Warm Up…what do you remember?

1. Why do bonds form?

2. What is the difference between ionic and covalent bonds?

Warm Up…what do you remember?

Why do bonds form?

What is the difference between ionic and covalent bonds?

Draw the Lewis Structures and show the behavior of the electrons.

Sodium and Bromine

Fluorine and oxygen

(you will need 2 F)

Covalent Compounds

Nonmetal bonding with another nonmetal

Electronegativity difference less than 1.67

Electrons being shared

Formation of Covalent Bond

Bond Stability

Properties of Covalent Compounds

– low melting point– low boiling point– many are gas and liquid at room temp– typically do not conduct electricity when

dissolved in water

This is due to the fact that forces of attraction between molecules are much weaker when the electrons are being shared.

Ionic vs covalent

Visual Concepts

Warm Up- Write the correct formulas from the names.

1.Copper (III) iodide

2.Sodium oxide

3.Calcium nitride

4.Chromium (II) oxide

5.Iron (III) sulfide

When do we need to use Roman Numerals in the name of an ionic compound?

Discuss Signs…

Draw the MO diagram for Carbon and Oxygen…

What do the electrons do??

Do we need to worry about covalent compounds being neutral?

Are the electrons being shared equally??

Polar or Nonpolar?

Nonpolar- electrons are shared equally.

Polar- electrons are not shared equally.

Octet Rule

• Noble gases: have filled valence shells =

2 (He) or 8 e-

• Octet Rule tells us that chemical compounds tend to form so that atoms obtain an octet of e- in its highest energy level.

Visual Concepts

Lewis Structure Rules

1. Add up total number of valence e- 2. Pick central atom and create the bonds3. Surround the adjacent atoms.4. Put extra electrons on the central atom.5. Beg, borrow or steal so that all the atoms are

stable (have a complete octet).6. Make sure the number of valence e- you

started with are the number you used!

Lets do…

CH4

SiF4

NCl3

Draw the Lewis Structures for the following molecules…CH3F

SiCl4

How many shared electrons?

How many unshared electrons?

Are the electrons shared equally?

Dipoles

Indicate polarity- dipole points to the most electronegative atom!

Show the unequal distribution of charge

Exceptions

• Boron trifluoride BF3

• PF5 and SF6 can expand the shell and share more electrons. (10 and 12 respectively)

Diatomic Molecules

You must memorize these!!

H2 N2 O2 F2 Cl2 Br2 I2 (At2)

Magnificent 7—

I won’t hold you responsible for astatine, just know that trends in a group apply!

Naming Covalent Compounds

Covalent compounds are molecules or molecular compounds…

Indicate the number of each atom using prefixes…..

…change the end of the name to “ide”

Covalent Prefixes

Use the prefixes!

1- mono 6- hexa

2- di 7- hepta

3- tri 8- octa

4- tetra 9- nona

5- penta 10- deca

Examples: NO

SiCl4

Practice

Formulas to names

1. SO3

2. ICl33. PBr5

4. CO

5. CO2

Names to formulas

1. Carbon tetrachloride

2. Dinitrogen monoxide

3. Dinitrogen tetroxide

4. Phosphorus triiodide

5. Sulfur heptafluoride

Homework- You can do these!

H2Se

CH2Cl2Silicon Tetrachloride

HCl

Fluorine

CH4

NH3

Silicon Tetrachloride

Chlorine

Warm Up- Thursday

Write the names from the formulas…

1. BaSO4

2. MnO4

3. SiO2

4. PO

5. NiPO4

Questions on Homework?

Lewis Structure WS…

Naming Covalent Compounds WS

Forming Multiple Bonds

CO2

N2O

Multiple Covalent Bonds• Bond length and strength

– Triple bonds are the shortest (pm) and have the most Energy (kJ/mol)

– Single bonds are the longest (pm) and have the least amount of Energy (kJ/mol)

Sigma and Pi bonds

• Sigma ( bonds are single bonds

• Pi ( bonds are the bonds that follow in a multiple bond situation

Now you try…

CO

Oxygen

Polyatomic ions

Draw the Lewis Structures for the following polyatomic ions.

Phosphate

Hydroxide

LS of ions are indicated using [ ] and charge

Polyatomic ions

Examples

Warm Up: Draw the Lewis Structures and indicate the dipoles…

1. CH2F2

2. F2

3. NO31-

Indicate the number of shared and unshared pairs on each molecule.

.

Resonance Structures

• Some molecules cannot be correctly identified by a single Lewis structure

• When you can draw two mirror images, you probably have a resonance structure– For example: Ozone O3

Visual Concepts

Draw the Resonance Structures for

Selenium Trisulfide

Questions on the LS WS??

How did you do on the polyatomic ions??

Acids to memorize…

Hydrochloric- HCl

Acetic Acid- HC2H3O2

Nitric Acid- HNO3

Sulfuric Acid- H2SO4

Carbonic Acid- H2CO3

Phosphoric Acid- H3PO4

Building Covalent Molecules Activity

1. Fold paper so that you have 6 squares on each page.

2. Write the compound formulas in each box as indicated on the board.

Just a few things from last semester…

1. Your feedback is very important to me!a. Students like- CB, notes, activitiesb. Mixed reactions- POGILS, Projects and homework amount.c. Students didn’t like- IB cut and paste, worksheet assignment/collection.

2. Performance Assessment / Final.3. Writing in science.4. What’s new in the room?

Building Covalent Molecules Activity

1. Draw the Lewis Structure for each molecule.

2. Build the molecule using the kits.3. Determine the Electronegativity of each

atom and determine bond polarity- draw the dipoles on LS.

4. Draw the 3-D molecule.5. Determine the molar mass of each

molecule.

Warm Up-

Write the names from the formulas…

1. BaSO4

2. MnO4

3. SiO2

4. PO

5. NiPO4

Be sure you are reviewing your Ionic Bonding… all is fair game for the test next week.

Review Questions?

Test

Warm Up

Determine the formula

1.Calcium hydroxide

2.Vanadium (IV) oxide

3.Phosphorus tribromide

4.Chlorine

5.Zinc sulfide

Determine the name

1.SrO

2.FePO4

3.PO3

4.HC2H3O2

5.O2

How did you do?

Determine the formula

1.Ca(OH)2

2.VO2

3.PBr3

4.Cl25.ZnS

Determine the name

1.Strontium oxide

2.Iron(III) phosphate

3.Phosphorus trioxide

4.Acetic acid

5.Oxygen

Just a few things from last semester…

1. Your feedback is very important to me!a. Students like- CB, notes, activitiesb. Mixed reactions- POGILS, Projects and homework amount.c. Students didn’t like- IB cut and paste, worksheet assignment/collection.

2. Performance Assessment / Final.3. Writing in science.4. What’s new in the room?

Molecular Geometry

VSEPR

Valence Shell, Electron

Pair Repulsion

Theory

VSEPR

• How a molecule “looks” in real space (3D).

• Shape is based upon electron domains (where electrons are).

Bonds (doubles/triples count as one domain)

Unshared electron pairs- actually take more space.

You need to remember…

–Electron domains repel each other.

–Unshared pairs repel more than bonding pairs.

–Domains orient themselves as far away from each other as possible.

VSEPR

Let’s use balloons to figure out the molecular geometry of various

compounds!

Here are some video clips that will

show it to you again!

• Development of bond angles

Visual Concepts

• Lone pair geometry

Visual Concepts

Guess the shape!

Polarity- Physical Property

Look at the entire molecule-

If there is an unequal distribution of charge (dipoles or a bunch of electrons in one spot).

POLAR

If all the bonds are nonpolar or the molecule is symmetrical (even if it has dipoles), it is

NONPOLAR

Let’s Discuss These!

Let’s revisit the molecules you built Tuesday…

1. Shape and Bond Angles?

2. Determine the overall polarity.

You can keep these activities to study… be sure to bring them to hand in on test day!

Is Polarity a Physical or Chemical Property?

Polarity is important in determining the reactivity of various molecules.

It helps us understand the interaction between molecules (intermolecular forces).

It also determines the solubility of the molecule.

Warm Up – Tues. Honors

Draw the LS and predict the molecular geometry and bond angles for the following molecules.

SO22- SiCI4 BCl3

Intramolecular Forces

We have spent a month talking about intramolecular forces… the forces between atoms.

What are they called?

Intermolecular Forces

Forces of Attraction between Molecules

These forces affect the physical properties of compounds

Melting and Boiling Points

Volatility

Solubility

What does Volatility mean?

• Volatile Liquid Demo

• Let’s try to figure out why the alcohol this guy uses is more volatile than water.

Ethanol- C2H6O Draw the LS

Different types of Intermolecular Forces

Dipole-Dipole Force- The negative region of one molecule is attracted to the positive region of a different molecule.

HCl, NH3

Induced dipole - When a polar molecule causes a nonpolar molecule to become polar (temporary).

Visual Concepts

Different types of Intermolecular Forces

• London dispersion - result from the constant motion of electrons and the creation of instantaneous dipoles.

• LD Video

Super Important!

• Hydrogen Bonding- When a hydrogen atom (bonded to a highly electronegative atom) attracts an unshared pair of electrons from the atom of a nearby EN atom. Video 1- Basic

Video 2- A little more deep!

What elements with Hydrogen form H bonds?

Hydrogen Bonding

Get into your small groups and discuss why ethanol is more

volatile than water.

Metallic Bonding

• This is an extremely strong bond• Delocalized electrons

Gives metal: luster, malleability, ductility, conduct electricity and heat

Polar Molecule

• One end negative, one end positive

Dipole

• Molecule that has two poles

• Is created by equal but opposite charges that are separated by a short distance

Look at the Polarity of the Molecule

Memorize!

• Shapes and angles– Linear 180o

– Trigonal planar 120o

– Tetrahedral 109.5o

– Trigonal pyramidal 107.5– Bent 104.5– Trigonal bipyramidal 90o 120o

– Octahedral 90o

Metals

Share a sea of electrons…

Explains why so many of them are good conductors of electricity.

Alloys

• Combination of metals – Bronze: copper and tin– Brass: zinc and copper– Coin metal: copper and nickel– Solder: lead and tin

Substitutional Alloy

• Some of the main metal atoms are replaced by other metal atoms of similar size.

• An example is brass where one-third of the atoms of the host copper are replaced with zinc atoms.

Interstitial Alloy

• Formed when some of the holes in the closest packed metal structure are occupied by small atoms.

• Steel is an interstitial alloy, containing carbon atoms in the holes of an iron crystal.

Stainless steel is a mixture of Iron, Chromium and Carbon.

What kind of Alloy would it be?

Questions on the Review???

I will post review answers on-line… feel free to come see me to answer questions.

Be sure to look over your ionic bonding WS.

Naming Game (Time Permitting)