GCSE Combined Science (AQA)

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Group 7: Halogens

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Atomic structure and the periodic table The periodic table

Group 7: Halogens

9:51 Group 7 Element Properties, Compounds, and Reactions
Spec 4.1.2.6 4.1.2.1
Previous Group 1: Reaction with Chlorine Next Group 7: Compounds
  • Group seven elements are non-metals known as halogens.
  • Halogens are located on the right side of the periodic table with other non-metals.
  • Halogens consist of molecules made of pairs of atoms.
  • Common halogen molecules include fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2).
  • Halogens are never found as single atoms and exist as pairs when not in compounds.
  • Group seven elements are very reactive.
  • Fluorine is highly reactive and can ignite charcoal when exposed to it.
  • Halogens have seven electrons in their outer shell.
  • All halogens have similar reactions due to their electron configuration.
  • Halogens react with group one alkaline metals like lithium, producing a white salt compound.
  • Halogens gain a single electron to complete their outer shell, forming negative ions.
  • Reactivity of halogens decreases down the group.
  • Fluorine is the most reactive, while iodine is the least reactive.
  • Atoms increase in size down the group, making the outer shell further from the nucleus.
  • There is less attraction between the nucleus and the outer shell as size increases, reducing reactivity.
  • Group seven reactivity trend is opposite to group one, where reactivity increases down the group.
  • Relative molecular mass increases down group seven.
  • Melting and boiling points of halogens increase down the group.
  • Fluorine is a yellow gas at room temperature, while iodine is a dark solid.
  • Intermolecular forces between molecules get stronger down the group, requiring more energy to overcome.
  • Properties can be predicted from trends down a group.
  • Melting and boiling points increase with each element down the group.
  • Estimates for astatine's melting and boiling points can be made based on trends.

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