Year 8 - Unit 2 - Presentation - Lesson 11 (3).pptx

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• Chemistry
• Lower Secondary (Key Stage 3)

The Periodic Table

Lesson 11 - Group 7

Science

Chemistry - Key Stage 3

Miss Willett

Today we will be looking at:

Know where Group 7 elements are on the periodic table

Describing properties of Group 7 elements

Describing trends in properties of Group 7 elements

Writing equations to represent some reactions of Group 7

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What do you find in the nucleus of an atom?

A

Protons

B

Photon

C

Neutrons

D

Electrons

What does the word ‘ductile’ mean?

A

Able to be drawn into wires

B

Inflexible

C

Brittle

What charge do compounds have, overall?

A

Neutral

B

Positive

C

Negative

What color do group 7 elements turn as you go down the periodic table?

A

They become more metallic.

B

They become lighter in color.

C

They become transparent.

D

They become darker in color.

What color is a typical halogen at room temperature?

A

Red

B

Blue

C

Purple

D

Yellow-green

What color does chlorine gas appear?

A

Blue

B

Pale green

C

Red

D

Yellow

What color is bromine at room temperature?

A

Blue

B

Green

C

Yellow

D

Red-brown

What is the color of iodine as a solid?

A

Black

B

Yellow

C

Violet

D

Brown

Physical properties of Group 7

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Group 7 properties

• Group 7 = the halogens

• They have 7 electrons on their outer shell

• Non-metals, coloured, poisonous

Source: Oak

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Water

0

-10

-20

70

60

50

40

30

20

10

80

90

100

-30

Melting point

110

120

130

Boiling point

Solid

Liquid

Gas

(Temp °C)

Melting point (solid → liquid) = 0°C

Boiling point (liquid → gas) = 100°C

How do the melting points and boiling points link to state of matter?

Credit: Miss Willett

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Group 7 properties

How do the melting points and boiling points link to state of matter?

Credit: Miss Willett

The melting points and boiling points of the halogens increase going down group 7. This is because, going down group 7:

• the molecules become larger

• the intermolecular forces become stronger

• more energy is needed to overcome these forces

Why do the melting and boiling points of the halogens increase going down group 7?

A

more energy is needed to overcome these forces

B

the molecules become larger

C

the intermolecular forces become stronger

What factor causes the increase in melting and boiling points of the halogens going down group 7?

A

the molecules become smaller

B

less energy is needed to overcome these forces

C

the intermolecular forces become stronger

How many elements in the halogens are gases at room temperature?

A

4

B

2

C

1

D

3

How many elements in the halogens are solids at room temperature?

A

4

B

1

C

2

D

3

How many elements in the halogens are liquids at room temperature?

A

1

B

3

C

2

D

4

What is the color difference between fluorine and chlorine?

A

Fluorine is pale yellow, Chlorine is green.

B

Fluorine is green, Chlorine is pale yellow.

In which state of matter is bromine?

A

Bromine is a liquid at room temperature.

B

Bromine is a gas at room temperature.

Which halogen is solid at room temperature?

A

Iodine is solid at room temperature.

B

Chlorine is solid at room temperature.

Trends in Group 7

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Go to the worksheet to watch the video!

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True or false?

The halogens were reacted with argon

TRUE

FALSE

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True or false?

When they reacted, an ‘-ate’ was formed

TRUE

FALSE

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True or false?

Fluorine was the most reactive halogen

TRUE

FALSE

1.Which metal are the halogens being reacted with?

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What observations did you make?

Pause the video to complete your task

Can you describe the reactivity as you move down the group?

2.Name the product formed in each reaction

3.Which of the halogens reacted is most reactive?

4.Which of the halogens reacted is least reactive?

For example, fluorine + ________ → _________ fluoride

1.Which metal are the halogens being reacted with?

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What observations did you make?

2.Name the product formed in each reaction

How did you do?!

Fluorine + iron → iron fluoride

Chlorine + iron → iron chloride

Bromine + iron → iron bromide

Iodine + iron → iron iodide

Iron

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What observations did you make?

As you go down group 7, the elements get less reactive

3.Which of the halogens reacted is most reactive?

4.Which of the halogens reacted is least reactive?

How did you do?!

Fluorine

Iodine

Group 7 and Group 1

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Reactions with Group 7 + Group 1?

Lithium + chlorine → lithium chloride

• Metal name jumps

• Non-metal forms surname

• 2 elements = -ide

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Sodium + chlorine → sodium chloride

Potassium + fluorine → potassium fluoride

What’s missing?!

Lithium + iodine → lithium iodide

Potassium + bromine → potassium bromide

Complete the following word equations:

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Reactions of group 7 + group 1

• Lithium + fluorine → ________ ________

• Sodium + chlorine → ________ ________

• Potassium + __________ → __________ iodide

• ____________ + bromine → caesium __________

• __________ + ___________ → sodium fluoride

Pause the video to complete your task

Complete the following word equations:

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Reactions of group 7 + group 1

• Lithium + fluorine → lithium fluoride

• Sodium + chlorine → sodium chloride

• Potassium + iodine → potassium iodide

• Caesium + bromine → caesium bromide

• Sodium + fluorine → sodium fluoride

How did you do?!

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Why do group 1 + 7 react so well?

• Loses one electron

• +1 charge

• Gains one electron

• -1 charge

Source: Oak

Source: Oak

Credit: Miss Willett

Credit: Miss Willett

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Group 1 + 7 charges and equations:

• Lithium makes a +1 ion as it loses 1 electron

• Fluorine makes a -1 ion as it gains 1 electron

• So we need one of each for a neutral compound

+ F

--> LiF

Li

Credit: Miss Willett

Credit: Miss Willett

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What’s the charge?

What’s the compound?

Potassium?

Bromine?

Potassium bromide?

K: +1

Br: -1

KBr

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What’s the charge?

What’s the compound?

Sodium?

Chlorine?

Sodium chloride?

Na: +1

Cl: -1

NaCl

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What’s the charge?

What’s the compound?

Lithium?

Iodine?

Lithium iodide?

Li: +1

I: -1

LiI

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What’s the charge?

What’s the compound?

Sodium?

Bromine?

Sodium bromide?

Na: +1

Br: -1

NaBr

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Bringing it all together..

Consolidate your learning from today

Pause the video to complete the task

1. Describe the appearance of chlorine at room temperature.

2. Describe the trend in reactivity down group 7.

3. Why do group 7 elements form -1 charges when they bond?

4. Create the word equation for the reaction of caesium and iodine.

5. Devise the formula for the compound formed.

What is the appearance of chlorine at room temperature?

A

Brown solid

B

Colorless liquid

C

Greenish-yellow gas

D

Reddish-orange vapor

What is the trend in reactivity down group 7?

A

Reactivity remains constant

B

Reactivity increases

C

Reactivity is unpredictable

D

Reactivity decreases

Why do group 7 elements form -1 charges when they bond?

A

They do not participate in bonding

B

They lose an electron to achieve a full outer shell

C

They share electrons with other elements

D

They gain an electron to achieve a full outer shell

Create the word equation for the reaction of caesium and iodine.

A

Caesium + Iodine -> Caesium Iodide

B

Caesium + Iodine -> Caesium Diiodide

C

Caesium + Iodine -> Caesium Triiodide

D

Caesium + Iodine -> Caesium Iodine

Devise the formula for the compound formed in the reaction of caesium and iodine.

A

CsI2

B

CsI

C

Cs2I

D

Cs3I

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Bringing it all together..

Consolidate your learning from today

1. Chlorine is a pale green gas at room temperature

2. Reactivity decreases down group 7

3. Group 7 elements form -1 charge because they gain one electron

4. Caesium + iodine → caesium iodide

How did you do?!

Cs (+1) + I (-1) → CsI

Where will be going next?

Knowing what a displacement reaction is

Predicting products of displacement

Using equations to represent displacement

Understand why reactivity changes in Group 7

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