Absorb Chemistry for GCSE by Lawrie Ryan
     
Group 0 – The Noble Gases
Introduction


Imagine a group in the Periodic Table that has hardly any chemical reactions to remember. 'Great!' you might say. Well here it is – the last group in the Periodic Table, Group 0 (sometimes referred to as Group 8) – the noble gases.

Properties of the noble gases
The elements in
Group
Groups are the vertical columns in the Periodic Table, consisting of elements with similar properties (chemical 'families').
Group
0 of the
Periodic Table
The Periodic Table is a table listing the elements in order of atomic number, arranged so that similar elements appear in columns.
Periodic Table
are:



These are all colourless
monatomic
A monatomic gas is one that exists as single atoms.
monatomic
gases. Monatomic means that the gases exist as single, unbonded atoms.

We see some trends in the physical properties of the
noble gases
The noble gases are the elements in Group 0 (sometimes called Group 8) in the Periodic Table: helium, neon, argon, krypton, xenon, and radon.
noble gases
going down the group. Look at the graphs below:

Figure 1.  Boiling points of the noble gases.
Figure 2.  Density of the noble gases.
Decide whether the following statements below are true or false.
  The boiling points of the noble gases increase as we go down the group.
  The boiling points of the noble gases decrease as we go down the group.
  The density of the noble gases decreases as we go down the group.
  The density of the noble gases increases as we go down the group.
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Which gas has the strongest forces between its atoms?
 
Neon
Xenon
Radon
Helium
Argon
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Why are the noble gases so unreactive?
The noble gases were originally called the
inert
'Inert' means unreactive.
inert
gases. The word 'inert' describes a substance that has no reactions. However, in 1962 the first
compound
A compound is a substance made up of more than one type of atom.
compound
containing a noble gas was made and the group was later renamed!

Look at the atoms of the first three noble gases below:

Figure 3.  The electronic structures of the noble gases.
What do you notice about the highest energy level (outermost) shell of each noble gas?
 
The outer shell contains 2 electrons.
The outer shell is full of electrons.
The outer shell contains 8 electrons.
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It is the complete highest energy level (full outer shell) that makes the atoms of a noble gas so stable and unlikely to react. There are only a few compounds of noble gases, mainly formed with the reactive elements fluorine and oxygen, and then only with the larger noble gases.

Which of these
halogens
The halogens are the elements of Group 7 in the Periodic Table: fluorine, chlorine, bromine, iodine, and astatine.
halogens
do you think was first found to react with a noble gas?
 
Iodine
Fluorine
Bromine
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Uses of the noble gases
Here are some of the main uses of the noble gases:

Helium is used:

Figure 4.  


Neon is used:

Figure 5.  Neon lights glowing red.


Argon is used:


Krypton is used:

Figure 6.  Krypton used in lasers for eye surgery.


Radon is used:

Why is helium used in balloons?
 
Because of its low boiling point
Because of its low density
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Why is argon used inside light bulbs?
 
Because it glows brightly
Because, unlike oxygen, it does not react with the the hot tungsten filament
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Summary


The noble gases in Group 0 (or 8) of the Periodic Table are very unreactive gases.

This is because their atoms have complete highest energy levels (full outer shells) of electrons.

Their melting points and density rise as we go down the group.

Exercises
1. The noble gases are 'monatomic' gases. What does this mean?
 
 
2. All other conditions being equal, which of these noble gases has the highest density?
 
Helium
Neon
Argon
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3. Which of these noble gases has the highest boiling point?
 
Helium
Neon
Argon
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4. Why are the noble gases so unreactive?
 
 
5. Match the noble gas to one of its uses:
  Helium
  Neon
  Argon
  Krypton
  Radon
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