Group 1: Reactivity & Electronic Configurations (Edexcel IGCSE Chemistry (Modular))

Revision Note

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Electronic configuration of Group 1 elements

  • The reactivity of the Group 1 metals increases as you go down the group

  • When a Group 1 element reacts its atoms only need to lose electron, as there is only 1 electron in the outer shell

    • When this happens, 1+ ions are formed

  • The next shell down automatically becomes the outermost shell and since it is already full, a Group 1 ion obtains noble gas configuration

  • As you go down Group 1, the number of shells of electrons increases by 1

    • This means that the outermost electron gets further away from the nucleus, so there are weaker forces of attraction between the outermost electron and the nucleus

    • Less energy is required to overcome the force of attraction as it gets weaker, so the outer electron is lost more easily

    • So, the alkali metals get more reactive as you descend the group

Electronic configuration of Group 1 elements

Electronic configuration of Li, Na and K, IGCSE & GCSE Chemistry revision notes

These electron shell diagrams of the first 3 alkali metals show that the Group 1 metals have 1 electron in their outer shell

Examiner Tip

In your exams, you could be asked to explain the trend in reactivity of the alkali metals - make sure you answer this question using their electronic configuration to support your answer.

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