Chemical Properties of Group 17 Elements

Chemical Properties of Halogens

  1. Group 17 elements are very reactive non-metals.
  2. The atoms all have 7 valence electrons, makes them have very similar chemical properties.
  3. During a chemical reaction, the atom gains one electron to form an ion with a charge of -1.

  1. The reactivity of group 1 decreases down the group.
  2. All group 17 elements are poisonous.
  3. Astatine is very radioactive.

Safety Precaution

  1. Fluorine, chlorine and bromine gases are poisonous.
  2. Therefore all the experiments involving these gases should be carried out in a fume chamber.
  3. The experiments involve fluorine are nor done in school.
  4. This is because fluorine is so reactive that it will react with most of the substance it comes into contact with.
  5. It is very difficult to conduct experiments involving fluorine.

Explaining the Reactivity Trend of the Halogens

  1. The reactiveness of halogens decreases down the group.
  2. This can be explained as below:
    1. When a halogen atom reacts, it gains an electron to form a singly negative charged ion.
    2. As we go down the group from F → Cl → Br → I, the size of the atom increases due to an extra filled electron shell.
    3. The valence electrons are further and further from the nucleus, the attraction force between the electrons and the nucleus become weaker and weaker.
    4. Therefore the ability of the atom to attract an electron to fill the outermost shell reduces., which means the reactiveness of the atom reduces.