8th Chemistry - Metallic Bonding and Intermolecular Forces

St. George's College

Subject: 8th CHEMISTRY

Teacher's notes

Objectives

Class: Metallic Bonding

Vocabulary

and Intermolecular Forces Link and Learn

Date: September 7th In‐Class Survey

2009

Prepared by

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8th Milton A ‐ Metallic Bonding and Intermolecular Forces Name

Oral Intervention

Sergio María Fernanda Alejandra Almendra Anna Paula Sandra E‐C Maia María Belén Alfredo Kinley Arianne Sandra M. Fiorella Rodrigo Giulia Jaime Stefano Bruno

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8th Milton Alpha ‐ Metallic Bonding and Intermolecular Forces Name

Oral Intervention

Marcelo Antonella Paulo Alejandro Brenda Diego Gabriel Valeria Cristina Giuliana Joshua María Gracia Gonzalo N. Paolo Gonzalo R. Giorgio Nicolás María Claudia

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Let's remember previous learned concepts...

What are the types of Chemical Bonding?

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New knowledge beginning......

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Metallic Bonds • Metals can be shaped because of the presence of a metallic bond.

• A metallic bond is a bond formed by the attraction between positively charged metal ions and the e‐ in the metal.

• Bonding in metals is a result of the metal atoms being so close to one another that their outermost energy levels overlap. This overlapping allows valence e‐ to move throughout the metal.

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Properties of Metals • Metallic bonding is what gives metals their particular properties (electrical conductivity, malleability, and ductility).

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Bending without Breaking • When a piece of metal is bent, some of the metal ions are forced closer together.

• Positively charged ions repel one another.

• However, positive ions in a metal are always surrounded by and attracted to the e‐ in the metal, even if the metal ions move.

• The e‐ constantly move around and between the metal ions, maintaining the metallic bonds no matter how the shape of the metal changes; so metal objects can be bent without being broken.

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INTERMOLECULAR FORCES

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INTERMOLECULAR FORCES • Forces bonding atoms in a molecule are due to chemical bonding.

• Forces holding together are called intermolecular forces.

• The energy required to break molecules apart is much smaller than a typical bond‐energy, but intermolecular forces play important roles in determining the properties of substances.

• intermolecular forces are especially important in determining the interactions between biomolecules.

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INTERMOLECULAR FORCES

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Molecular Dipoles • Certain molecules have an uneven distribution of positive and negative charges on its atoms.

For example: WATER.

• Depending on the dipole moment, molecular dipoles can be: PERMAMENT DIPOLES: when two atoms in a molecule have significantly different electronegativities.

Example: HCl. INSTANTANEOUS DIPOLES: whwn inside a molecule, electrons are more concentrated on one side than another. Example: London Forces INDUCED DIPOLES: when a molecule with a permanent dipole repels another molecule's electrons, inducing a dipole moment in that molecule.

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Dispersion Forces • The London, or Van der Waals dispersion force is the weakest intermolecular force.

• It is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles.

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Strength of Dispersion Forces • Dispersion forces between molecules are much weaker than the covalent bonds within molecules.

• Molecular size does affect the dispersion forces.

• The bigger the atom, or molecule, there are more electrons, therefore there's a bigger possibility to form temporary dipoles, ann bigger dispersion forces.

• The shapes of the molecules also matter.

• Long thin molecules can form bigger temporary dipoles.

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Hydrogen Bonding • Certain substances such as H2O, HF, NH3 form hydrogen bonds, and the formation of which affects properties (melting point, boiling point, solubility) of the substance.

• Other compounds containing OH and NH2 groups also form hydrogen bonds.

• Molecules of many organic compounds such as alcohols, acids, amines, and aminoacids contain these groups, and thus hydrogen bonding plays an important role in biological science.

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Hydrogen Bonds in DNA

http://tinyurl.com/ygoej6

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VSEPR Theory • The 3D geometry of molecules is determined by the relative orientation of its covalent bonds.

• Ron Gillespie developed a theory to predict the molecular geometry of compounds.

• The Valence‐Shell Electron Pair Repulsion Theory is based on the repulsion of the electrons, and the shape adopted by the molecule is a result of the minimum repulsion of these electron pairs.

• The VSEPR considers 4 types of interactions: single bond, double bond, triple bond , and non‐bonding interactions.

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http://tinyurl.com/n5yvbw

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Resources Used Slide (Group)

Description

Resource

Origin

G1 ‐ 2

Image

Milton

http://bit.ly/XQqEw

G1 ‐ 3

Image

Milton

http://bit.ly/XQqEw

G1 ‐ 4 Animation Idea

Notebook Gallery

G1 ‐ 5

Animation Check this out

Notebook Gallery

G1 ‐ 6

Image

Metallic Bonding

Unknown

G1 ‐ 8

Images

Metallic properties

Unknown

G1 ‐ 11 Animations Intermolecular Forces 1

http://tinyurl.com/l5tt5e

G1 ‐ 12 Image

Water Molecule

http://tinyurl.com/lh8ro6

G1 ‐ 13 Image

Dipole

http://tinyurl.com/mywgww

G1 ‐ 15 Image

Intermolecular Forces 2

http://tinyurl.com/lhwpjl

G1 ‐ 16 Image Hydrogen Bond in Water 1 Animation Hydrogen Bond in Water 2

http://tinyurl.com/m9yvw8 http://tinyurl.com/lh8ro6

G1 ‐ 17 Animation DNA 1 Image DNA 2

http://tinyurl.com/mygfju http://tinyurl.com/ygoej6

G1 ‐ 18 Animation Intermolecular Forces 3

http://tinyurl.com/l2gjdx

G1 ‐ 19 Images

Molecular Geometry 1

Unknown

G1 ‐ 20 Image

Molecular Geometry 2

http://tinyurl.com/n5yvbw

G1 ‐ 19 Animation Ionic vs Covalent Bonding

http://tinyurl.com/lcghho

G1 ‐ 20 Animation Covalent Bonding

http://tinyurl.com/l4psxt

G1 ‐ 21 Animation VSEPR

Unknown

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Teacher's Notes This class has been designed to cover the topics of Metallic Bonding and Intermolecular Forces from Monday, September 7th till Friday, September 11th.

For further knowledge about this topic: 1. Conduct a thorough search under the topic: Metallic Bonding and Intermolecular Forces on the Web, books and magazines.

2. If findings are not specific, ask your teacher for suggestions.

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Objectives • Identify and describe the properties and characteristics of Ionic.

• Identify and describe the interactions and forces between atoms between different compounds.

Note: All, or most, of the objectives will be covered during class time, however the student must be responsible for those objectives not covered or concluded.

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Vocabulary • • • • • •

Metallic Bonding Melting Point Density Intermolecular Forces Van der Waals Dipole

Note: Most of the vocabulary words will be covered during class time, however the student must be responsible for those words not covered or concluded.

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Link and Learn You can visit the following websites to improve your understanding on the present topic: • • • • •

http://tinyurl.com/ndnfp4 http://tinyurl.com/8yb6b http://science‐learning2009.wikispaces.com http://learningandscience.blogspot.com http://libraryatstgeorge.blogspot.com

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Prepared by

Gerardo LAZARO Science Lead Teacher Email: glazaro@sanjorge.edu.pe Wiki: http://science‐learning2009.wikispaces.com Blog: http://learningandscience.blogspot.com Twitter: http://twitter.com/glazaro

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SURVEY If you want to contribute in improving your Chemistry class, click in the survey link:

Term III ‐ 8th A ‐ Class 5

Term III ‐ 8th Alpha ‐ Class 5

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1

What was your UNDERSTANDING of the topic: "Metallic Bonding and Intermolecular Forces"?

A

I understood 25% of the whole topic

B

I understood 50% of the whole topic

C

I understood 75% of the whole topic

D

I understood 100% of the whole topic

E

I didn't understand the class

29

2

What was your level of EFFORT to understand the topic?

A

My effort level was 25%

B

My effort level was 50%

C

My effort level was 75%

D

My effort level was 100%

E

I didn't put any effort

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3

What RESOURCES helped you understand the topic?

A

Text

B

Images

C

Animations

D

Videos

E

Teacher's Speech

F

None

G

Other

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4

How does the SMART Board help you understand the topic?

A

It helps me visualize concepts

B

It helps understand difficult concepts

C

Touching things helps me learn

D

Interacting with the information makes it easier to understand

E

I prefer less effects or audiovisual resources

F

It doesn't really help much

G

I don't like it

32

1

What was your UNDERSTANDING of the topic: "Metallic Bonding and Intermolecular Forces"?

A

I understood 25% of the whole topic

B

I understood 50% of the whole topic

C

I understood 75% of the whole topic

D

I understood 100% of the whole topic

E

I didn't understand the class

33

2

What was your level of EFFORT to understand the topic?

A

My effort level was 25%

B

My effort level was 50%

C

My effort level was 75%

D

My effort level was 100%

E

I didn't put any effort

34

3

What RESOURCES helped you understand the topic?

A

Text

B

Images

C

Animations

D

Videos

E

Teacher's Speech

F

None

G

Other

35

4

How does the SMART Board help you understand the topic?

A

It helps me visualize concepts

B

It helps understand difficult concepts

C

Touching things helps me learn

D

Interacting with the information makes it easier to understand

E

I prefer less effects or audiovisual resources

F

It doesn't really help much

G

I don't like it

36