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

1. Periodic Trends (link to size)Metals – Low ElectronegativityNon- Metals – High Electroneg

The smaller the atom, the higher the electronegativity

Types of Bonds

a. 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

Types of Bonds

3. Types of bondsElectronegatvity Difference

Example: Na-F

Types of Bonds

Are the following bonds ionic, polar covalent or covalent?

Ba – Br C – NBe – F B – HO – H Be – ClP – H C – HO – O

Types of Bonds

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

IA IIA IIIA IVA VA VIA VIIA

HydrideH-

LithiumLi+

BerylliumBe2+

CarbideC4-

NitrideN3-

OxideO2-

FluorideF-

SodiumNa+

MagnesiumMg2+

AluminumAl3+

PhosphideP3-

SulfideS2-

ChlorideCl-

PotassiumK+

CalciumCa2+

SelenideSe2-

BromideBr-

RubidiumRb+

StrontiumSr2+

TellurideTe2-

IodideI-

CesiumCs+

BariumBa2+

Common Charges

Complete the following chart:Formula Lewis Dot

K and I

Sr and F

Ba and Cl

Sr and N

Ba and O

Complete the following chart:Formula Lewis Dot

K and S

Al and O

Na and Br

Ca and O

1. Not Separate molecules2. Crystal Lattice – Regular 3D pattern in an

ionic solid

Ionic Solids

Ionic Solids

at lattice points ions at lattice points

1. Water (molecule) dissolves salt (ionic crystal):

Ions in Water

Molecules

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

Other Salts

• 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?

A. Single Bonds (LD and Stick)CH4

H2O

(bonded versus lone pairs)

Old School Lewis Dots

The Lone Pear(Pair) rides again!

N and HP and FCl and ONH2CH3

Old School Lewis Dots

You try:As and HN and BrCH3CH2OH

NH2CH2SiCl3

CH3OCH3

Old School Lewis Dots

As and ClC and BrCH3CH2NH2

CH3OCH2CH3

B. Multiple BondsCO2

C2H2

Old School Lewis Dots

You Try:HCNN2

AlN

O2

Old School Lewis Dots

Rules1. Sum all valence electrons, including

charges2. Single Bonds3. Outer atoms get an octet except H4. Center gets rest even if it violates the octet5. Double/triple bonds if center atom still

does not have an octet

Lewis Dots

NH3

NCl3

SF6

Br2O

ClF5

Lewis Dots

You try:SF4

KrF4

Cl2O

ClF3

H2SO4

Warm-Up:

CH3CH2NH2

SeF4

KrCl4

H2O2

BaCl2 (this is an ionic cmpd)

CO2

HCNCN-

ICl4-

NO+

Lewis Dots

CO32-

H3O+

NH4+

PO43-

SO2

• Hydrogenonly makes one bond• Gr I, II and III• Especially if with a halogen

BeCl2 BCl3 AlCl3

Less Than an Octet

• Non-Metals starting with P

More Than an Octet

P S Cl Ar

As Se Br Kr

Te I Xe

PCl5

Warm-Up: O3

Definition – When a molecule can exist in more than one arrangement of electrons1. Atoms don’t move2. Only the electrons (double bonds) move3. Also called “delocalized bonding”

Resonance Structures

Si2H4

AsO43-

CS32-

H3S+

PH4+

SPECIAL NOTE:

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

Resonance Structures

PO3-

HSO3+

Examples1. NO2

-, CO32-, CHO2

-, HNO3

2. Which needs resonance, SO3 or

SO32-

Resonance Structures

• Valence Shell Electron Pair Repulsion Theory (VSEPR)

• VSEPR – Valence electron pairs on the central atom push as far apart as possible.

Shapes of Molecules

1. Linear (180o)BeH2 CO2

Shapes of Molecules

Shapes of Molecules

2. Trigonal Planar (120o)NO3

-

Shapes of Molecules

Shapes of Molecules

3. Tetrahedral (109.5o)CH4

Shapes of Molecules

Shapes of Molecules

4. Trigonal Pyramidal (~107o)NH3

Shapes of Molecules

Shapes of Molecules

5. Bent (Type I, ~104.5o)H2O

Shapes of Molecules

Shapes of Molecules

Shapes of Molecules

OH H

Shapes of Molecules

Bent (Type II, 120o)SO2

•Atoms are bent•Bond angle = 120o

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

Shapes of Molecules

Shapes of Molecules

7. Octahedral (90o)SF6

Shapes of Molecules

Shapes of Molecules

DRAW LEWIS DOT STRUCTURES AND PREDICT THE BOND ANGLES FOR:

PH3 GeO2

PCl5 NCl3

H2S SiH4

CF4 SO32-

SeCl6 SO3

Ex: All single bonds:PH3 H2S SiH4

SeCl6 AsF5 BeCl2

CH3F HF BF3

Shapes of Molecules

Ex: Multiple Bonds:N2

HCNCO2

H2CO

Shapes of Molecules

SO22+ SO2

2- SO2

SO3 SF6

Shapes of Molecules

1. Examples:BeH2

H2O

BH3

NH3

2. There is no relationship between formula and shape

Shapes and Formula?

PO2- PO3

- PO33-

PO43- XeF4

Household Molecules H2O

HClNH3

H2SO4

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

H2 H2O

CH4 H2CO (C is the center)

H2 H2O

CH4 H2CO

BeCl2

NH3

CO2

CSO

HCN (triple bond)

CCl4 CH3ClCH2Cl2

CHCl3

HBeClHBr

CH3Cl CH2Cl2

CHCl3 HBeCl HBr

Polar Molecules

Lewis Dot Shape Polar or Non-polar molecule?

H2O

NH3

CH3Cl

CH3CH2OH

SO2

Hydrogen Bondinga. Water Beadingb. SurfaceTensionc. Iced. DNAe. Miscibility (NH3, ethanol)f. Immiscibility (Water and Oil)

Water Beading

Surface Tension

Surface Tension

Ice

Ice

MoleculesBoiling Point• Generally

increases with increasing molar mass

• H2O unusually high - H-bonding

DNA

DNA

DNA is TWO molecules

that are hydrogen

bonded (like a zipper)

DNA

Human Genome Project

• DNA in one cell = 1 meter• DNA in all your cells = 93,000,000 miles

Miscibility

•“Like dissolves like.”

•Polar dissolves Polar

•Water, ammonia

Miscibility

Miscibility

Miscibility

Miscibility

Miscibility

•Water, alcohol

•Water, alcohol

•Water, alcohol

Miscibility

•Water, alcohol

Miscibility

•Non-Polar dissolves Non-Polar

•oil paint, thinner

Miscibility

Would acetone (shown below) dissolve in water?

Acetone

:O: ||CH3CCH3

MoleculesLondon Dispersion Forces

• Very weak force• Caused by temporary imbalances in electrons

MoleculesLondon Forces: Inorganic Molecules• More electrons, more chance for temporary

dipole

Boiling Point TableHalogen Molar

MassBP(oC) Noble

GasAtomic 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

Consider the following molecules:

Te2 S2 O2 Se2

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?

MoleculesLondon 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 -161.6C2H6 -88.63C3H8 -42.07C4H10 -0.5

Which should have a higher boiling point:

C6H14 or C12H26

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

Alcohol Solubility in H2O (mol/100 g H2O at 20oC)

CH3OH ∞

CH3CH2OH ∞

CH3CH2CH2OH ∞

CH3CH2CH2CH2OH 0.11

CH3CH2CH2CH2CH2OH 0.030

CH3CH2CH2CH2CH2CH2OH 0.0058

CH3CH2CH2CH2CH2CH2CH2OH 0.0008

Explain the following trends in solubility in water

Emulsifying agents– Mayonaise– Soap

The Key to the Universe

You Try:

CCl4 NO3-

CH3Cl H2COCH2Cl2 H2S

Polar Molecules

KrCl4 Si2H4

BN CH3SiH2PH2

SiS2 H2SO4

OH O S O H

O

9. (c) Sc2+ (d) I2- (e) As2- 15. Rb+ Ba2+ Te2- N3-

16. Al3+, Mg2+, Na+, F-, O2-, N3-

20.RbF Rb2Te Rb3P

MgF2 MgTe Mg3P2

CrF3 Cr2Te3 CrP

22. BeS Cs2S Ga2S3 SrS

24.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) PC52. a) N-H b) Si-O c) S-F P-Cl

54.a) trigonal planar b) trigonal pyramidc) linear d) trigonal planare) trigonal planar

56.a) H2O c) NH4+

a) octahedral h) tetrahedralb) tetrahedral i) trigonal bipyramidc) linear j) trigonal pyramidd) trigonal planar k) octahedrale) bent l) linearf) trigonal planar m) linearg) Linear n) linear

Assessing the Objectives (page 278)a)2, 3b)Less than 109.5o

c) Trigonal Planard)Bente)Linear, 180o bent, 120o

Questions1. 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?

GAK – NEATNESS!!!!!!!1.Glue2.Food coloring3.Borax solution

Formula Lewis Dot

Ca and O

Ca and Br

P and H

C and F

N and F

Consider the following three chemical bonds:

C-O Cl-Br Rb-Cla. Determine the type of bond present in each

situationb.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.

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).

Draw the Lewis Dot Structure and predict whether it is a polar or non-polar molecule

H2O

CH3CH(OH)CH3

CH3CH2CH2CH2CH2CH3

Water Isopropyl HexaneAlcohol

Draw Lewis Structures (Ionic)

BaF2 Li2O

Draw Lewis Structures (Molecular)

ClF3 SiO32- SO2

Compound Central Atom

BeH2 Tan

BH3 Tan

CH4, NH3, H2O Black

PCl5 Tan

SF6 Yellow or silver

7a. Octahedral h. Tetrahedral

b.Tetrahedral i. Trigonal bipyramid

c. Linear j. Trigonal pyramid

d.Trigonal Planar k. Octahedral

e. Bent I l. Linear

f. Trigonal Planar m. Linear

g.Linear n. Linear

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

3a. K+ Br-

b.Al3+ 3Cl-

c. 2Ga3+ 3O2-

d.2Li+ O2-

e. Ca2+ 2Br-

f. Na+ OH-

g.Ca2+ 2NO3-

h.2Na+ CO32-

i. 2Fe3+ 3SO42-

j. Co4+ 4NO2-

http://www.youtube.com/watch?v=WaPxTAeW5e8