8th Chemistry - Chemical Bonding

St. George's College

Subject: 8th CHEMISTRY

Teacher's notes

Objectives

Class: Chemical Bonding

Vocabulary Link and Learn

Date: August 24th

2009

In‐Class Survey

Prepared by

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8th Milton A ‐ Chemical Bonding 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 ‐ Chemical Bonding 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...

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ENERGY LEVELS • Electrons move around the nucleus (negative charge around positive charge).

• Even though it looks as if this movement is disorganized, in fact there is a strict organization of the electrons.

• Electrons move around the nucleus packed in Energy Levels.

• Energy levels are the "layers" around the nucleus where electrons are found in motion.

• These energy levels are called Electron shells.

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Rules to fill up the Electron Shells 1. The first electron shell, the closest to the nucleus can hold up to 2 electrons.

2. The other electron shells can hold many more electrons.

3. The last electron shell can only hold up to 8 electrons, this is called the Octet Rule.

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Gilbert Newton Lewis • American physical‐chemist that published "The Atom and the Molecule".

• He is known for the description of the atomic dot diagrams, discovery of the Covalent Bond, description of the Lewis Acid‐ Base definitions, and the discovery of the photon as the minimum unit of radiant energy.

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Dot Diagrams • The electrons located in the last energy level of atoms are called Valence Electrons.

• These electrons are easily recognized when checking the group the atom belongs to in the periodic table.

• The valence electrons are represented by dots or crosses.

• The elements must comply with the Octet Rule., and is used only for single elements or covalent compounds

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Examples

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New knowledge beginning......

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Combining Atoms • All substances are made of atoms of one or more of the 100+ elements.

• Chemical bonding is the joining of atoms to form new substances.

• The properties of these new substances are different from the properties of the original elements.

• An interaction that holds two atoms together is called a chemical bond.

• When chemical bonds form, electrons are shared, gained or lost.

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Electron Number • The number of electrons in an atom can be determined by the atomic number (number of protons). As long as the atom is neutral, with no charge, the atomic number will be the number of electrons.

• The electrons in an atom are organized in energy levels.

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4p 3d

E N E R G Y

4s

3p 3s

2p 2s 1s 13

Valence Electrons • Not all the electrons in an atom make chemical bonds.

• Most atoms form bonds using only the electrons in the outermost energy level.

• An electron in the outermost energy level of an atom is a valence electron.

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Bonding • Not all atoms bond in the same manner. In fact, some rarely bond at all.

• The number of electrons in the outermost energy level of an atom determines whether an atom will form bonds.

• Having 8 valence electrons is a special condition, these atoms do not usually form bonds, because they are stable atoms.

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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 ‐ 6

Images

Electron Shells

http://bit.ly/3Rksdj

G1 ‐ 7

Image

Gilbert Lewis

http://bit.ly/JUcpU

G1 ‐ 8

Animation Example 1

G1 ‐ 9 Images

Dot Diagrams

http://tinyurl.com/l8lsw5 http://tinyurl.com/l8lsw5

G1 ‐ 10 Animation Check this out

Notebook Gallery

G1 ‐ 11 Images

http://tinyurl.com/mkqeo9 http://tinyurl.com/mc33kn

Chemical Bonding 1 Chemical Bonding 2

G1 ‐ 12 Animation NaCl

http://tinyurl.com/l9hjqn

G1 ‐ 14 Image

http://tinyurl.com/mrdvyl

Valence Electrons

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Teacher's Notes This class has been designed to cover the topics of Chemical Bonding from Monday August 24th till Friday August 28th.

For further knowledge about this topic: 1. Conduct a thorough search under the topic: Chemical Bonding 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 Chemical Bonding.

• Review and recognize compounds with different types of bonding, and compare their physical properties.

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 • • • • • • •

Electron: Energy Level: Octet Rule: Ionic bonding: Covalent bonding: Metallic bonding: Crystalline network:

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://www.chemguide.co.uk/atoms/bonding/ionic.html 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 3 Term III ‐ 8th Alpha ‐ Class 3

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Term III ­ Class 2 Chemical Bonding

Grade: Subject: Date:

8th Grade Chemistry ­ A August 24th, 2009

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What was your UNDERSTANDING of the topic: "Chemical Bonding"

1

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

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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

27

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

29

Term III ­ Class 2 Chemical Bonding

Grade: Subject: Date:

8th Grade Chemistry ­ Alpha August 24th, 2009

30

What was your UNDERSTANDING of the topic: "Chemical Bonding"?

1

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

31

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

32

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

34