A. Electronegativity - The ability of an atom to attract electrons to itself in a bond

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Types of Bonds

• 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

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Types of Bonds

• Molecular Compounds (non-metals)
• Sharing of electrons
• Covalent or polar covalent bonds
• Ex H2
• b. Ionic Compounds (metal non-metal)
• Exchange (stealing) of electrons
• Ex NaCl

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Types of Bonds

• 3. Types of bonds
• Electronegatvity Difference
• Example Na-F

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Types of Bonds

• Are the following bonds ionic, polar covalent or
  covalent?
• Ba Br C N
• Be F B H
• O H Be Cl
• P H C H
• O O

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Ionic

• 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-)

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Common Charges
IA IIA IIIA IVA VA VIA VIIA
Hydride H-
Lithium Li Beryllium Be2 Carbide C4- Nitride N3- Oxide O2- Fluoride F-
Sodium Na Magnesium Mg2 Aluminum Al3 Phosphide P3- Sulfide S2- Chloride Cl-
Potassium K Calcium Ca2 Selenide Se2- Bromide Br-
Rubidium Rb Strontium Sr2 Telluride Te2- Iodide I-
Cesium Cs Barium Ba2
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• Complete the following chart

Formula Lewis Dot
K and I
Sr and F
Ba and Cl
Sr and N
Ba and O
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Ionic Solids

1. Not Separate molecules
2. Crystal Lattice Regular 3D pattern in an ionic
   solid

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Ionic Solids
at lattice points
ions at lattice points
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Ions in Water

• Water (molecule) dissolves salt (ionic crystal)

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Other Salts

• Many ionic compounds are called salts
• CaCl2 Calcium Chloride (Quik-Joe)
• NaHCO3 Sodium bicarbonate(Baking soda)
• NaF Sodium Fluoride (toothpaste)
• CaCO3 Calcium Carbonate(Chalk, antacid)
• NaOH Sodium Hydroxide (Drano)
• MgSO4 Magnesium Sulfate(Epsom Salts)
• All big clumps (crystals) of Ions

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What is a Molecule?

• 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

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Old School Lewis Dots

• A. Single Bonds (LD and Stick)
• CH4
• H2O
• (bonded versus lone pairs)

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The Lone Pear(Pair) rides again!
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Old School Lewis Dots

• N and H
• P and F
• Cl and O
• NH2CH3

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Old School Lewis Dots

• You try
• As and H
• N and Br
• CH3CH2OH
• NH2CH2SiCl3
• CH3OCH3

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Old School Lewis Dots

• B. Multiple Bonds
• CO2
• C2H2

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Old School Lewis Dots

• You Try
• HCN
• N2
• AlN
• O2

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Lewis Dots

• 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

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Lewis Dots

• NH3
• NCl3
• SF6
• Br2O
• ClF5

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• You try
• SF4
• KrF4
• Cl2O
• ClF3
• H2SO4

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Lewis Dots

• CO2
• HCN
• CN-
• ICl4-
• NO

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Lewis Dots

• You try
• C2H4
• CO32-
• H3O
• NH4
• PO43-

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Less Than an Octet

• Hydrogen only makes one bond
• Gr I, II and III
• Especially if with a halogen
• BeCl2 BCl3 AlCl3

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More Than an Octet

• Non-Metals starting with P

P S Cl Ar
As Se Br Kr
Te I Xe
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PCl5
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Resonance Structures

• Warm-Up O3
• Definition When a molecule can exist in more
  than one arrangement of electrons
• 1. Atoms dont move
• 2. Only the electrons (double bonds) move
• 3. Also called delocalized bonding

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Resonance Structures

• SPECIAL NOTE
• Oxygen rarely makes three bonds for resonance
  structures. Those structures are not common.

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• PO3-
• HSO3

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Resonance Structures

• Examples
• 1. NO2-, CO32-, CHO2-, HNO3
• 2. Which needs resonance, SO3 or
• SO32-

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Shapes of Molecules

• Valence Shell Electron Pair Repulsion Theory
  (VSEPR)
• VSEPR Valence electron pairs on the central
  atom push as far apart as possible.

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Shapes of Molecules

• 1. Linear (180o)
• BeH2 CO2

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Shapes of Molecules
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Shapes of Molecules

• 2. Trigonal Planar (120o)
• NO3-

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Shapes of Molecules
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Shapes of Molecules

• 3. Tetrahedral (109.5o)
• CH4

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Shapes of Molecules
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Shapes of Molecules

• 4. Trigonal Pyramidal (107o)
• NH3

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Shapes of Molecules
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Shapes of Molecules

• 5. Bent (Type I, 104.5o)
• H2O

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Shapes of Molecules
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Shapes of Molecules
O
H
H
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Shapes of Molecules
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• Bent (Type II, 120o)
• SO2

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• Atoms are bent
• Bond angle 120o

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Shapes of Molecules

• 6. Trigonal Bipyramid (120o, 90o)
• PCl5

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Shapes of Molecules
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Shapes of Molecules

• 7. Octahedral (90o)
• SF6

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Shapes of Molecules
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• DRAW LEWIS DOT STRUCTURES AND PREDICT THE BOND
  ANGLES FOR
• PH3 GeO2
• PCl5 NCl3
• H2S SiH4
• CF4 SO32-
• SeCl6 SO3

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Shapes of Molecules

• Ex All single bonds
• PH3 H2S SiH4
• SeCl6 AsF5 BeCl2
• CH3F HF BF3

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Shapes of Molecules

• Ex Multiple Bonds
• N2
• HCN
• CO2
• H2CO

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• SO22 SO22- SO2
• SO3 SF6

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Shapes of Molecules
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Shapes and Formula?

• 1. Examples
• BeH2
• H2O
• BH3
• NH3
• 2. There is no relationship between formula and
  shape

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• PO2- PO3- PO33-
• PO43- XeF4

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Naming Molecules

• Household Molecules
• H2O
• HCl
• NH3
• H2SO4

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Polar Molecules

• 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
• 3. d-/ d Partial (not full) charges

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• H2 H2O
• CH4 H2CO (C is the center)

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• H2 H2O
• CH4 H2CO

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• BeCl2
• NH3
• CO2
• CSO
• HCN (triple bond)

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• CCl4
• CH3Cl
• CH2Cl2
• CHCl3
• HBeCl
• HBr

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Polar Molecules

• CH3Cl CH2Cl2
• CHCl3 HBeCl HBr

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Lewis Dot Shape Polar or Non-polar molecule?
H2O
NH3
CH3Cl
CH3CH2OH
SO2
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• Hydrogen Bonding
• a. Water Beading
• b. SurfaceTension
• c. Ice
• d. DNA
• e. Miscibility (NH3, ethanol)
• f. Immiscibility (Water and Oil)

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Water Beading
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Surface Tension

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Surface Tension

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Ice

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Ice

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Boiling Point

• Generally increases with increasing molar mass
• H2O unusually high - H-bonding

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DNA

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DNA

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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Miscibility

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Miscibility

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Miscibility

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Miscibility

• Water, alcohol

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Miscibility

• Water, alcohol

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Miscibility

• 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?

O CH3CCH3
Acetone
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London Dispersion Forces

• Very weak force
• Caused by temporary imbalances in electrons

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London Forces Inorganic Molecules

• More electrons, more chance for temporary dipole

Boiling Point Table Boiling Point Table Boiling Point Table Boiling Point Table Boiling Point Table Boiling Point Table
Halogen Molar Mass BP(oC) Noble Gas Atomic Mass BP(oC)
F2 (g) 38.0 -188 He 4.0 -268
Cl2 (g) 71.0 -35 Ne 20.2 -246
Br2 (l) 159.8 59 Ar 39.9 -186
I2 (s) 253.8 185 Kr 83.8 -152
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• Consider the following molecules
• Te2 S2 O2 Se2
• Rank them from weakest to strongest London forces
  
• Which should have the highest boiling point?
  Which should have the lowest?
• Would it take more energy to melt a sample of
  carbon or silicon?

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London Forces Organic Compounds

• The longer the carbon chain, the higher the
  London Dispersion Forces (the higher the melting
  point and boiling point)
• BP(oC)
• CH4 -161.6
• C2H6 -88.63
• C3H8 -42.07
• C4H10 -0.5

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• Which should have a higher boiling point
• C6H14 or C12H26

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Explain the following trends in solubility in
water

• Using you knowledge of like dissolves like,
  explain the following trends in solubility.

Alcohol Solubility in H2O (mol/100 g H2O at 20oC)
CH3OH 8
CH3CH2OH 8
CH3CH2CH2OH 8
CH3CH2CH2CH2OH 0.11
CH3CH2CH2CH2CH2OH 0.030
CH3CH2CH2CH2CH2CH2OH 0.0058
CH3CH2CH2CH2CH2CH2CH2OH 0.0008
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• Emulsifying agents
• Mayonaise
• Soap

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The Key to the Universe
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Polar Molecules

• You Try
• CCl4 NO3-
• CH3Cl H2CO
• CH2Cl2 H2S

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• KrCl4 Si2H4
• BN CH3SiH2PH2
• SiS2 H2SO4
• O
• H O S O H
• O

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• (c) Sc2 (d) I2- (e) As2-
• 16. Al3, Mg2, Na, F-, O2-, N3-
• RbF Rb2Te Rb3P
• MgF2 MgTe Mg3P2
• CrF3 Cr2Te3 CrP
• a) Ir8 b) Sc3 c) Pt6 d) Co3
• e) Tc3 f) Ag
• 27. a) HI b) SeBr2 c) SiBr4 d) H3As
• 49. a) PC b) Cov c) PC d) Ionic
• 50. a) PC b) PC d) Ionic d) PC
• 52. a) N-H b) Si-O c) S-F P-Cl

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• a) trigonal planar b) trigonal pyramid
• c) linear d) trigonal planar
• e) trigonal planar
• a) H2O c) NH4

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1. octahedral h) tetrahedral
2. tetrahedral i) trigonal bipyramid
3. linear j) trigonal pyramid
4. trigonal planar k) octahedral
5. bent l) linear
6. trigonal planar m) linear
7. Linear n) linear

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• Assessing the Objectives (page 278)
• 2, 3
• Less than 109.5o
• Trigonal Planar
• Bent
• Linear, 180o bent, 120o

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• Questions
• Rank the three liquids from weakest to the
  strongest forces between their molecules.
• Discuss how you chose your rankings from the
  results of the experiment.
• Is isopropyl alcohol or hexane more like water?
  Explain, using the results from the experiments.
• What information did the salt experiment provide
  about the molecules?

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• GAK NEATNESS!!!!!!!
• Glue
• Food coloring
• Borax solution

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Formula Lewis 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-Br Rb-Cl
• Determine the type of bond present in each
  situation
• In which bond is an electron transferred?
• Draw the Lewis Dot structure of this ionic
  compound.
• In which bond are electrons unequally shared?
• 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.
• Write the formula of the compound that forms
  between strontium and chlorine.
• Draw the Lewis Dot Structure of this compound,
  indicating whether it is ionic or molecular.
• Write the formula of the compound that forms
  between sulfur and chlorine.
• Draw the Lewis Dot Structure of this compound,
  indicating whether it is ionic or molecular.
• Is the structure you drew in (d) linear? Why or
  why not?
• 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 H2O CH3CH(O
H)CH3 CH3CH2CH2CH2CH2CH3
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• Water Isopropyl Hexane
• Alcohol

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• Draw Lewis Structures (Ionic)
• BaF2 Li2O
• Draw Lewis Structures (Molecular)
• ClF3 SiO32- SO2

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Compound Central Atom
BeH2 Tan
BH3 Tan
CH4, NH3, H2O Black
PCl5 Tan
SF6 Yellow or silver