Week 5Quarter 3

Unit 4: Bonding & Nomenclauture

(Resource: Chapter 7, 8, 9)

Agenda

• HW:

• Simulation: Bonding Simulation (PBS and ACT) Part 2 Covalent Bonding

Compounds

• EXP Drawing Covalent Molecules

• Read Ch 7, 8, 9 and PP7, 8, and 9Note: exclude Hybrid Orbitals

• Unit 4 Exam (Bonding) March 10, 2020

NOTE: NO assessment on Hybrid

orbitals, properties, and IMF/s

• ICA:

• Quiz: Nomenclature 2 - 5

• EXP Drawing Covalent

Molecules(One Note: Content Library: Unit 4: Topic 2c:

EXP)

• Pilot: Pearson • PhET Simulations

• EXP Properties Lab

• Virtual Lab

Learning Goals II

Topics• Molecules: Nonmetals and Nonmetals

elements/compounds; Polar or Nonpolar

• Use Electronegative Values (Polar vs. Nonpolar)

• Covalent - Polar vs. Nonpolar Bonds

• Molecules – Polar vs. Nonpolar Molecules

• Properties of Ionic vs. Covalent vs. Metallic (vs. network solids) (p. 244)

• Bond Dissociation Energy

• Intermolecular Forces (IMF)

Additional Tools/Skills• VSEPR (p. 232)

• Diatomic Elements (p. 222)

• Polyatomic Ions (p. 257)

• Bond Types (p. 238)

• Polar Molecules (p. 238)

• Reference Packet

Problem Pools

Chapter Questions Standardized Test Prep

7 4, 7, 8, 10, 12, 19, 22, 25, 27, 31, 35, 37, 40, 41, 42, 51, 53, 65,

78, 79***Exclude ionic/metallic crystalline structures. Just enjoy the beauty of the structures

and understand general concept of + and – attractions.

STP all

*** same notes

8 3, 4, 5, 11, 16, 18, 21, 22, 30, 31, 36, 37, 40, 41, 45, 48, 50, 52,

54, 58, 59, 60,

61, 63, 68, 69, 74

STP all

9 43, 44, 45, 46, 51, 53, 57, 58, 60, 65, 68, 70, 81, 83, 84 STP all

Suggested problems from the textbook "Chemistry" (Prentice Hall). These are only from the Assessment and Standardized Test Prep found at the end of the chapters. There are also questions available at the end of each section (in the textbook) for more practice.

Additional Resource: Pearson

EasyBridgehttps://launchpad.classlink.com/Issaquah

Pilot: Pearson

Classlink: Issaquah

Easy Bridge

Investigation 3

Experience 3 (Covalent)

ReviewMolecules and their Covalent Bonds

Activity:

Bonding Simulations

Part 2 Covalent Bonding

ACS:

https://teachchemistry.org/classroom-resources/ionic-covalent-bonding-simulation

PBS:

https://kcts9.pbslearningmedia.org/resource/lsps07.sci.phys.matter.ionicbonding/ionic-

bonding/

https://kcts9.pbslearningmedia.org/resource/lsps07.sci.phys.matter.covalentbond/covalent-

bonding/

Learning Goal

Learning Goal

WHY do certain substances have high melting point or are more soluble in water, or can conduct electricity....WHY?

because

Molecular Geometry determines Bond Polarity which determines Molecular Polarity which

determines Attraction which determines Properties

HOW: Therefore, we will learn how to know if a molecule is attractive (polar) or sometimes attractive (nonpolar).

How To: Identify the Molecular Geometry

• Step 1: Just know how the atoms attach.

• Diatomic molecules are always linear.

• The central atom must be able to make more than 1 bond. Thus, can never be Hydrogen or a Halogen.

• Always show ALL unshared (lone pairs) in a molecule.

• Use a line to represent shared pairs.

• Step 2: Use AXE system to identify the molecular geometry.

• VSEPR

• Unshared Pairs of Electrons take up more space than shared electrons.

• Molecular Geometry vs. Electron Geometry

Step 1: Just know how the atoms attach.

• Step A: Count up the total valence electrons in the molecule.

• Step B: Set up the atoms using single bonds. (1 line = 1 bond = 2 electrons)

• Step C: Use the duet/octet rule to make each atom “happy” (aka. Stable)

• Lone pairs of electrons should be included.

• Step D: Recount all the electrons in the molecule and it should equal the total valence electrons identified in Step A.

• Step E: If there are too many electrons in the Lewis Structure, remove all unshared electrons and add a double (or triple) bond and start with Step C again.

HONC Rule

This generally works for these elements.

However, there are always exceptions. For example, Oxygen can form a Triple Bond with Carbon.

Also, Sulfur and Phosphorus and Boron are exceptions to the Octet Rule and thus have either less or more bonds than expected.

NOTE: How do you know which atom is the central atom??? Use the HONC rule. Should be an atom that can form at least 2 or more bonds.

Diatomic Molecules

Step 2: Use AXE system to identify the molecular geometry.

• A Central Atom

• X (or B) Other Atoms

• E Unshared Electron Pairs on the CENTRAL atom

• Note: At this point the presence or absence of lone pairs on

the central atom is what affects the molecular shape.

VSEPR

A Central Atom

X (or B) Other Atoms

E Unshared Electron Pairs

https://i0.wp.com/www.compoundchem.c

om/wp-content/uploads/2014/11/VSEPR-

Shapes-of-Molecules.png?ssl=1

Molecular Geometry

•Molecular Geometry

•Lone pairs/ Nonbonding electrons/ unshared pairs**

•Electronegativity

•Dipole moment

•Polar vs. Nonpolar bonds

•Polar vs. Nonpolar molecules

VSEPR

https://i0.wp.com/www.compoundc

hem.com/wp-

content/uploads/2014/11/VSEPR-Shapes-of-Molecules.png?ssl=1

Resource: Compound Interest

Experience 3:

Covalent bonds

Read the pages on Molecular

Geometry and answer the CCC

question in the eText or the class

copy.

Handout: Calculate Bond Polarity

Resource: PhET Simulation

"Molecule Shape"

PhET: Molecule Shapes

Use the PhET Simulation to see the molecule in 3-D. This is great when you compare NH3 and BF3. You can actually see that BF3 is planar.

Their shapes are determined by all the lone (nonbonding) and bonding electron pairs around the central atom.

PhET: Molecule Shapes

This will show up on the PhET.

However, you will only be asked about the Molecular Geometry.

PhET: Molecule Shapes

This will show up on the PhET.

However, you will only be asked about the Molecular Geometry.

Electron Geometry Molecular Geometry

How to: Determine Bond Polarity

How to: Determine Bond Polarity

Tool: Electronegativity

Where are the

electrons?

To determine if the bond

and, ultimately the molecule, is

polar, we need to know where the

electrons are more likely to be

found.

Polar Bond

Dipole moments occur when there

is a separation of charge.

They can occur between two ions in

an ionic bond or between atoms in a

covalent bond

Dipole moments arise from

differences in electronegativity. The

larger the difference in

electronegativity, the larger

the dipole moment.

Nonpolar

How to: Determine Molecule Polarity

Activity:

Building Molecules

1. Build two diatomic molecules (nonpolar and polar) and two polyatomic molecules (nonpolar and

polar).

2. Take a photo of the diatomic molecules together and the polyatomic molecules together.

3. Label the images with the following:

Chemical Symbols

Electronegativity Values

Dipole moments on Bonds

Use the d- and d+ symbols

Overall Dipole moment

4. Caption the images with the names of the molecules and their overall polarity.

How to: Determine Molecule Polarity

How to: Determine Molecule Polarity

Do you now understand

this image about

Molecules?

Polar vs. Nonpolar

Make sure you also know how to

draw or interpret Bohr models as

well as Lewis Dot Structures.

More Practice &

Understanding

PhET: Molecular Polarity

• Predict how changing electronegativity will affect the bond polarity.

• Explain the relationship between the bond dipoles and the molecular dipole.

• Determine if a non-polar molecule can contain polar bonds.

• Describe how the ABC bond angle effects the molecular dipole.

• Compare the behavior of non-polar and polar molecules in an external electric field.

• What does it mean?

• How it behaves in an

electric field.

How to: Determine Molecule Polarity

Polar Molecules

How does being polar affect their

properties?

SIDE NOTEHow is Bond Length determined? Hint: Coulombic Attraction/Repulsion

PE Diagram: Bond

Formation

If the hydrogen atoms are too far

apart, attractions are weak and no

bonding occurs. If the atoms are

too close, strong repulsions occur.

The minimum potential energy

occurs at an optimal distance

between the nuclei. This distance is

the bond length.

Q/AQuestions and Answers