Predicting Reactivity (OCR GCSE Combined Science A (Gateway))

Revision Note

Predicting Reactivity

  • Using some of the patterns of reactivity in the Periodic Table we can predict what properties an element may have 

  • Key patterns include:

    • Elements in Group 1 and 2 are highly reactive 

    • Metals in Group 1 and 2 get more reactive as you go down

    • Metals form ionic compounds with reactive non metals

    • Non- metals in Group 7 get less reactive as you go down 

    • Group 0 elements are unreactive

4-1-4-the-periodic-table-trends-in-reactivity-

Comparison of Transition Metals and Group 1 Properties

  • There are also some key differences between the reactivity of transition metals and Group 1 metals

  • All of the group 1 metals form ions with a +1 charge while the transition metals can form ions with variable charges

    • For example iron can form an Fe2+ ion or an Fe3+ ion

  • The transition metals are much harder, stronger and denser than the group 1 metals, which are very soft and light

  • They have much higher melting points e.g. titanium melts at 1,688 ºC whereas potassium melts at only 63.5 ºC, not far off the average cup of tea!

  • The transition metals are much less reactive than the group 1 metals

  • The alkali metals react with water, oxygen and halogens while the transition metals either react very slowly or do not react at all

  • A classic example of this is the reaction with oxygen

  • A Group 1 metal will tarnish in the presence of oxygen as a metal oxide is formed

  • When cut with a knife, the shiny appearance of the metal disappears in seconds as it is covered by the dull metal oxide

  • Iron on the other hand can take several weeks to react with oxygen to form iron oxide (rust) and requires the presence of water

Examiner Tips and Tricks

Sometimes you are asked to identify unknown elements from the Periodic Table based on these properties so make sure you remember them!

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