4.1 predicting chemical reactions

• Explain why the reactivity decreases down group 7 - the difference in the electrons:

  • going down the group, the atoms get bigger
  • outer electrons are further from nucleus
  • attraction between negative electrons and positive nucleus are less strong
• Explain why the reactivity decreases down group 7 - the difference in reactivity:

  • group 7 elements react to become ions with 1- charge. this means they gain 1 electron
  • down the group, there is less attraction for the outer electrons
  • means that the elements gain electrons less easily
• Describe experiment A:

  • Chlorine displaces the bromide ions in NaBr. This leads to the formation of bromine which is orange

  Describe experiment B:

  • There are no observations in experiment B because bromine cannot displace the chlorine ions in NaCl.

  Explain the results:

  • This is because reactivity decreases down group 7. Bromine is lower down than chlorine and therefore is less reactive and cannot displace.