types of Bonds
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Ionic – Electron is completely removed from one atom and goes to another a. Metal – Low e-neg (loses e-) b. Non-metal – high e-neg (gains e-) Ionic
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IAIIAIIIAIVAVAVIAVIIA Hydride H - Lithium Li + Beryllium Be 2+ Carbide C 4- Nitride N 3- Oxide O 2- Fluoride F - Sodium Na + Magnesium Mg 2+ Aluminum Al 3+ Phosphide P 3- Sulfide S 2- Chloride Cl - Potassium K + Calcium Ca 2+ Selenide Se 2- Bromide Br - Rubidium Rb + Strontium Sr 2+ Telluride Te 2- Iodide I - Cesium Cs + Barium Ba 2+ Common Charges
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Complete the following chart: FormulaLewis Dot K and I Sr and F Ba and Cl Sr and N Ba and O
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Complete the following chart: FormulaLewis Dot K and S Al and O Na and Br Ca and O
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1.Not Separate molecules 2.Crystal Lattice – Regular 3D pattern in an ionic solid Ionic Solids
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at lattice pointsions at lattice points
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1.Water (molecule) dissolves salt (ionic crystal): Ions in Water
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Molecules
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Many ionic compounds are called salts CaCl 2 Calcium Chloride (Quik-Joe) NaHCO 3 Sodium bicarbonate(Baking soda) NaF Sodium Fluoride (toothpaste) CaCO 3 Calcium Carbonate(Chalk, antacid) NaOH Sodium Hydroxide (Drano) MgSO 4 Magnesium Sulfate(Epsom Salts) All big clumps (crystals) of Ions Other Salts
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Group of atoms held together by covalent and polar covalent bonds (SHARING) Usually composed of non-metals Stronger than Ionic bonds Separate (discrete) groups of atoms What is a Molecule?
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A. Single Bonds (LD and Stick) CH 4 H2OH2O (bonded versus lone pairs) Old School Lewis Dots
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The Lone Pear(Pair) rides again!
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N and H P and F Cl and O NH 2 CH 3 Old School Lewis Dots
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You try: As and H N and Br CH 3 CH 2 OH NH 2 CH 2 SiCl 3 CH 3 OCH 3 Old School Lewis Dots
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As and Cl C and Br CH 3 CH 2 NH 2 CH 3 OCH 2 CH 3
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B. Multiple Bonds CO 2 C 2 H 2 Old School Lewis Dots
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You Try: HCN N 2 Al N O 2 Old School Lewis Dots
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Rules 1. Sum all valence electrons, including charges 2. Single Bonds 3. Outer atoms get an octet except H 4. Center gets rest even if it violates the octet 5. Double/triple bonds if center atom still does not have an octet Lewis Dots
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NH 3 NCl 3 SF 6 Br 2 O ClF 5 Lewis Dots
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You try: SF 4 KrF 4 Cl 2 O ClF 3 H 2 SO 4
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Warm-Up: CH 3 CH 2 NH 2 SeF 4 KrCl 4 H 2 O 2 BaCl 2 (this is an ionic cmpd)
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CO 2 HCN CN - ICl 4 - NO + Lewis Dots
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CO 3 2- H 3 O + NH 4 + PO 4 3- SO 2
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Hydrogenonly makes one bond Gr I, II and III Especially if with a halogen BeCl 2 BCl 3 AlCl 3 Less Than an Octet
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Non-Metals starting with P More Than an Octet PSClAr AsSeBrKr TeIXe
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PCl 5
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Warm-Up:O 3 Definition – When a molecule can exist in more than one arrangement of electrons 1. Atoms don’t move 2. Only the electrons (double bonds) move 3. Also called “delocalized bonding” Resonance Structures
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Si 2 H 4 AsO 4 3- CS 3 2- H 3 S + PH 4 +
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SPECIAL NOTE: Oxygen rarely makes three bonds for resonance structures. Those structures are not common. Resonance Structures
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PO 3 - HSO 3 +
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Examples 1. NO 2 -, CO 3 2-, CHO 2 -, HNO 3 2. Which needs resonance, SO 3 or SO 3 2- Resonance Structures
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Valence Shell Electron Pair Repulsion Theory (VSEPR) VSEPR – Valence electron pairs on the central atom push as far apart as possible. Shapes of Molecules
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1. Linear (180 o ) BeH 2 CO 2 Shapes of Molecules
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2. Trigonal Planar (120 o ) NO 3 - Shapes of Molecules
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3. Tetrahedral (109.5 o ) CH 4 Shapes of Molecules
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4. Trigonal Pyramidal (~107 o ) NH 3 Shapes of Molecules
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5. Bent (Type I, ~104.5 o ) H 2 O Shapes of Molecules
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O HH
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Bent (Type II, 120 o ) SO 2
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Atoms are bent Bond angle = 120 o
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6. Trigonal Bipyramid (120 o, 90 o ) PCl 5 Shapes of Molecules
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7. Octahedral (90 o ) SF 6 Shapes of Molecules
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DRAW LEWIS DOT STRUCTURES AND PREDICT THE BOND ANGLES FOR: PH 3 GeO 2 PCl 5 NCl 3 H 2 SSiH 4 CF 4 SO 3 2- SeCl 6 SO 3
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Ex: All single bonds: PH 3 H 2 SSiH 4 SeCl 6 AsF 5 BeCl 2 CH 3 FHFBF 3 Shapes of Molecules
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Ex: Multiple Bonds: N 2 HCN CO 2 H 2 CO Shapes of Molecules
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SO 2 2+ SO 2 2- SO 2 SO 3 SF 6
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Shapes of Molecules
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1. Examples: BeH 2 H2OH2O BH 3 NH 3 2. There is no relationship between formula and shape Shapes and Formula?
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PO 2 - PO 3 - PO 3 3- PO 4 3- XeF 4
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Household Molecules H 2 O HCl NH 3 H 2 SO 4
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1. Polar molecule – Overall, the electrons are attracted more to one end of an entire molecule 2. Non-Polar Molecule – The electrons are spread out evenly over the entire molecule -/ + Partial (not full) charges Polar Molecules
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H 2 H 2 O CH 4 H 2 CO (C is the center)
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H 2 H 2 O CH 4 H 2 CO
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BeCl 2 NH 3 CO 2 CSO HCN (triple bond)
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CCl 4 CH 3 Cl CH 2 Cl 2 CHCl 3 HBeCl HBr
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CH 3 ClCH 2 Cl 2 CHCl 3 HBeClHBr Polar Molecules
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Lewis DotShapePolar or Non- polar molecule? H2OH2O NH 3 CH 3 Cl CH 3 CH 2 OH SO 2
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Hydrogen Bonding a. Water Beading b. SurfaceTension c. Ice d. DNA e. Miscibility (NH 3, ethanol) f. Immiscibility (Water and Oil)
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Water Beading
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Surface Tension
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Ice
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Molecules Boiling Point Generally increases with increasing molar mass H 2 O unusually high - H-bonding
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DNA
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DNA is TWO molecules that are hydrogen bonded (like a zipper)
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DNA Human Genome Project
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DNA in one cell = 1 meter DNA in all your cells = 93,000,000 miles
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Miscibility “Like dissolves like.” Polar dissolves Polar Water, ammonia
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Miscibility
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Water, alcohol
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Miscibility Water, alcohol
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Miscibility Non-Polar dissolves Non-Polar oil paint, thinner
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Miscibility
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Would acetone (shown below) dissolve in water? Acetone :O: || CH 3 CCH 3
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Molecules London Dispersion Forces Very weak force Caused by temporary imbalances in electrons
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Molecules London Forces: Inorganic Molecules More electrons, more chance for temporary dipole Boiling Point Table HalogenMolar Mass BP( o C)Noble Gas Atomic Mass BP( o C) F 2 (g)38.0-188He4.0-268 Cl 2 (g)71.0-35Ne20.2-246 Br 2 (l)159.859Ar39.9-186 I 2 (s)253.8185Kr83.8-152
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Consider the following molecules: Te 2 S 2 O 2 Se 2 a.Rank them from weakest to strongest London forces b.Which should have the highest boiling point? Which should have the lowest? c.Would it take more energy to melt a sample of carbon or silicon?
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Molecules London Forces: Organic Compounds The longer the carbon chain, the higher the London Dispersion Forces (the higher the melting point and boiling point) BP( o C) CH 4 -161.6 C 2 H 6 -88.63 C 3 H 8 -42.07 C 4 H 10 -0.5
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Which should have a higher boiling point: C 6 H 14 or C 12 H 26
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Using you knowledge of “like dissolves like”, explain the following trends in solubility. AlcoholSolubility in H 2 O (mol/100 g H 2 O at 20 o C) CH 3 OH∞ CH 3 CH 2 OH∞ CH 3 CH 2 CH 2 OH∞ CH 3 CH 2 CH 2 CH 2 OH0.11 CH 3 CH 2 CH 2 CH 2 CH 2 OH0.030 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 OH0.0058 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 OH0.0008 Explain the following trends in solubility in water
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Emulsifying agents – Mayonaise – Soap
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The Key to the Universe
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You Try: CCl 4 NO 3 - CH 3 ClH 2 CO CH 2 Cl 2 H 2 S Polar Molecules
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KrCl 4 Si 2 H 4 BNCH 3 SiH 2 PH 2 SiS 2 H 2 SO 4 O HOSOH O
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9.(c) Sc 2+ (d) I 2- (e) As 2- 15. Rb + Ba 2+ Te 2- N 3- 16. Al 3+, Mg 2+, Na +, F -, O 2-, N 3- 20.RbFRb 2 TeRb 3 P MgF 2 MgTeMg 3 P 2 CrF 3 Cr 2 Te 3 CrP 22. BeSCs 2 SGa 2 S 3 SrS 24.a) Ir 8+ b) Sc 3+ c) Pt 6+ d) Co 3+ e) Tc 3+ f) Ag +
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27. a) HIb) SeBr 2 c) SiBr 4 d) H 3 As 49. a) PCb) Covc) PCd) Ionic 50. a) PCb) PCd) Ionicd) PC 52. a) N-Hb) Si-Oc) S-FP-Cl
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54.a) trigonal planarb) trigonal pyramid c) lineard) trigonal planar e) trigonal planar 56.a) H 2 Oc) NH 4 +
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a)octahedralh) tetrahedral b)tetrahedrali) trigonal bipyramid c)linearj) trigonal pyramid d)trigonal planark) octahedral e)bentl) linear f)trigonal planarm) linear g)Linearn) linear
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Assessing the Objectives (page 278) a)2, 3 b)Less than 109.5 o c)Trigonal Planar d)Bent e)Linear, 180 o bent, 120 o
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Questions 1. Rank the three liquids from weakest to the strongest forces between their molecules. 2.Discuss how you chose your rankings from the results of the experiment. 3.Is isopropyl alcohol or hexane more like water? Explain, using the results from the experiments. 4.What information did the salt experiment provide about the molecules?
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GAK – NEATNESS!!!!!!! 1.Glue 2.Food coloring 3.Borax solution
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FormulaLewis Dot Ca and O Ca and Br P and H C and F N and F
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Consider the following three chemical bonds: C-O Cl-BrRb-Cl a.Determine the type of bond present in each situation b.In which bond is an electron transferred? c.Draw the Lewis Dot structure of this ionic compound. d.In which bond are electrons unequally shared? e.Identify the element in that bond that the electron spends more time with.
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The element chlorine forms compounds with both strontium and sulfur. a.Write the formula of the compound that forms between strontium and chlorine. b.Draw the Lewis Dot Structure of this compound, indicating whether it is ionic or molecular. c.Write the formula of the compound that forms between sulfur and chlorine. d.Draw the Lewis Dot Structure of this compound, indicating whether it is ionic or molecular. e.Is the structure you drew in (d) linear? Why or why not? f.State the bond angle of the structure in (d).
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Draw the Lewis Dot Structure and predict whether it is a polar or non-polar molecule H 2 O CH 3 CH(OH)CH 3 CH 3 CH 2 CH 2 CH 2 CH 2 CH 3
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WaterIsopropylHexane Alcohol
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Draw Lewis Structures (Ionic) BaF 2 Li 2 O Draw Lewis Structures (Molecular) ClF 3 SiO 3 2- SO 2
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CompoundCentral Atom BeH 2 Tan BH 3 Tan CH 4, NH 3, H 2 OBlack PCl 5 Tan SF 6 Yellow or silver
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7a. Octahedralh. Tetrahedral b.Tetrahedrali. Trigonal bipyramid c.Linearj. Trigonal pyramid d.Trigonal Planark. Octahedral e.Bent Il. Linear f.Trigonal Planarm. Linear g.Linearn. Linear
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1. Covalent, Ionic or Polar Covalent Bonds? a.Ionic b.Covalent c.Polar Covalent d.Ionic e.Ionic f.Polar Covalent g.Polar Covalent h.Ionic
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3a. K + Br - b.Al 3+ 3Cl - c.2Ga 3+ 3O 2- d.2Li + O 2- e.Ca 2+ 2Br - f.Na + OH - g.Ca 2+ 2NO 3 - h.2Na + CO 3 2- i.2Fe 3+ 3SO 4 2- j.Co 4+ 4NO 2 -
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