ALH [99] Gases Nobles.ppt

7/29/2019 ALH [99] Gases Nobles.ppt

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Unit 1: The Digestive System

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Unit 15: Genetic EngineeringUnit 16: The Periodic Table and its ElementsUnit 17: The Alkali MetalsUnit 18: Metals and their PropertiesUnit 19: The Transitional Metals

Unit 20: Crude Oil and its ProductsUnit 21: Rock CycleUnit 22: Elements, Molecules and CompoundsUnit 23: Ionic and Covalent CompoundsUnit 24: The Halogens, their Uses and CompoundsUnit 25: The Noble Gases, their Properties and UsesUnit 26: Rates of ReactionUnit 27: Energy

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Unit 25

The Noble Gases, their Properties and Uses

Fluorine Bromine

Iodine

9P+

10N

9E-

Chlorine

17P+

18N

17E-

35P+45N

35E-

53P+74N

53E-

F

Cl

Br

I

9

17

35

53

19

35

80

127

Helium Neon

Krypton

2P+

2N

Argon

18P+

22N

10P+10N

36P+48N

He

Ne

Ar

Kr

2

10

18

36

4

20

40

8436E-

10E-2E-

18E-



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Understand: Keywords:

1. That group VIII elements are called the Noblegases.

2. The physical and chemical properties of group

VIII elements, the Noble gases.3. That they have similar chemical and physicalproperties based on their electronicconfiguration.

4. That because of their full outer shells, theNoble gases do not form compounds with othermetal or non metal elements.

5. Understand that their discovery in theatmosphere was hampered by their stability.

6. Some of the main uses of the Noble gases.

Elements, Noble, Gases, Unreactive,Electrons, Physical, Properties, Inert,Monatomic, Helium, Neon, Argon & Krypton.

Unit 25: The Noble Gases, their Properties and Uses

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Click mouse to begin



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Physical properties of the Noble gases one

He2

Helium

He2

He2

Helium

Ne10

Neon

Ne10

Ne10

Neon

Ar18

Argon

Ar18

Argon

Kr36

Krypton

Kr36

Krypton

Group VIII of the periodic table contains a family of very stable non-metals known as the

Noble gases. This group contains h________, neon, argon and krypton. They are all

monatomic colourless gases. All but helium are found in low quantities in our atmosphere.

Helium is found trapped under the bedrock along with deposits of n_________ gas.Helium is so light that the Earths gravity is not strong enough to keep it in our

atmosphere. Eventually we will run out of helium as it escapes the Earths gravitational

pull. Give two uses helium and neon ?

The Noble gases:


Word bank: helium natural

Position of the Noble gases The Noble gases

Diagram

Notes Found in group VIII of the periodic table,all the Noble gases have eight electrons in

their outermost electron shell. They all

therefore have a full outer shell. This is

what makes them very stable monatomicgases.

The Noble gases have similar chemical and physical

properties because they all have eight electrons in their

outer shell. They are all colourless monatomic gases

which do not form ionic or covalent compounds with

any other elements. They also have extremely lowmelting and boiling points.


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The discovery of the Noble gases

The noble gases were not discovered until about the turn of the last century. Because

the Noble gases are highly un-reactive, they remained hidden in the a____. Helium

was discovered with deposits of natural gas found under the bedrock. In 1892,

scientists discovered that, when all the nitrogen and oxygen from a sample of air wasreacted with hot magnesium, there was around one percent of the gas that would not

react. This small fraction contained n______, argon and krypton.

Discovery of the Noble gases:

100

50

0

Nitrogen Oxygen Noble gases CO2

% composition of noble gases1

0.5

0

Argon Neon Helium Krypton

% composition of noble gases1

0.5

0

Argon Neon Helium Krypton


Word bank: air neon

Percentage composition of noble gases in air Using helium

Diagram

Notes The Noble gases were not discovered until 1892 due to their

stability. They make up only 1% percent of the atmosphere.

Although they are stable they are still useful.

Hydrogen although having

greater lift has now been

replaced by stable helium.

S i I t ti LTD C i ht 2005


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Helium and its uses

Helium is the least dense of the Noble gases. A balloon full of helium will have lift in

normal air. Although hydrogen gives more l_____ because it has the lowest density of

any of the elements it is also highly reactive. Helium makes for a safe alternative and

is used in airships and partyballoonsHelium is also used by deep seas divers insteadof nitrogen. It has a low solubility and therefore reduces the risk of divers suffering

the bends. This is when nitrogen in the blood comes out of solution and begins to

bubble in the b_______. This can be fatal. Why is this condition called the bends !

Helium and its uses:

He2

Helium

He2

He2

Helium


Word bank: lift bubble

Helium Using helium for lift Helium balloons

Diagram

Notes Helium is a low density stable gas that gives

lift to objects like balloons in air. Hydrogen

is better but it is also very unstable and can

react with the oxygen in the atmosphere

forming water. This is an explosive reaction.

Helium is also used for

party balloons. They are

able to rise above the air.

They also (when breathed

in) make you sound like

Mickey Mouse.

S i I t ti LTD C i ht 2005


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Neon and its uses

Neon is the most widely used Noble gas. Neon is used to make fluorescent light tubes,

which can take on many colours. When you pass a high v_______ current across a

tube full of n______, it glows and gives off light. The tubes can be coloured using

various dyes making them ideal for use in advertising signs around the World. If youtake a trip to Londons Piccadilly Circus, then you will see hundreds of flashing neon

signs all advertising various products and fast food companies. Explain why a neon

light uses less energy than a normal filament bulb ?

Neon and its uses:

Ne10

Neon

Ne10

Ne10

Neon

Neon Neon lights at Piccadilly circus Choose a colour

Diagram

Notes Scientists found out that when you pass a

high voltage current through a tube filled

with neon, it fluoresces. Neon lights are used

in advertising signs. There are also more

energy efficient compared to filament bubs.

By colouring the glass

tube you can colour the

light that is emitted. Neon

lights do not produce any

heat and are therefore

much more efficient.


Word bank: voltage neon



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Argon and its uses

Argon makes up nearly one percent of the composition of atmospheric air. Argon is

more dense than air, so balloons filled with just argon appear to sink. Argon has two

main uses. Argon is used to replace air or o________ where you need an oxygen free

environment in order to prevent combustion. Filament b______ made from tungstencontain argon to prevent the tungsten from oxidising with oxygen. Argon is also used

during the welding of metals to prevent metals combusting with oxygen. What other

processes require an oxygen free environment ?

Argon and its uses:

Ar18

Argon

Ar18

Argon


Word bank: oxygen bulbs

Argon Using argon during welding Light bulbs

Diagram

Notes During welding very high temperatures

would cause most metals to begin to react

with oxygen found in air. Argon is flowed

over the weld to prevent the metals reacting.

This techniques is called argonwelding

Light bulbs are filled with

inert argon gas so that the

tungsten filament does not

begin to form tungsten

oxide with oxygen fromthe atmosphere.



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Krypton and its uses

Krypton makes up a very small fraction of the composition of atmospheric air. Like

argon, krypton is more d______ than air. Krypton has one main use. Krypton is used

to produce high energy lasers. These lasers are seen in disco lighting shows. They also

carry sufficient energy to melt metal during their w________. When a high voltagecurrent is applied to the krypton gas, a high energy light is emitted that is used to

produce laser light. Find out from google.co.uk how laser light is produced ?

Krypton and its uses:

Kr36

Krypton

Kr36

Krypton

Krypton Krypton lasers Eye surgery

Diagram

Notes Krypton is used in lasers used for disco

lighting and welding. A high voltage current

is applied to the krypton gas which produces

a high energy beam. This energy is sufficient

to cause melting in metals during welding.

Krypton lasers are use to

remove excess corneal

tissue during laser eye

correction. The cornea is

reshaped to give the

correct focal length.


Word bank: dense melting



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1: Define the following terms: Elements, Reactivity, Noble Gases, Inert, Ionic and Covalent.

2: Look at the three pictures below. Complete the table.

3: Answer the following using the following table:

a) How much (percent) do the noble gases make up of the atmosphere.

b) This gas was used to give lift to air ships.

c) Argon is used in this device to stop the filament from combusting with oxygen.

d) Whereas, the halogens are diatomic gases, the noble gases are what type of gas.

e) All noble gases are said to be chemically what.

Extension questions and homework

Picture Element Properties and uses

One Krypton

Two Neon

Three Helium

Inert Monatomic One percent Diatomic Reactive

Lift Light bulbs Hydrogen Sign Lasers




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4: Complete the following table.

5: Answer the following questions:

a) What would happen when a light bulb is switched on and it is filled with normal air.

b) Airships are no longer filled with, hydrogen. Helium is now used. Explain why.

c) Explain why there are no known compounds that contain either helium, neon, argon or krypton.

d) Why do helium balloons deflate more quickly than balloons filled with atmospheric air.e) How many electrons do (i) group I alkaline metals have in their outer shell (ii) The group VIII noble gases.

f) Explain why the melting and boiling points of the nobles gases increases as you descent the group.

6: Look at the information in the table opposite:

a) Why were the noble gases discovered very late and why do they

have similar properties.

b) Why is neon used in advertising signs.

c) Why will we eventually rum out of the element helium.

d) Why is argon used to replace air in light bulbs.

e) Give two uses of a krypton laser.

Internet:

Go to google.co.uk and find out the Hindenburgdisaster where hydrogen, not helium was used as a lifting gas for

this airship.

Gas Electrons in outer shell State at room temperature Colour Symbol

Helium 2

Neon Gas

Argon colourless

Krypton Kr

Element When found

Gold < 2000 B.C

Helium 1895

Neon 1898

Oxygen 1774

Phosphorus 1669


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ALH [99] Gases Nobles.ppt