C4 - Chemical Patterns

C4 Chemical Patterns Revision.

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Group 1: The Alkali Metals

Alkali Metals

  • Float on water - They have low densities
  • Have low melting and boiling points
  • Are shiny when freshly cut
  • Quickly tarnish (rust) in damp air

 Alkali metals react with water to make Hydrogen and an Alkaline solution.
For example:

Sodium + Water  U+2192.svg (http://upload.wikimedia.org/wikipedia/commons/thumb/8/8d/U%2B2192.svg/25px-U%2B2192.svg.png)  Sodium Hydroxide + Hydrogen

 

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Group 1: The Alkali Metals

Going down the group, the reactions get more vigorous.

Metal             Observation

Lithium     -     Lithium floats and fizzes gently

Sodium    -     Sodium melts and whizzes round of surface water
                        Sometimes the hydrogen catches fire    

Potassium  -  Voilent reaction: 
                       Potassium melts and may jump from surface of water
                       Hyrdogen immediately catches fire
         

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Group 1: The Alkali Metals

Alkali metals also react vigorously with chlorine gas to make Chlorides. The Chlorides are colourless crystalline solids. Again, the reactions get more vigorous going down the group.

 

For Example:

 Lithium + Chlorine U+2192.svg (http://upload.wikimedia.org/wikipedia/commons/thumb/8/8d/U%2B2192.svg/25px-U%2B2192.svg.png) Lithium Chloride

 

 

 

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Group 7: The Halogens

As you go down the group, melting points and boiling points increase.

Halogen Molecules are diatomic - They are made from two atoms joined together. For example, the formula for bromine is Br .

 

Halogens are bleaches. They also kill bacteria in water - This helps prevent the spread of disease.

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Group 7: The Halogens

As you go down group 7, the elements become less reactive. For example:

  • Chlorine reacts so fast with hydrogen that it sometime explodes. Bromine reacts quickly but does not explode.
    Iodine reacts more slowly with Hydrogen.

    Chlorine + Hydrogen U+2192.svg (http://upload.wikimedia.org/wikipedia/commons/thumb/8/8d/U%2B2192.svg/25px-U%2B2192.svg.png) Hydrogen Chloride

  • Hot iron glows brightly in chlorine gas. It glows less Brightly in Bromine, and Hardly at all in iodine.

    Iron + Chlorine U+2192.svg (http://upload.wikimedia.org/wikipedia/commons/thumb/8/8d/U%2B2192.svg/25px-U%2B2192.svg.png) Iron Chloride

 

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Explaining patterns in the properties of elements

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Comments

Emma

This was a really useful Resource, Thanks :D

raf

ty nice info

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