1. 2.1.2 Noble Gases

2. 2.1 Chemical Compounds [5 class periods]
1. Relate the stability of Noble Gases to having a full outer shell of electrons
1. Know uses of helium and argon related to their chemical unreactivity.
1. Understand bonding and valency in terms of the attainment of a stable electronic structure.
2. Know the Octet rule and its limitations
3. Predict simple chemical formulae of the first 36 elements (excluding d-block elements)
3. Predict the formulae of hydroxides, carbonates, nitrates, hydrogencarbonates, sulfites and sulfates of these elements (where such exist).
3. Realise that transition elements (Cu, Fe, Cr and Mn only) show Variable Valency

3. Discovered He 1868 Ar 1894 Ne, Kr and Xe in 1898 Rn 1900
Unreactive because they have a full outer shell of electrons

4. Uses Helium used in airships as it is lighter than air
Not as light as hydrogen [twice as heavy per volume] but does not burn [Hindenberg]
Used in making the atmosphere of deep sea divers as it is less likely to cause the “bends” –
It gives the diver a “Mickey Mouse” voice because it has such a low density compared to air.

5. Argon The most common Noble Gas.
Used to fill normal incandescent light bulbs to stop them imploding, to reduce evaporation of the filament and because it is unreactive
Used as inert atmosphere for welding

6. All atoms are trying to get structure of nearest Noble Gas
i.e. eight electrons in their outer shell and thus stability

7. Trends in Noble gases
Noble gases don’t react in general because they have a full outer shell.
As one goes down the Group the molecules are larger
Makes it easier to form temporary dipoles due to larger electron clouds
So van der Waal’s forces are greater
More energy required to break these.
So MP and BP get higher
Same trend in halogens